Object Storage Service:Resumable download (Android SDK)

Prerequisites

Before you begin, ensure that you have:

• An OSSClient instance initialized using a custom domain name or Security Token Service (STS). See Initialization

Download an object

ResumableDownloadRequest splits the object into parts and downloads each part independently. When a download is interrupted, the next attempt reads the checkpoint file and resumes from the last completed part.

// Full path of the object in the bucket. Do not include the bucket name.
String objectKey = "exampledir/exampleobject.txt";
// Full path of the local file where the downloaded content is saved.
String localFile = "/storage/emulated/0/oss/examplefile.txt";

ResumableDownloadRequest request = new ResumableDownloadRequest(bucketName, objectKey, localFile);

// Set the part size in bytes. Default: 256 KB (256 * 1024).
request.setPartSize(256 * 1024);

// Enable resumable download. OSS saves a checkpoint file after each part completes.
// If the download is interrupted, the next attempt reads the checkpoint file and skips already-downloaded parts.
request.setEnableCheckPoint(true);

// Directory where the checkpoint file is stored. Required to resume after an interruption.
request.setCheckPointFilePath("/storage/emulated/0/oss");

// Track download progress.
request.setProgressListener(new OSSProgressCallback() {
    @Override
    public void onProgress(Object request, long currentSize, long totalSize) {
        Log.d("ResumableDownload", "currentSize: " + currentSize + " totalSize: " + totalSize);
    }
});

OSSAsyncTask task = oss.asyncResumableDownload(request, new OSSCompletedCallback<ResumableDownloadRequest, ResumableDownloadResult>() {
    @Override
    public void onSuccess(ResumableDownloadRequest request, ResumableDownloadResult result) {
        Log.d("ResumableDownload", "DownloadSuccess");
    }

    @Override
    public void onFailure(ResumableDownloadRequest request, ClientException clientException, ServiceException serviceException) {
        if (clientException != null) {
            // A client-side error occurred, such as a network failure.
            clientException.printStackTrace();
        }
        if (serviceException != null) {
            // A server-side error occurred.
            Log.e("ErrorCode", serviceException.getErrorCode());
            Log.e("RequestId", serviceException.getRequestId());
            Log.e("HostId", serviceException.getHostId());
            Log.e("RawMessage", serviceException.getRawMessage());
        }
    }
});

What's next

• Complete sample code: ResumableDownloadTest on GitHub

• Underlying API operation: GetObject

• OSSClient setup: Initialization