Object Storage Service:Verificação de dados (OSS SDK for Java 1.0)

Observações de uso

• Este tópico utiliza o endpoint público da região China (Hangzhou). Para acessar o OSS a partir de outros serviços da Alibaba Cloud na mesma região, utilize um endpoint interno. Para obter detalhes sobre as regiões e endpoints suportados, consulte Regiões e endpoints.

• Neste tópico, as credenciais de acesso são obtidas a partir de variáveis de ambiente. Para mais informações, consulte Configurar credenciais de acesso.

• Este tópico demonstra a criação de uma instância OSSClient com um endpoint do OSS. Para configurações alternativas, como o uso de domínio personalizado ou autenticação com credenciais do Security Token Service (STS), consulte Configuração do cliente.

Verificação MD5

Ao incluir Content-MD5 em uma solicitação de upload, o OSS compara o hash MD5 dos dados recebidos com o valor fornecido. Se não houver correspondência, o OSS retorna um erro InvalidDigest e é necessário fazer o upload do objeto novamente.

O upload multipart também suporta verificação MD5. Chame setMd5Digest em UploadPartRequest para definir o hash MD5 de cada parte.

• Configure a verificação MD5 em uma operação PutObject:

  import com.aliyun.oss.*;
  import com.aliyun.oss.common.auth.*;
  import com.aliyun.oss.common.comm.SignVersion;
  import com.aliyun.oss.common.utils.BinaryUtil;
  import com.aliyun.oss.model.ObjectMetadata;
  import java.io.ByteArrayInputStream;
  
  public class Demo {
      public static void main(String[] args) throws Throwable {
          // 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 name of the bucket. Example: examplebucket. 
          String bucketName = "examplebucket";
          // Specify the full path of the object. Do not include the bucket name in the full path. 
          String objectName = "exampledir/object";
          // Specify the region in which the bucket is located. 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.
          // Call the shutdown method to release resources when the OSSClient is no longer in use. 
          ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
          clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
          OSS ossClient = OSSClientBuilder.create()
          .endpoint(endpoint)
          .credentialsProvider(credentialsProvider)
          .clientConfiguration(clientBuilderConfiguration)
          .region(region)               
          .build();
  
          try {
              // Upload the string. 
              String content = "Hello OSS";
  
              ObjectMetadata meta = new ObjectMetadata();
              // Configure MD5 verification. 
              String md5 = BinaryUtil.toBase64String(BinaryUtil.calculateMd5(content.getBytes()));
              meta.setContentMD5(md5);
  
              ossClient.putObject(bucketName, objectName, new ByteArrayInputStream(content.getBytes()), meta);
  
          } 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();
              }
          }
      }
  }            

• Configure a verificação MD5 em uma operação de upload multipart:

  import java.io.File;
  import java.io.FileInputStream;
  import java.io.InputStream;
  import java.util.ArrayList;
  import java.util.List;
  
  import com.aliyun.oss.ClientBuilderConfiguration;
  import com.aliyun.oss.OSS;
  import com.aliyun.oss.OSSClientBuilder;
  import com.aliyun.oss.common.auth.CredentialsProviderFactory;
  import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;
  import com.aliyun.oss.common.comm.SignVersion;
  import com.aliyun.oss.common.utils.BinaryUtil;
  import com.aliyun.oss.model.CompleteMultipartUploadRequest;
  import com.aliyun.oss.model.CompleteMultipartUploadResult;
  import com.aliyun.oss.model.InitiateMultipartUploadRequest;
  import com.aliyun.oss.model.InitiateMultipartUploadResult;
  import com.aliyun.oss.model.PartETag;
  import com.aliyun.oss.model.UploadPartRequest;
  import com.aliyun.oss.model.UploadPartResult;
  
  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 = "http://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 name of the bucket. Example: examplebucket.   
          String bucketName = "examplebucket";
          // Specify the full path of the object. Do not include the bucket name in the full path. 
          String objectName = "exampledir/object";
          // Specify the path of the local file that you want to upload. 
          String localFile = "D:\\localpath\\examplefile.txt";
          // Specify the region in which the bucket is located. 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. 
          // Call the shutdown method to release resources when the OSSClient is no longer in use.
          ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
          clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
          OSS ossClient = OSSClientBuilder.create()
          .endpoint(endpoint)
          .credentialsProvider(credentialsProvider)
          .clientConfiguration(clientBuilderConfiguration)
          .region(region)               
          .build();
          // Create an InitiateMultipartUploadRequest object. 
          InitiateMultipartUploadRequest request = new InitiateMultipartUploadRequest(bucketName, objectName);
          // Optional. Specify the storage class.
          // ObjectMetadata metadata = new ObjectMetadata();
          // metadata.setHeader(OSSHeaders.OSS_STORAGE_CLASS, StorageClass.Standard.toString());
          // request.setObjectMetadata(metadata);
          // Initiate a multipart upload task. 
          InitiateMultipartUploadResult upresult = ossClient.initiateMultipartUpload(request);
          // Obtain an upload ID. The upload ID uniquely identifies the multipart upload task. You can use the upload ID to initiate related requests such as canceling and querying a multipart upload task. 
          String uploadId = upresult.getUploadId();
          // partETags is a set of PartETags. The PartETag of a part consists of the part number and ETag value of the part. 
          List<PartETag> partETags = new ArrayList<PartETag>();
          // Calculate the total number of parts to upload. 
          final long partSize = 1 * 1024 * 1024L;   // 1MB
          final File sampleFile = new File(localFile);
          long fileLength = sampleFile.length();
          int partCount = (int) (fileLength / partSize);
          if (fileLength % partSize != 0) {
              partCount++;
          }
          // Upload all parts. 
          for (int i = 0; i < partCount; i++) {
              long startPos = i * partSize;
              long curPartSize = (i + 1 == partCount) ? (fileLength - startPos) : partSize;
              InputStream instream = new FileInputStream(sampleFile);
              InputStream instream1 = new FileInputStream(sampleFile);
           // Skip parts that have been uploaded. 
              instream.skip(startPos);
              instream1.skip(startPos);
              String md5;
              if(i==partCount-1){
           // The size of the last part is not necessarily equal to the specified part size.
                  md5 = md5(instream1,fileLength - startPos);
              }else{
                  md5 = md5(instream1,partSize);
              }
            // instream1.skip(n)
              UploadPartRequest uploadPartRequest = new UploadPartRequest();
              uploadPartRequest.setBucketName(bucketName);
              uploadPartRequest.setKey(objectName);
              uploadPartRequest.setUploadId(uploadId);
              uploadPartRequest.setInputStream(instream);
              uploadPartRequest.setMd5Digest(md5);
           // Specify the part size. Each part except the last part must be equal to or greater than 100 KB. 
              uploadPartRequest.setPartSize(curPartSize);
           // Configure part numbers. Each part is configured with a part number. The value ranges from 1 to 10000. If you configure a number beyond the range, OSS returns an InvalidArgument error code. 
              uploadPartRequest.setPartNumber( i + 1);
           // Parts are not necessarily uploaded in order and can be uploaded from different OSS clients. OSS sorts the parts based on the part numbers and combines the parts into a complete object. 
              UploadPartResult uploadPartResult = ossClient.uploadPart(uploadPartRequest);
           // System.out.println("server md5" +uploadPartResult.getETag());
           // Each time a part is uploaded, OSS returns a result that contains a PartETag. The PartETag is stored in partETags. 
              partETags.add(uploadPartResult.getPartETag());
          }
          // Create a CompleteMultipartUploadRequest object. 
          // When you call the CompleteMultipartUpload operation, you must provide all valid PartETags. After OSS receives the partETags, OSS verifies all parts one by one. After part verification is successful, OSS combines these parts into a complete object. 
          CompleteMultipartUploadRequest completeMultipartUploadRequest =
                  new CompleteMultipartUploadRequest(bucketName, objectName, uploadId, partETags);
          // Optional. Set the access control list (ACL) of the object. 
          // completeMultipartUploadRequest.setObjectACL(CannedAccessControlList.PublicRead);
          // Complete the multipart upload task. 
          CompleteMultipartUploadResult completeMultipartUploadResult = ossClient.completeMultipartUpload(completeMultipartUploadRequest);
          // Close your OSSClient. 
          ossClient.shutdown();
      }
      public static String md5(InputStream in , long length1) throws Exception{
          byte[] bytes = new byte[(int) length1];
          long length_tmp = length1;
          int readSize = in.read(bytes, (int) 0, (int) length_tmp);
          return BinaryUtil.toBase64String(BinaryUtil.calculateMd5(bytes));
      }
  }

Verificação CRC-64

A verificação CRC-64 está ativada por padrão nas operações de upload, download e cópia de objetos.

• CRC-64 no download de objetos

  Execute a verificação CRC-64 durante o download de um objeto:

  import com.aliyun.oss.*;
  import com.aliyun.oss.common.auth.*;
  import com.aliyun.oss.common.comm.SignVersion;
  import com.aliyun.oss.common.utils.IOUtils;
  import com.aliyun.oss.internal.OSSHeaders;
  import com.aliyun.oss.internal.OSSUtils;
  import com.aliyun.oss.model.GetObjectRequest;
  import com.aliyun.oss.model.OSSObject;
  import java.io.BufferedReader;
  import java.io.InputStreamReader;
  
  public class Demo {
      public static void main(String[] args) throws Throwable {
          // 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 name of the bucket. Example: examplebucket. 
          String bucketName = "examplebucket";
          // Specify the full path of the object. Do not include the bucket name in the full path. 
          String objectName = "exampledir/object";
          // Specify the region in which the bucket is located. 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.
          // Call the shutdown method to release resources when the OSSClient is no longer in use. 
          ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
          clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
          OSS ossClient = OSSClientBuilder.create()
          .endpoint(endpoint)
          .credentialsProvider(credentialsProvider)
          .clientConfiguration(clientBuilderConfiguration)
          .region(region)               
          .build();
  
          try {
              // Download the object in streaming mode. 
              GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, objectName);
              OSSObject ossObject = ossClient.getObject(bucketName, objectName);
  
              // Read the object from the stream to obtain clientCRC. 
              System.out.println("Object content:");
              BufferedReader reader = new BufferedReader(new InputStreamReader(ossObject.getObjectContent()));
              while (true) {
                  String line = reader.readLine();
                  if (line == null) break;
  
                  System.out.println("\n" + line);
              }
              // You must close the obtained stream after the object is read. Otherwise, connection leaks may occur. Consequently, no connections are available and an exception occurs. 
              reader.close();
  
              // Check whether CRC-64 is enabled on the client. By default, CRC-64 is enabled on the client. 
              Boolean isCrcCheckEnabled = ((OSSClient)ossClient).getClientConfiguration().isCrcCheckEnabled();
              // Check whether the download quest is a range download request. CRC-64 verification is not supported for range download. 
              Boolean isRangGetRequest = getObjectRequest.getHeaders().get(OSSHeaders.RANGE) != null;
  
              // Check whether the CRC-64 value in the returned result is the same as that of the downloaded object. 
              if (isCrcCheckEnabled && !isRangGetRequest) {
                  Long clientCRC = IOUtils.getCRCValue(ossObject.getObjectContent());
                  OSSUtils.checkChecksum(clientCRC, ossObject.getServerCRC(), ossObject.getRequestId());
              }
          } 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();
              }
          }
      }
  }

• CRC-64 no upload append

  Execute a verificação CRC-64 durante um upload append:

  import com.aliyun.oss.*;
  import com.aliyun.oss.common.auth.*;
  import com.aliyun.oss.common.comm.SignVersion;
  import com.aliyun.oss.model.*;
  import java.io.ByteArrayInputStream;
  
  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 name of the bucket. Example: examplebucket. 
          String bucketName = "examplebucket";
          // Specify the full path of the object. Example: exampleobject.txt. Do not include the bucket name in the full path. 
          String objectName = "exampleobject.txt";
          // Enter the content of the first append upload, such as Hello. 
          String firstAppendContent = "Hello";
          // Enter the content of the second append upload, such as World. 
          String secondAppendContent = "World";
          // Specify the region in which the bucket is located. 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. 
          // Call the shutdown method to release resources when the OSSClient is no longer in use.
          ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
          clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
          OSS ossClient = OSSClientBuilder.create()
          .endpoint(endpoint)
          .credentialsProvider(credentialsProvider)
          .clientConfiguration(clientBuilderConfiguration)
          .region(region)               
          .build();
  
          try {
              // Perform the first append operation. 
              AppendObjectRequest appendObjectRequest = new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(firstAppendContent.getBytes()));
              appendObjectRequest.setPosition(0L);
              // Set the initial CRC-64 value. OSS SDK for Java performs CRC-64 on the uploaded content by default. 
              appendObjectRequest.setInitCRC(0L);
              AppendObjectResult appendObjectResult = ossClient.appendObject(appendObjectRequest);
  
              // Perform the second append upload operation. 
              appendObjectRequest = new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(secondAppendContent.getBytes()));
              appendObjectRequest.setPosition(appendObjectResult.getNextPosition());
              // Set the CRC-64 value to that of the uploaded object. OSS SDK for Java performs CRC-64 on the uploaded content by default. 
              appendObjectRequest.setInitCRC(appendObjectResult.getClientCRC());
              ossClient.appendObject(appendObjectRequest);
          } 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();
              }
          }
      }
  }

Referências

O código de exemplo completo para verificação MD5 e CRC-64 está disponível no GitHub.