次の例では、Amazon S3 の下位 Java API を使用してマルチパートコピーを実行する方法を示します。作業サンプルの作成およびテストの手順については、「AWS SDK for Java のデベロッパーガイド」の「使用開始」を参照してください。
import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.*;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class LowLevelMultipartCopy {
public static void main(String[] args) throws IOException {
Regions clientRegion = Regions.DEFAULT_REGION;
String sourceBucketName = "*** Source bucket name ***";
String sourceObjectKey = "*** Source object key ***";
String destBucketName = "*** Target bucket name ***";
String destObjectKey = "*** Target object key ***";
try {
AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
.withCredentials(new ProfileCredentialsProvider())
.withRegion(clientRegion)
.build();
// Initiate the multipart upload.
InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(destBucketName,
destObjectKey);
InitiateMultipartUploadResult initResult = s3Client.initiateMultipartUpload(initRequest);
// Get the object size to track the end of the copy operation.
GetObjectMetadataRequest metadataRequest = new GetObjectMetadataRequest(sourceBucketName, sourceObjectKey);
ObjectMetadata metadataResult = s3Client.getObjectMetadata(metadataRequest);
long objectSize = metadataResult.getContentLength();
// Copy the object using 5 MB parts.
long partSize = 5 * 1024 * 1024;
long bytePosition = 0;
int partNum = 1;
List<CopyPartResult> copyResponses = new ArrayList<CopyPartResult>();
while (bytePosition < objectSize) {
// The last part might be smaller than partSize, so check to make sure
// that lastByte isn't beyond the end of the object.
long lastByte = Math.min(bytePosition + partSize - 1, objectSize - 1);
// Copy this part.
CopyPartRequest copyRequest = new CopyPartRequest()
.withSourceBucketName(sourceBucketName)
.withSourceKey(sourceObjectKey)
.withDestinationBucketName(destBucketName)
.withDestinationKey(destObjectKey)
.withUploadId(initResult.getUploadId())
.withFirstByte(bytePosition)
.withLastByte(lastByte)
.withPartNumber(partNum++);
copyResponses.add(s3Client.copyPart(copyRequest));
bytePosition += partSize;
}
// Complete the upload request to concatenate all uploaded parts and make the
// copied object available.
CompleteMultipartUploadRequest completeRequest = new CompleteMultipartUploadRequest(
destBucketName,
destObjectKey,
initResult.getUploadId(),
getETags(copyResponses));
s3Client.completeMultipartUpload(completeRequest);
System.out.println("Multipart copy complete.");
} catch (AmazonServiceException e) {
// The call was transmitted successfully, but Amazon S3 couldn't process
// it, so it returned an error response.
e.printStackTrace();
} catch (SdkClientException e) {
// Amazon S3 couldn't be contacted for a response, or the client
// couldn't parse the response from Amazon S3.
e.printStackTrace();
}
}
// This is a helper function to construct a list of ETags.
private static List<PartETag> getETags(List<CopyPartResult> responses) {
List<PartETag> etags = new ArrayList<PartETag>();
for (CopyPartResult response : responses) {
etags.add(new PartETag(response.getPartNumber(), response.getETag()));
}
return etags;
}
}