Object Storage Service:Gerencie links simbólicos com o OSS SDK para Java 1.0

Notas de uso

• Este tópico utiliza o endpoint público da região China (Hangzhou). Para acessar o OSS a partir de outros serviços Alibaba Cloud na mesma região, use um endpoint interno. Para mais detalhes sobre regiões e endpoints compatíveis, consulte Regions and endpoints.

• Este tópico obtém as credenciais de acesso a partir de variáveis de ambiente. Para mais informações, consulte 配置访问凭证.

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

• Para criar um link simbólico, você precisa da permissão oss:PutObject. Para consultar um link simbólico, você precisa da permissão oss:GetObject. Para mais informações, consulte Grant a custom policy.

Crie um link simbólico

O código de exemplo a seguir mostra como criar um link simbólico:

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 {
        // 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 name of the symbolic link that you want to create. 
        String symLink = "yourSymLink";
        // Specify the name of the object to which you want the symbolic link to point. 
        String destinationObjectName = "yourDestinationObjectName";
        // 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 {
            // Create metadata for the object that you want to upload. 
            ObjectMetadata metadata = new ObjectMetadata();
            metadata.setContentType("text/plain");
            // Set the property parameter for the user metadata to property-value. 
            metadata.addUserMetadata("property", "property-value");

            // Specify whether to overwrite the object that has the same name as the symbolic link. 
            // metadata.setHeader("x-oss-forbid-overwrite", "true");
            // Specify the access control list (ACL) of the object. 
            // metadata.setHeader(OSSHeaders.OSS_OBJECT_ACL, CannedAccessControlList.Default);
            // Specify the storage class of the object. 
            // metadata.setHeader(OSSHeaders.OSS_STORAGE_CLASS, StorageClass.Standard);

            // Create a CreateSymlinkRequest to create the symbolic link. 
            CreateSymlinkRequest createSymlinkRequest = new CreateSymlinkRequest(bucketName, symLink, destinationObjectName);

            // Configure the metadata. 
            createSymlinkRequest.setMetadata(metadata);

            // Create the symbolic link. 
            ossClient.createSymlink(createSymlinkRequest);

        } 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();
            }
        }
    }
}            

Consulte um link simbólico

Para consultar um link simbólico, você precisa ter permissão de leitura sobre ele. O código de exemplo a seguir mostra como consultar um link simbólico e o nome do objeto para o qual ele aponta:

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 {
        // 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 name of the symbolic link that you want to query. 
        String symLink = "yourSymLink";
        // 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 {
            // Query the symbolic link and the name of the object to which the symbolic link points. 
            OSSSymlink symbolicLink = ossClient.getSymlink(bucketName, symLink);
            System.out.println(symbolicLink.getSymlink());
            System.out.println(symbolicLink.getTarget());
            System.out.println(symbolicLink.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();
            }
        }
    }
}          

Referências

• Para mais informações sobre a operação de API usada para criar um link simbólico, consulte PutSymlink.

• Para mais informações sobre a operação de API usada para consultar um link simbólico, consulte GetSymlink.