Object Storage Service:Multipart upload for OSS on CloudBox

For most use cases, ossutil is the simplest option. When you run the cp command on a large local file, ossutil 2.0 automatically applies multipart upload:

ossutil cp D:/localpath/example.iso oss://examplebucket/desfolder/

To run the three-step multipart upload manually, use the initiate-multipart-upload, upload-part, and complete-multipart-upload operations together.

Multipart upload requires Alibaba Cloud SDK for Java version 3.15.0 or later.

The following example uploads a local file in 1 MB parts:

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.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import com.aliyun.oss.common.auth.DefaultCredentialProvider;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.ClientBuilderConfiguration;
import com.aliyun.oss.common.auth.CredentialsProviderFactory;
import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;

public class Demo {

    public static void main(String[] args) throws Exception {
        // Specify the data endpoint of the OSS on CloudBox bucket.
        String endpoint = "https://cb-f8z7yvzgwfkl9q0h****.cn-hangzhou.oss-cloudbox.aliyuncs.com";
        // Obtain access credentials from environment variables.
        // Before running this code, set the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables.
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the bucket name, for example, examplebucket.
        String bucketName = "examplebucket";
        // Specify the region where the bucket is located.
        String region = "cn-hangzhou";
        // Specify the CloudBox ID.
        String cloudBoxId = "cb-f8z7yvzgwfkl9q0h****";
        // Specify the full object path, for example, exampledir/exampleobject.txt.
        // Do not include the bucket name in the path.
        String objectName = "exampledir/exampleobject.txt";

        // Create an OSSClient instance using Signature V4 and the CloudBox ID.
        // Call shutdown() when the client is no longer needed.
        ClientBuilderConfiguration conf = new ClientBuilderConfiguration();
        conf.setSignatureVersion(SignVersion.V4);
        OSS ossClient = OSSClientBuilder.create()
                .endpoint(endpoint)
                .credentialsProvider(new DefaultCredentialProvider(credentialsProvider.getCredentials()))
                .clientConfiguration(conf)
                .region(region)
                .cloudBoxId(cloudBoxId)
                .build();

        try {
            // Step 1: Initiate the multipart upload and get an upload ID.
            InitiateMultipartUploadRequest request = new InitiateMultipartUploadRequest(bucketName, objectName);
            InitiateMultipartUploadResult upresult = ossClient.initiateMultipartUpload(request);
            String uploadId = upresult.getUploadId();

            // partETags holds the ETag and part number for each uploaded part.
            List<PartETag> partETags = new ArrayList<PartETag>();
            final long partSize = 1 * 1024 * 1024L; // 1 MB per part

            // Step 2: Upload parts sequentially.
            // Parts can also be uploaded in parallel from multiple clients—OSS assembles them by part number.
            final File sampleFile = new File("D:\\localpath\\examplefile.txt");
            long fileLength = sampleFile.length();
            int partCount = (int) (fileLength / partSize);
            if (fileLength % partSize != 0) {
                partCount++;
            }

            for (int i = 0; i < partCount; i++) {
                long startPos = i * partSize;
                long curPartSize = (i + 1 == partCount) ? (fileLength - startPos) : partSize;
                InputStream instream = new FileInputStream(sampleFile);
                instream.skip(startPos);

                UploadPartRequest uploadPartRequest = new UploadPartRequest();
                uploadPartRequest.setBucketName(bucketName);
                uploadPartRequest.setKey(objectName);
                uploadPartRequest.setUploadId(uploadId);
                uploadPartRequest.setInputStream(instream);
                // Minimum part size is 100 KB, except for the last part.
                uploadPartRequest.setPartSize(curPartSize);
                // Part numbers range from 1 to 10,000. Parts outside this range return InvalidArgument.
                uploadPartRequest.setPartNumber(i + 1);

                UploadPartResult uploadPartResult = ossClient.uploadPart(uploadPartRequest);
                partETags.add(uploadPartResult.getPartETag());
            }

            // Step 3: Complete the upload. OSS verifies each part's ETag before merging.
            CompleteMultipartUploadRequest completeMultipartUploadRequest =
                    new CompleteMultipartUploadRequest(bucketName, objectName, uploadId, partETags);
            CompleteMultipartUploadResult completeMultipartUploadResult =
                    ossClient.completeMultipartUpload(completeMultipartUploadRequest);
            System.out.println(completeMultipartUploadResult.getETag());
        } catch (OSSException oe) {
            System.out.println("OSS rejected the request: " + 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("Client error (network or configuration issue): " + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}