Performing a Multipart Copy

If you have any questions during development, post them on the Issues page of GitHub. For details about parameters and usage of each API, see the API Reference.

As a special case of multipart upload, multipart copy implements multipart upload by copying the whole or partial object in a bucket. You can call ObsClient.copyPart to copy parts.

This example copies object sourceobjectname from bucket sourcebucketname to bucket destbucketname as object destobjectname.

The example code is as follows:

// Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables ACCESS_KEY_ID and SECRET_ACCESS_KEY_ID.
// Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/intl/en-us/usermanual-ca/ca_01_0003.html.
String ak = System.getenv("ACCESS_KEY_ID");
String sk = System.getenv("SECRET_ACCESS_KEY_ID");
String endPoint = "https://your-endpoint";
final String destBucketName = "destbucketname";
final String destObjectKey = "destobjectname";
final String sourceBucketName = "sourcebucketname";
final String sourceObjectKey = "sourceobjectname";
// Create an instance of ObsClient.
final ObsClient obsClient = new ObsClient(ak, sk, endPoint);

// Initialize the thread pool.
ExecutorService executorService = Executors.newFixedThreadPool(20);

// Initiate a multipart upload.
InitiateMultipartUploadRequest request = new InitiateMultipartUploadRequest(destBucketName, destObjectKey);
InitiateMultipartUploadResult result = obsClient.initiateMultipartUpload(request);

final String uploadId = result.getUploadId();
Log.i("CopyPart","\t"+ uploadId + "\n");

// Obtain information about the large object.
ObjectMetadata metadata = obsClient.getObjectMetadata(sourceBucketName, sourceObjectKey);
// Set the part size for copying to 100 MB.
long partSize = 100 * 1024 * 1024L;
long objectSize = metadata.getContentLength();

// Calculate the number of parts to be copied.
long partCount = objectSize % partSize == 0 ? objectSize / partSize : objectSize / partSize + 1;

final List<PartEtag> partEtags = Collections.synchronizedList(new ArrayList<PartEtag>());

// Concurrently copy parts.
for (int i = 0; i < partCount; i++)
{
// Start position for copying
    final long rangeStart = i * partSize;
// End position for copying
    final long rangeEnd = (i + 1 == partCount) ? objectSize - 1 : rangeStart + partSize - 1;
// Part number
    final int partNumber = i + 1;
    executorService.execute(new Runnable()
    {
        
        @Override
        public void run()
        {
            CopyPartRequest request = new CopyPartRequest();
            request.setUploadId(uploadId);
            request.setSourceBucketName(sourceBucketName);
            request.setSourceObjectKey(sourceObjectKey);
            request.setDestinationBucketName(destBucketName);
            request.setDestinationObjectKey(destObjectKey);
            request.setByteRangeStart(rangeStart);
            request.setByteRangeEnd(rangeEnd);
            request.setPartNumber(partNumber);
            CopyPartResult result;
            try
            {
                result = obsClient.copyPart(request);
                Log.i("CopyPart","Part#" + partNumber + " done\n");
                partEtags.add(new PartEtag(result.getEtag(), result.getPartNumber()));
            }
            catch (ObsException e)
            {
                Log.e("CopyPart", e.getMessage(), e);
            }
        }
    });
}

// Wait until the copy is complete.
executorService.shutdown();
while (!executorService.isTerminated())
{
    try
    {
        executorService.awaitTermination(5, TimeUnit.SECONDS);
    }
    catch (InterruptedException e)
    {
        Log.e("CopyPart", e.getMessage(), e);
    }
}

// Combine parts.
CompleteMultipartUploadRequest completeMultipartUploadRequest =
    new CompleteMultipartUploadRequest(destBucketName, destObjectKey, uploadId, partEtags);
obsClient.completeMultipartUpload(completeMultipartUploadRequest);

Use the PartNumber parameter to specify the part number, the UploadId parameter to specify the globally unique ID for the multipart upload, the CopySource parameter to specify the information about the source object, and the CopySourceRange parameter to specify the byte range to copy.