Help Center> Object Storage Service> Java> Object Upload (SDK for Java)> Multipart Upload (SDK for Java)> Code Example of a Multipart Upload (SDK for Java)
Updated on 2024-06-18 GMT+08:00
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Code Example of a Multipart Upload (SDK for Java)

Multipart upload can be used when files are too large or the network condition is poor. You can use UploadPartRequest.setOffset and UploadPartRequest.setPartSize to set the start and end positions of each part. This example uploads a large file by concurrently uploading parts.

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import com.obs.services.ObsClient;
import com.obs.services.exception.ObsException;
import com.obs.services.model.CompleteMultipartUploadRequest;
import com.obs.services.model.InitiateMultipartUploadRequest;
import com.obs.services.model.InitiateMultipartUploadResult;
import com.obs.services.model.PartEtag;
import com.obs.services.model.UploadPartRequest;
import com.obs.services.model.UploadPartResult;
import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class ConcurrentUploadPart001 {
    public static void main(String[] args) {
        // Obtain an AK/SK pair using environment variables or import the AK/SK pair in other ways. Using hard coding may result in leakage.
        // Obtain an AK/SK pair on the management console.
        String ak = System.getenv("ACCESS_KEY_ID");
        String sk = System.getenv("SECRET_ACCESS_KEY_ID");
        // (Optional) If you are using a temporary AK/SK pair and a security token to access OBS, you are advised not to use hard coding, which may result in information leakage.
        // Obtain an AK/SK pair and a security token using environment variables or import them in other ways.
        String securityToken = System.getenv("SECURITY_TOKEN");
        // Enter the endpoint corresponding to the bucket. EU-Dublin is used here as an example. Replace it with the one in your actual situation.
        String endPoint = "https://obs.eu-west-101.myhuaweicloud.eu"; 
        // Obtain an endpoint using environment variables or import it in other ways.
        //String endPoint = System.getenv("ENDPOINT");
        
        // Create an ObsClient instance.
        // Use the permanent AK/SK pair to initialize the client.
        ObsClient obsClient = new ObsClient(ak, sk,endPoint);
        // Use the temporary AK/SK pair and security token to initialize the client.
        // ObsClient obsClient = new ObsClient(ak, sk, securityToken, endPoint);

        try {
            final String bucketName = "examplebucket";
            final String objectKey = "objectname";
            // Initialize the thread pool.
            ExecutorService executorService = Executors.newFixedThreadPool(20);
            final File largeFile = new File("localfile");
            // Initiate a multipart upload.
            InitiateMultipartUploadRequest request = new InitiateMultipartUploadRequest(bucketName, objectKey);
            InitiateMultipartUploadResult result = obsClient.initiateMultipartUpload(request);
            final String uploadId = result.getUploadId();
            System.out.println("\t" + uploadId + "\n");
            // Set the part size to 100 MB.
            long partSize = 100 * 1024 * 1024L;
            long fileSize = largeFile.length();
            // Calculate the number of parts to be uploaded.
            long partCount = fileSize % partSize == 0 ? fileSize / partSize : fileSize / partSize + 1;
            final List<PartEtag> partEtags = Collections.synchronizedList(new ArrayList<PartEtag>());
            // Start uploading parts concurrently.
            for (int i = 0; i < partCount; i++) {
                // Set the start position of a part in the file.
                final long offset = i * partSize;
                // Set the part size.
                final long currPartSize = (i + 1 == partCount) ? fileSize - offset : partSize;
                // Set the part number.
                final int partNumber = i + 1;
                executorService.execute(
                        new Runnable() {
                            @Override
                            public void run() {
                                UploadPartRequest uploadPartRequest = new UploadPartRequest();
                                uploadPartRequest.setBucketName(bucketName);
                                uploadPartRequest.setObjectKey(objectKey);
                                uploadPartRequest.setUploadId(uploadId);
                                uploadPartRequest.setFile(largeFile);
                                uploadPartRequest.setPartSize(currPartSize);
                                uploadPartRequest.setOffset(offset);
                                uploadPartRequest.setPartNumber(partNumber);
                                UploadPartResult uploadPartResult;
                                try {
                                    uploadPartResult = obsClient.uploadPart(uploadPartRequest);
                                    System.out.println("Part#" + partNumber + " done\n");
                                    partEtags.add(
                                            new PartEtag(uploadPartResult.getEtag(), uploadPartResult.getPartNumber()));
                                } catch (ObsException e) {
                                    e.printStackTrace();
                                }
                            }
                        });
            }
            // Wait until the upload is complete.
            executorService.shutdown();
            while (!executorService.isTerminated()) {
                try {
                    executorService.awaitTermination(5, TimeUnit.SECONDS);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            // Assemble parts.
            CompleteMultipartUploadRequest completeMultipartUploadRequest =
                    new CompleteMultipartUploadRequest(bucketName, objectKey, uploadId, partEtags);
            obsClient.completeMultipartUpload(completeMultipartUploadRequest);
            System.out.println("completeMultipartUpload successfully");
        } catch (ObsException e) {
            System.out.println("CompleteMultipartUpload failed");
            // Request failed. Print the HTTP status code.
            System.out.println("HTTP Code:" + e.getResponseCode());
            // Request failed. Print the server-side error code.
            System.out.println("Error Code:" + e.getErrorCode());
            // Request failed. Print the error details.
            System.out.println("Error Message:" + e.getErrorMessage());
            // Request failed. Print the request ID.
            System.out.println("Request ID:" + e.getErrorRequestId());
            System.out.println("Host ID:" + e.getErrorHostId());
            e.printStackTrace();
        } catch (Exception e) {
            System.out.println("completeMultipartUpload failed");
            // Print other error information.
            e.printStackTrace();
        }
    }
}