In a versioned bucket, the storage classes of different versions of an object can be different. By default, when you perform the RestoreObject operation on an object, the current version of the object is restored. You can specify a version ID in the request to restore the specified version of an object.

Sample code

The following code provides an example on how to restore an object:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
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";
        // The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in Object Storage Service (OSS) is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
        String accessKeyId = "yourAccessKeyId";
        String accessKeySecret = "yourAccessKeySecret";
        // Specify the bucket name. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the full path of the object. The full path of the object cannot contain the bucket name. 
        String objectName = "exampledir/object";
        // Specify the version ID of the Archive object that you want to restore. 
        String versionId = "CAEQMxiBgICAof2D0BYiIDJhMGE3N2M1YTI1NDQzOGY5NTkyNTI3MGYyMzJm****";

        // Create an OSSClient instance. 
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);

        try {
            // Query part of metadata of the specified version of the object. 
            GenericRequest getObjectMetadataRequest = new GenericRequest(bucketName,objectName, versionId);
            ObjectMetadata objectMetadata = ossClient.getObjectMetadata(getObjectMetadataRequest);

            // Check whether the specified version of the object is an Archive object. 
            StorageClass storageClass = objectMetadata.getObjectStorageClass();
            System.out.println("object storage class:" + objectMetadata.getObjectStorageClass());
            if (storageClass == StorageClass.Archive) {
                // Restore the object. 
                GenericRequest genericRequest = new GenericRequest(bucketName, objectName, versionId);
                RestoreObjectResult restoreObjectResult = ossClient.restoreObject(genericRequest);
                System.out.println("restor versionid: " + restoreObjectResult.getVersionId());

                // Wait until the object is restored. 
                do {
                    Thread.sleep(1000);
                    objectMetadata = ossClient.getObjectMetadata(getObjectMetadataRequest);
                    System.out.println("is competed:" + objectMetadata.isRestoreCompleted());
                } while (!objectMetadata.isRestoreCompleted());
            }

            // Specify the version ID of the object that you want to restore. 
            GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, objectName);
            getObjectRequest.setVersionId(versionId);
            OSSObject ossObject = ossClient.getObject(getObjectRequest);
            ossObject.getObjectContent().close();
        } 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();
            }
        }
    }
}

References

For more information about the API operation that you can call to restore an object, see RestoreObject.