This topic describes how to list all objects in a bucket, a specific number of objects, and objects whose names contain a specific prefix in an Object Storage Service (OSS) bucket.
Limit
In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.
In this topic, access credentials are obtained from environment variables. For more information about how to configure access credentials, see Configure access credentials.
In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Configuration examples for common scenarios.
To list objects, you must have the
oss:ListObjectspermission. For more information, see Grant custom permissions to a RAM user.
Background information
You can call the GetBucket (ListObjects) or GetBucketV2 (ListObjectsV2) operation to list up to 1,000 objects in a bucket at a time. You can specify list operation parameters to list objects based on your business requirements. For example, you can list all the objects after a specific position, list all objects and subdirectories in a specific directory, and list more than 1,000 objects by page. The GetBucket (ListObjects) and GetBucketV2 (ListObjectsV2) operations have some differences:
When you call the GetBucket (ListObjects) operation to list objects, the object owner information is included in the response.
When you call the GetBucketV2 (ListObjectsV2) operation to list objects, you can configure the fetchOwner parameter to specify whether to include the object owner information in the response.
NoteTo list objects in a versioning-enabled bucket, we recommend that you call the GetBucketV2 (ListObjectsV2) operation.
The following tables describe the parameters that you can configure when you call the GetBucket (ListObjects) or GetBucketV2 (ListObjectsV2) operation to list objects.
Call the GetBucket (ListObjects) operation to list objects
You can call GetBucket (ListObjects) in one of the following formats:
ObjectListing listObjects(String bucketName): lists all objects in a bucket. By default, up to 100 objects can be listed in a single request.
ObjectListing listObjects(String bucketName, String prefix): lists objects whose names contain a specific prefix in a bucket. By default, up to 100 objects can be listed in a single request.
ObjectListing listObjects(ListObjectsRequest listObjectsRequest): lists objects that meet specified conditions. You can use this format to list objects in a flexible manner.
The following table describes the parameters associated with the GetBucket (ListObjects) operation.
Parameter
Description
Method
objectSummaries
The metadata of the objects that you want to list.
List<OSSObjectSummary> getObjectSummaries()
prefix
The prefix that must be included in the names of objects to list.
String getPrefix()
delimiter
The character that is used to group objects by name.
String getDelimiter()
marker
The position from which the list operation starts.
String getMarker()
maxKeys
The maximum number of objects that can be listed each time.
int getMaxKeys()
nextMarker
The position from which the next list operation starts.
String getNextMarker()
isTruncated
Specifies whether the object listing is truncated. Valid values:
false: All objects are listed without truncation.
true: Only part of the objects are listed.
boolean isTruncated()
commonPrefixes
A set of substrings of object names. Objects whose names end with the delimiter and contain the same prefix are grouped as a single result element in commonPrefixes.
List<String> getCommonPrefixes()
encodingType
The encoding type of the content in the response.
String getEncodingType()
Call the GetBucketV2 (ListObjectsV2) operation to list objects
You can call the GetBucketV2 (ListObjectsV2) operation in one of the following formats:
ListObjectsV2Result listObjectsV2(String bucketName): lists all objects in a bucket. By default, up to 100 objects can be listed in a single request.
ListObjectsV2Result listObjectsV2(String bucketName, String prefix): lists objects whose names contain a specific prefix in a bucket. By default, up to 100 objects can be listed in a single request.
ListObjectsV2Result listObjectsV2(ListObjectsRequest listObjectsRequest): lists objects for which multiple conditions are specified. You can use this format to list objects in a flexible manner.
The following table describes the parameters that you can configure for the GetBucketV2 (ListObjectsV2) operation.
Parameter
Description
Method
objectSummaries
The metadata of the objects that you want to list.
List<OSSObjectSummary> getObjectSummaries()
prefix
The prefix that must be included in the names of objects that you want to list.
String getPrefix()
delimiter
The character used to group the objects that you want to list by name.
String getDelimiter()
startAfter
The position from which the list operation starts.
String getStartAfter()
maxKeys
The maximum number of objects that can be listed each time.
int getMaxKeys()
continuationToken
The position from which the list operation starts.
String getContinuationToken()
nextContinuationToken
The position from which the next list operation starts.
String getNextContinuationToken()
isTruncated
Specifies whether the listed objects are truncated. Valid values:
false: All objects are listed without truncation.
true: Only a part of the objects are listed.
boolean isTruncated()
commonPrefixes
A set of substrings of object names. Objects whose names end with the delimiter and contain the same prefix are grouped as a single result element in CommonPrefixes.
List<String> getCommonPrefixes()
encodingType
The encoding type of the object names in the response.
String getEncodingType()
fetchOwner
Specifies whether to include the owner information in the response. Valid values:
true: The response includes the owner information.
false: The response does not include the owner information.
String getFetchOwner()
Simple list
You can call the GetBucket (ListObjects) operation or the GetBucketV2 (ListObjectsV2) operation to list objects in a specific bucket.
Call the GetBucket (ListObjects) operation
The following code provides an example on how to call the GetBucket (ListObjects) operation to list objects in a specific bucket. By default, 100 objects are listed by a request.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix in the names of the objects that you want to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects. If you do not set keyPrefix, all objects in the bucket are listed. If you set keyPrefix, the objects whose names contain the specified prefix are listed.
ObjectListing objectListing = ossClient.listObjects(bucketName, keyPrefix);
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
} Call the GetBucketV2 (ListObjectsV2) operation
The following code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list objects in a specific bucket. By default, 100 objects are listed by a request.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix in the names of the objects that you want to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects. If you do not set keyPrefix, all objects in the bucket are listed. If you set keyPrefix, the objects whose names contain the specified prefix are listed.
ListObjectsV2Result result = ossClient.listObjectsV2(bucketName, keyPrefix);
List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();
for (OSSObjectSummary s : ossObjectSummaries) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}Call ListObjectsRequest to list objects
You can configure parameters of ListObjectsRequest to list objects in a flexible manner. The following table describes the parameters that you can configure.
Parameter | Description | Method |
prefix | The prefix that the names of returned objects must contain. | setPrefix(String prefix) |
delimiter | The character that is used to group the objects that you want to list by name. For example, you can set the delimiter to a forward slash (/). Objects whose names contain the same string that stretches from the specified prefix to the first occurrence of the forward slash (/) are grouped as a CommonPrefixes element. All objects whose names contain the CommonPrefixes elements are listed. You can use the delimiter parameter to manage and query objects in a hierarchical manner. This ensures more organized and intuitive query results. | setDelimiter(String delimiter) |
marker | List objects whose names are alphabetically after the object specified by marker. Objects whose names are alphabetically after the value of marker are listed. | setMarker(String marker) |
maxKeys | The maximum number of objects that can be listed at a time. After you specify this parameter, objects are returned in alphabetical order. The default value is 100. The maximum value is 1000. | setMaxKeys(Integer maxKeys) |
encodingType | The encoding type of the object names in the response. Only URL encoding is supported. | setEncodingType(String encodingType) |
List a specific number of objects
The following code provides an example on how to list a specific number of objects.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// Specify the maximum number of objects that can be listed each time.
final int maxKeys = 200;
// List objects.
ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMaxKeys(maxKeys));
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
} List objects whose names contain a specified prefix
The following code provides an example on how to list objects whose names contain a specific prefix in a bucket.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix in the names of the objects that you want to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects whose names contain a specific prefix. By default, 100 objects are listed.
ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withPrefix(keyPrefix));
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
} List the objects whose names are alphabetically after the object specified by marker
The following sample code provides an example on how to list objects whose names are alphabetically after the value of marker.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the name of the object after which the list begins. If this parameter is specified, objects whose names are alphabetically after the value of marker are returned.
String marker = "ex";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects after the object specified by Marker. By default, 100 objects are listed.
ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMarker(marker));
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List all objects in a bucket by page
The following sample code provides an example on how to list all objects in a specific bucket by page. You can set maxKeys to specify the maximum number of objects that can be listed on each page.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Set maxKeys to 200.
int maxKeys = 200;
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
String nextMarker = null;
ObjectListing objectListing;
do {
objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMarker(nextMarker).withMaxKeys(maxKeys));
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
nextMarker = objectListing.getNextMarker();
} while (objectListing.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects whose names contain a specific prefix by page
The following code provides an example on how to list objects whose names contain a specified prefix by page.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify that up to 200 objects can be listed on each page.
int maxKeys = 200;
// Specify the prefix in the names of the objects that you want to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the marker parameter. Example: objecttest.txt.
String nextMarker = "objecttest.txt";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
ObjectListing objectListing;
do {
objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).
withPrefix(keyPrefix).withMarker(nextMarker).withMaxKeys(maxKeys));
List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
nextMarker = objectListing.getNextMarker();
} while (objectListing.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects whose names are encoded by the specified encoding type
If the name of an object contains one of the following special characters, the object name must be URL-encoded before the object can be transmitted. OSS supports only URL encoding.
Single quotation marks (' ')
Double quotation marks (" ")
Ampersands (&)
Angle brackets (< >)
Pause markers (、)
Chinese characters
The following code provides an example on how to list objects whose names are encoded by a specific encoding type.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.net.URLDecoder;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify that up to 200 objects can be listed on each page.
int maxKeys = 200;
// Specify the prefix in the names of the objects that you want to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the marker parameter. Example: objecttest.txt.
String nextMarker = "objecttest.txt";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
ObjectListing objectListing;
do {
ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName);
listObjectsRequest.setPrefix(keyPrefix);
listObjectsRequest.setMaxKeys(maxKeys);
listObjectsRequest.setMarker(nextMarker);
// Specify the encoding type of the object names.
listObjectsRequest.setEncodingType("url");
objectListing = ossClient.listObjects(listObjectsRequest);
// Decode the value of Key in the response.
for (OSSObjectSummary objectSummary: objectListing.getObjectSummaries()) {
System.out.println("Key:" + URLDecoder.decode(objectSummary.getKey(), "UTF-8"));
}
// Decode the value of commonPrefixes in the response.
for (String commonPrefixes: objectListing.getCommonPrefixes()) {
System.out.println("CommonPrefixes:" + URLDecoder.decode(commonPrefixes, "UTF-8"));
}
// Decode the value of nextMarker in the response.
if (objectListing.getNextMarker() != null) {
nextMarker = URLDecoder.decode(objectListing.getNextMarker(), "UTF-8");
}
} while (objectListing.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}Call the ListObjectsV2Request operation to list objects
You can specify parameters when you call the ListObjectsV2Request operation to list objects in a flexible manner. For example, you can list a specified number of objects, objects whose names contain a specific prefix, or all objects in a bucket by page.
The following table describes the parameters that you can configure.
Parameter | Description | Method |
prefix | The prefix that the names of returned objects must contain. | setPrefix(String prefix) |
delimiter | The character that is used to group the objects that you want to list by name. For example, you can set the delimiter to a forward slash (/). Objects whose names contain the same string that stretches from the specified prefix to the first occurrence of the forward slash (/) are grouped as a CommonPrefixes element. All objects whose names contain the CommonPrefixes elements are listed. You can use the delimiter parameter to manage and query objects in a hierarchical manner. This ensures more organized and easy-to-understand query results. | setDelimiter(String delimiter) |
maxKeys | The maximum number of objects that can be listed at a time. After you specify this parameter, objects are returned in alphabetical order. The default value is 100. The maximum value is 1000. | setMaxKeys(Integer maxKeys) |
startAfter | The position from which the list operation starts. Objects whose names are alphabetically after the value of startAfter are listed. | setStartAfter(String startAfter) |
continuationToken | The token used in this list operation. | setContinuationToken(String continuationToken) |
encodingType | The encoding type of the object names in the response. Only URL encoding is supported. | setEncodingType(String encodingType) |
fetchOwner | Specifies whether to include the object owner information in the response. | setFetchOwner(boolean fetchOwner ) |
List a specified number of objects
The following code provides an example on how to list a specified number of objects.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the maximum number of objects that can be listed each time.
int maxKeys = 200;
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects, each time request default returns 100 objects, this time specify settings maximum return file number is 200.
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
listObjectsV2Request.setMaxKeys(maxKeys);
ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();
for (OSSObjectSummary s : ossObjectSummaries) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects whose names contain a specified prefix
The following code provides an example on how to list objects whose names contain a specified prefix.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix that must be included in the names of objects to list. Example: exampledir/object.
String prefix = "exampledir/object";
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// List objects whose names contain a specific prefix.
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
listObjectsV2Request.setPrefix(prefix);
ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();
for (OSSObjectSummary s : ossObjectSummaries) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects whose names are alphabetically after the object specified by startAfter
The following code provides an example on how to list objects whose names are alphabetically after the object specified by startAfter.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// Specify the name of the object after which the list begins.
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
listObjectsV2Request.setStartAfter("ex");
ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();
for (OSSObjectSummary s : ossObjectSummaries) {
System.out.println("\t" + s.getKey());
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects and their owner information
The following code is used to list the owner information of files in the results.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// By default, the owner information of the objects is not listed. To include the object owner information in the response, set the fetchOwner parameter to true.
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
listObjectsV2Request.setFetchOwner(true);
ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();
for (OSSObjectSummary s : ossObjectSummaries) {
System.out.println("\t" + s.getKey());
if (s.getOwner() != null) {
System.out.println("owner id:" + s.getOwner().getId());
System.out.println("name:" + s.getOwner().getDisplayName());
}
}
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List all objects by page
The following code provides an example on how to list all objects in a specified bucket by page. You can set maxKeys to specify the maximum number of objects that can be listed on each page.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the maximum number of objects that can be listed at a time.
int maxKeys = 200;
// Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
String nextContinuationToken = null;
ListObjectsV2Result result = null;
// List objects by page by using the nextContinuationToken parameter included in the response of the previous list operation.
do {
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
listObjectsV2Request.setContinuationToken(nextContinuationToken);
result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> sums = result.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
nextContinuationToken = result.getNextContinuationToken();
} while (result.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}List objects whose names contain a specified prefix by page
The following code provides an example on how to list objects whose names contain a specified prefix by page:
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.util.List;
public class Demo {
public static void main(String[] args) throws Exception {
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix that must be included in the names of objects to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the maximum number of objects that can be listed at a time.
int maxKeys = 200;
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
String nextContinuationToken = null;
ListObjectsV2Result result = null;
// List the objects whose names contain the specified prefix by page.
do {
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
listObjectsV2Request.setPrefix(keyPrefix);
listObjectsV2Request.setContinuationToken(nextContinuationToken);
result = ossClient.listObjectsV2(listObjectsV2Request);
List<OSSObjectSummary> sums = result.getObjectSummaries();
for (OSSObjectSummary s : sums) {
System.out.println("\t" + s.getKey());
}
nextContinuationToken = result.getNextContinuationToken();
} while (result.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}Specify file name encoding
The following code provides an example on how to list objects and specify the encoding type of the object names in the response:
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.net.URLDecoder;
public class Demo {
public static void main(String[] args) throws Exception {
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you execute the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the bucket name. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the prefix that must be included in the names of objects to list. Example: exampledir/object.
String keyPrefix = "exampledir/object";
// Specify the maximum number of objects that can be listed at a time.
int maxKeys = 200;
// Specify the region of the bucket that you want to access. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
String region = "cn-hangzhou";
// Create an OSSClient instance.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
String nextContinuationToken = null;
ListObjectsV2Result result = null;
// Specify that the returned results are URL-encoded. In this case, you must decode the values of the prefix, delimiter, startAfter, key, and commonPrefix parameters in the response.
do {
ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
listObjectsV2Request.setPrefix(keyPrefix);
listObjectsV2Request.setEncodingType("url");
listObjectsV2Request.setContinuationToken(nextContinuationToken);
result = ossClient.listObjectsV2(listObjectsV2Request);
// Decode the value of prefix in the response.
if (result.getPrefix() != null) {
String prefix = URLDecoder.decode(result.getPrefix(), "UTF-8");
System.out.println("prefix: " + prefix);
}
// Decode the value of delimiter in the response.
if (result.getDelimiter() != null) {
String delimiter = URLDecoder.decode(result.getDelimiter(), "UTF-8");
System.out.println("delimiter: " + delimiter);
}
// Decode the value of startAfter in the response.
if (result.getStartAfter() != null) {
String startAfter = URLDecoder.decode(result.getStartAfter(), "UTF-8");
System.out.println("startAfter: " + startAfter);
}
// Decode the value of key in the response.
for (OSSObjectSummary s : result.getObjectSummaries()) {
String decodedKey = URLDecoder.decode(s.getKey(), "UTF-8");
System.out.println("key: " + decodedKey);
}
// Decode the value of commonPrefixes in the response.
for (String commonPrefix: result.getCommonPrefixes()) {
String decodeCommonPrefix = URLDecoder.decode(commonPrefix, "UTF-8");
System.out.println("CommonPrefix:" + decodeCommonPrefix);
}
nextContinuationToken = result.getNextContinuationToken();
} while (result.isTruncated());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}Directory feature
OSS uses a flat structure for objects instead of a hierarchical structure to store objects. A directory is an object whose size is 0 and whose name ends with a forward slash (/). You can upload and download this object. By default, objects whose names end with a forward slash (/) are displayed as directories in the OSS console. For the complete sample code for creating a directory, see GitHub.
You can specify the delimiter and prefix parameters to list objects by directory:
If you set prefix to a directory name in the request, objects and subdirectories whose names contain the prefix are listed.
If you also set delimiter to a forward slash (/) in the request, the objects and subdirectories whose names start with the specified prefix in the directory are listed. Each subdirectory is listed as a single result element in CommonPrefixes. The objects and directories in these subdirectories are not listed.
Assume that a bucket contains the following objects: oss.jpg, fun/test.jpg, fun/movie/001.avi, and fun/movie/007.avi, with the forward slash (/) as the directory delimiter. The following examples describe how to list objects in simulated directories.
List all objects in a bucket
Call the GetBucket (ListObjects) operation to list all objects in a bucket
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // Create a ListObjectsRequest. ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName); // List objects. ObjectListing listing = ossClient.listObjects(listObjectsRequest); // Traverse all objects. System.out.println("Objects:"); for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all CommonPrefix elements. System.out.println("CommonPrefixes:"); for (String commonPrefix : listing.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }Call the GetBucketV2 (ListObjectsV2) operation to list all objects in a bucket
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // List objects. ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName); ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request); // Traverse all objects. System.out.println("Objects:"); for (OSSObjectSummary objectSummary : result.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all commonPrefix elements. System.out.println("CommonPrefixes:"); for (String commonPrefix : result.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }Response
The following response is returned when you call the preceding two operations to list all objects in the bucket:
Objects: fun/movie/001.avi fun/movie/007.avi fun/test.jpg oss.jpg CommonPrefixes:
List all objects in the specified directory
Call the GetBucket (ListObjects) operation to list all objects in a specific directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // Create a ListObjectsRequest request. ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName); // Set prefix to fun/ to list all objects in the fun/ directory. listObjectsRequest.setPrefix("fun/"); // Lists all objects in the fun/ directory. ObjectListing listing = ossClient.listObjects(listObjectsRequest); // Traverse all objects. System.out.println("Objects:"); for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all commonPrefix elements. System.out.println("\nCommonPrefixes:"); for (String commonPrefix : listing.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }Call the GetBucketV2 (ListObjectsV2) operation to list all objects in a specific directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // Create a ListObjectsV2Request request to list objects. ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName); // Set prefix to fun/ to list all objects in the fun/ directory. listObjectsV2Request.setPrefix("fun/"); // Initiate a list request. ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request); // Traverse all objects. System.out.println("Objects:"); for (OSSObjectSummary objectSummary : result.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all commonPrefix elements. System.out.println("\nCommonPrefixes:"); for (String commonPrefix : result.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }The following response is returned when you call the preceding two operations to list all objects in the specified directory:
Objects: fun/movie/001.avi fun/movie/007.avi fun/test.jpg CommonPrefixes:
List objects and subdirectories in a directory
Call the GetBucket (ListObjects) operation to list objects and subdirectories in a directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // Create a ListObjectsRequest request. ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName); // Set delimiter to a forward slash (/). listObjectsRequest.setDelimiter("/"); // List all objects and subdirectories in the fun/ directory. listObjectsRequest.setPrefix("fun/"); ObjectListing listing = ossClient.listObjects(listObjectsRequest); // Traverse all objects. System.out.println("Objects:"); // In the response, objectSummaries lists the objects in the fun/ directory. for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all commonPrefix elements. System.out.println("\nCommonPrefixes:"); // CommonPrefixes lists all subdirectories in the fun/ directory. The fun/movie/001.avi and fun/movie/007.avi objects are not listed because they are in the movie subdirectory of the fun/ directory. for (String commonPrefix : listing.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }Call the GetBucketV2 (ListObjectsV2) operation to list objects and subdirectories in a directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { // Create a ListObjectsV2Request request. ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName); // Set prefix to fun/ to list all objects and subdirectories in the fun/ directory. listObjectsV2Request.setPrefix("fun/"); // Set the delimiter to a forward slash (/). listObjectsV2Request.setDelimiter("/"); // Initiate the request. ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request); // Traverse all objects. System.out.println("Objects:"); // In the response, objectSummaries lists the objects in the fun/ directory. for (OSSObjectSummary objectSummary : result.getObjectSummaries()) { System.out.println(objectSummary.getKey()); } // Traverse all commonPrefix elements. System.out.println("\nCommonPrefixes:"); // CommonPrefixes lists all subdirectories in the fun/ directory. The fun/movie/001.avi and fun/movie/007.avi objects are not listed because they are in the movie/ subdirectory of the fun/ directory. for (String commonPrefix : result.getCommonPrefixes()) { System.out.println(commonPrefix); } } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } }The following response is returned when you call the preceding two operations to list objects and subdirectories in a specific directory:
Objects: fun/test.jpg CommonPrefixes: fun/movie/
List the sizes of objects in a specific directory
Call the GetBucket (ListObjects) operation to list the sizes of objects in a specific directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; import java.util.List; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. If you want to traverse the sizes of objects and directories within the root directory, leave this parameter empty. String keyPrefix = "exampledir/object"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { ObjectListing objectListing = null; do { // By default, 100 objects or directories are listed each time. ListObjectsRequest request = new ListObjectsRequest(bucketName).withDelimiter("/").withPrefix(keyPrefix); if (objectListing != null) { request.setMarker(objectListing.getNextMarker()); } objectListing = ossClient.listObjects(request); List<String> folders = objectListing.getCommonPrefixes(); for (String folder : folders) { System.out.println(folder + " : " + (calculateFolderLength(ossClient, bucketName, folder) / 1024) + "KB"); } List<OSSObjectSummary> sums = objectListing.getObjectSummaries(); for (OSSObjectSummary s : sums) { System.out.println(s.getKey() + " : " + (s.getSize() / 1024) + "KB"); } } while (objectListing.isTruncated()); } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } // Query the sizes of objects within a specified directory in a bucket. private static long calculateFolderLength(OSS ossClient, String bucketName, String folder) { long size = 0L; ObjectListing objectListing = null; do { // The default value of MaxKeys is 100. The maximum value of MaxKeys is 1000. ListObjectsRequest request = new ListObjectsRequest(bucketName).withPrefix(folder).withMaxKeys(1000); if (objectListing != null) { request.setMarker(objectListing.getNextMarker()); } objectListing = ossClient.listObjects(request); List<OSSObjectSummary> sums = objectListing.getObjectSummaries(); for (OSSObjectSummary s : sums) { size += s.getSize(); } } while (objectListing.isTruncated()); return size; } }Call the GetBucketV2 (ListObjectsV2) operation to list the sizes of objects in a specific directory
import com.aliyun.oss.*; import com.aliyun.oss.common.auth.*; import com.aliyun.oss.common.comm.SignVersion; import com.aliyun.oss.model.*; import java.util.List; public class Demo { public static void main(String[] args) throws Exception { // Specify the endpoint of the region. In this example, the endpoint of the China (Hangzhou) region is used. String endpoint = "https://oss-cn-hangzhou.aliyuncs.com"; // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider(); // Specify the bucket name. Example: examplebucket. String bucketName = "examplebucket"; // Specify the prefix that is contained in the names of the objects. Example: exampledir/object. If you want to traverse the sizes of objects and directories in the root directory, leave this parameter empty. String keyPrefix = "exampledir/object"; // Specify the region of the bucket. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. String region = "cn-hangzhou"; // Create an OSSClient instance. ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration(); clientBuilderConfiguration.setSignatureVersion(SignVersion.V4); OSS ossClient = OSSClientBuilder.create() .endpoint(endpoint) .credentialsProvider(credentialsProvider) .clientConfiguration(clientBuilderConfiguration) .region(region) .build(); try { ListObjectsV2Result result = null; do { // By default, 100 objects or directories are listed each time. ListObjectsV2Request request = new ListObjectsV2Request(bucketName).withDelimiter("/").withPrefix(keyPrefix); if (result != null) { request.setContinuationToken(result.getNextContinuationToken()); } result = ossClient.listObjectsV2(request); List<String> folders = result.getCommonPrefixes(); for (String folder : folders) { System.out.println(folder + " : " + (calculateFolderLength(ossClient, bucketName, folder) / 1024) + "KB"); } List<OSSObjectSummary> sums = result.getObjectSummaries(); for (OSSObjectSummary s : sums) { System.out.println(s.getKey() + " : " + (s.getSize() / 1024) + "KB"); } } while (result.isTruncated()); } catch (OSSException oe) { System.out.println("Caught an OSSException, which means your request made it to OSS, " + "but was rejected with an error response for some reason."); System.out.println("Error Message:" + oe.getErrorMessage()); System.out.println("Error Code:" + oe.getErrorCode()); System.out.println("Request ID:" + oe.getRequestId()); System.out.println("Host ID:" + oe.getHostId()); } catch (ClientException ce) { System.out.println("Caught an ClientException, which means the client encountered " + "a serious internal problem while trying to communicate with OSS, " + "such as not being able to access the network."); System.out.println("Error Message:" + ce.getMessage()); } finally { if (ossClient != null) { ossClient.shutdown(); } } } // Query the sizes of objects within a specified directory in a bucket. private static long calculateFolderLength(OSS ossClient, String bucketName, String folder) { long size = 0L; ListObjectsV2Result result = null; do { // The default value of maxKeys is 100. The maximum value of maxKeys is 1000. ListObjectsV2Request request = new ListObjectsV2Request(bucketName).withPrefix(folder).withMaxKeys(1000); if (result != null) { request.setContinuationToken(result.getNextContinuationToken()); } result = ossClient.listObjectsV2(request); List<OSSObjectSummary> sums = result.getObjectSummaries(); for (OSSObjectSummary s : sums) { size += s.getSize(); } } while (result.isTruncated()); return size; } }
References
For the complete sample code for listing objects, see GitHub sample.
For more information about the API operations for listing objects, see GetBucket (ListObjects) and ListObjectsV2 (GetBucketV2).
For more information about operations related to listing and managing LiveChannel files, see LiveChannel management.