// Create a TransferManager instance, which is used to call the advanced API later.
TransferManager createTransferManager() {
    // Create a COSClient instance, which is the foundation for accessing COS services.
    // For detailed code, refer to this page: Simple Operations -> Create COSClient
    COSClient cosClient = createCOSClient();

    // Customize the thread pool size. It is recommended to set it to 16 or 32 when the client and COS network are sufficient (e.g., using Tencent Cloud's CVM for same-region COS uploads), which allows for more efficient utilization of network resources.
    // For situations where public network transmission is used and the network bandwidth quality is not high, it is recommended to reduce this value to avoid request timeouts due to slow network speed.
    ExecutorService threadPool = Executors.newFixedThreadPool(32);

    // Pass in a thread pool. If no thread pool is provided, TransferManager will create a single-threaded thread pool by default.
    TransferManager transferManager = new TransferManager(cosClient, threadPool);

    return transferManager;
}

void shutdownTransferManager(TransferManager transferManager) {
    // If the parameter is set to true, the internal COSClient instance within the transferManager will also be closed.
    // If the parameter is set to false, the internal COSClient instance within transferManager will not be closed.
    transferManager.shutdownNow(true);
}

public Download download(final GetObjectRequest getObjectRequest, final File file);

// Before using the advanced API, ensure that the process contains a TransferManager instance. If such an instance does not exist, create one.
// For the detailed code, see "Advanced APIs -> Creating a TransferManager instance" on this page.
TransferManager transferManager = createTransferManager();

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The Object Key is the unique identifier for an object within a bucket. For more information, please refer to [Object Key](https://cloud.tencent.com/document/product/436/13324).
String key = "exampleobject";
// Path to the local file
String localFilePath = "/path/to/localFile";
File downloadFile = new File(localFilePath);

GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
try {
    // Returns an asynchronous Download result, which can be synchronously called using waitForCompletion to wait for the download to finish. On success, it returns void; on failure, it throws an exception.
    Download download = transferManager.download(getObjectRequest, downloadFile);
    download.waitForCompletion();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// After confirming that the transferManager instance is no longer in use by the current process, close it.
// For the detailed code, see "Advanced APIs -> Closing a TransferManager instance" on this page.
shutdownTransferManager(transferManager);

public Download download(final GetObjectRequest getObjectRequest, final File file,
        boolean resumableDownload);

public Download download(final GetObjectRequest getObjectRequest, final File file,
        boolean resumableDownload, String resumableTaskFile,
        int multiThreadThreshold, int partSize);

// Before using the advanced API, ensure that the process contains a TransferManager instance. If such an instance does not exist, create one.
// For the detailed code, see "Advanced APIs -> Creating a TransferManager instance" on this page.
TransferManager transferManager = createTransferManager();

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The Object Key is the unique identifier for an object within a bucket. For more information, please refer to [Object Key](https://cloud.tencent.com/document/product/436/13324).
String key = "exampleobject";
// Path to the local file
String localFilePath = "/path/to/localFile";
File downloadFile = new File(localFilePath);

GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
try {
    // Returns an asynchronous Download result, which can be synchronously called using waitForCompletion to wait for the download to finish. On success, it returns void; on failure, it throws an exception.
    Download download = transferManager.download(getObjectRequest, downloadFile, true);
    download.waitForCompletion();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// After confirming that the transferManager instance is no longer in use by the current process, close it.
// For the detailed code, see "Advanced APIs -> Closing a TransferManager instance" on this page.
shutdownTransferManager(transferManager);

public Download download(final GetObjectRequest getObjectRequest, final File file);

// You can adjust the following sample code as needed to form your own code.
void showTransferProgress(Transfer transfer) {
    System.out.println(transfer.getDescription());

    // transfer.isDone() checks if the download is completed
    while (transfer.isDone() == false) {
        try {
            // Retrieve progress every 2 seconds
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            return;
        }

        TransferProgress progress = transfer.getProgress();
        long sofar = progress.getBytesTransferred();
        long total = progress.getTotalBytesToTransfer();
        double pct = progress.getPercentTransferred();
        System.out.printf("upload progress: [%d / %d] = %.02f%%\n", sofar, total, pct);
    }

    // Completed successfully, or Failed
    System.out.println(transfer.getState());
}

// Before using the advanced API, ensure that the process contains a TransferManager instance. If such an instance does not exist, create one.
// For the detailed code, see "Advanced APIs -> Creating a TransferManager instance" on this page.
TransferManager transferManager = createTransferManager();

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The Object Key is the unique identifier for an object within a bucket. For more information, please refer to [Object Key](https://cloud.tencent.com/document/product/436/13324).
String key = "exampleobject";
// Path to the local file
String localFilePath = "/path/to/localFile";
File downloadFile = new File(localFilePath);

GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
try {
    // Returns an asynchronous Download result, which can be synchronously called using waitForCompletion to wait for the download to finish. On success, it returns void; on failure, it throws an exception.
    Download download = transferManager.download(getObjectRequest, downloadFile);
    // Print the download progress until the download is complete
    showTransferProgress(download);
    // Capture any potential exceptions here
    download.waitForCompletion();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// After confirming that the transferManager instance is no longer in use by the current process, close it.
// For the detailed code, see "Advanced APIs -> Closing a TransferManager instance" on this page.
shutdownTransferManager(transferManager);

public Download download(final GetObjectRequest getObjectRequest, final File file);

// Before using the advanced API, ensure that the process contains a TransferManager instance. If such an instance does not exist, create one.
// For the detailed code, see "Advanced APIs -> Sample code: Creating a TransferManager instance" on this page.
TransferManager transferManager = createTransferManager();

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The Object Key is the unique identifier for an object within a bucket. For more information, please refer to [Object Key](https://cloud.tencent.com/document/product/436/13324).
String key = "exampleobject";
// Path to the local file
String localFilePath = "/path/to/localFile";
File downloadFile = new File(localFilePath);
GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);

try {
    // Returns an asynchronous result (copy), which can be synchronously called using waitForCompletion to wait for the download to finish. On success, it returns void; on failure, it throws an exception.
    Download download = transferManager.download(getObjectRequest, downloadFile);
    // Wait for 3 seconds, then download a portion
    Thread.sleep(3000L);
    // Pause download and obtain a PersistableUpload instance for subsequent resumption
    PersistableDownload persistableDownload = download.pause();
    // Complex pause and resume usage:
    // PersistableDownload instances can be serialized and stored, then deserialized later to resume the download.
    // persistableDownload.serialize(out);
    // Continue downloading
    download = transferManager.resumeDownload(persistableDownload);
    // Capture potential exceptions
    download.waitForCompletion();

    // Or directly cancel this download
    // upload.abort();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// After confirming that the transferManager instance is no longer in use by the current process, close it.
// For the detailed code, see "Advanced APIs -> Sample code: Closing a TransferManager instance" on the current page.
shutdownTransferManager(transferManager);

public MultipleFileDownload downloadDirectory(String bucketName, String keyPrefix,
        File destinationDirectory) {

// Before using the advanced API, ensure that the process contains a TransferManager instance. If such an instance does not exist, create one.
// For the detailed code, see "Advanced APIs -> Sample code: Creating a TransferManager instance" on this page.
TransferManager transferManager = createTransferManager();
// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";

// Set the prefix of objects to download (similar to downloading a directory in COS). If this parameter is set to "", the entire bucket will be downloaded.
String cos_path = "/prefix";
// Absolute path of the destination folder
String dir_path = "/to/mydir";

try {
    // Returns an asynchronous result 'download', which can be synchronously called using 'waitForUploadResult' to wait for the download to complete.
    MultipleFileDownload download = transferManager.downloadDirectory(bucketName, cos_path, new File(dir_path));

    // You can choose to view the download progress
    showTransferProgress(download);

    // Or wait for completion in a blocking manner
    download.waitForCompletion();

    System.out.println("download directory done.");
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// After confirming that the transferManager instance is no longer in use by the current process, close it.
// For the detailed code, see "Advanced APIs -> Sample code: Closing a TransferManager instance" on the current page.
shutdownTransferManager(transferManager);

// Create a COSClient instance, which is used to initiate requests later.
COSClient createCOSClient() {
    // Set user identity information.
    // To view and manage SECRETID and SECRETKEY, please log in to the Access Management Console at https://console.cloud.tencent.com/cam/capi
    String secretId = System.getenv("secretId"); // User's SecretId, it is recommended to use a sub-account key, following the principle of least privilege to reduce usage risks. For obtaining a sub-account key, please refer to https://cloud.tencent.com/document/product/598/37140
    String secretKey = System.getenv("secretKey"); // User's SecretKey, it is recommended to use a sub-account key, following the principle of least privilege to reduce usage risks. For obtaining a sub-account key, please refer to https://cloud.tencent.com/document/product/598/37140
    COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);

    // ClientConfig contains the client settings for subsequent requests to COS:
    ClientConfig clientConfig = new ClientConfig();

    // Set the bucket region
    // For COS_REGION, please refer to https://cloud.tencent.com/document/product/436/6224
    clientConfig.setRegion(new Region("COS_REGION"));

    // Set the request protocol, either HTTP or HTTPS
    // For versions 5.6.53 and below, it is recommended to use the HTTPS protocol.
    // Version 5.6.54 and higher, HTTPS is used by default.
    clientConfig.setHttpProtocol(HttpProtocol.https);

    // The following settings are optional:

    // Set socket read timeout, default is 30 seconds
    clientConfig.setSocketTimeout(30*1000);
    // Set connection establishment timeout, default is 30 seconds
    clientConfig.setConnectionTimeout(30*1000);

    // Set the HTTP proxy, IP, and port if needed.
    clientConfig.setHttpProxyIp("httpProxyIp");
    clientConfig.setHttpProxyPort(80);

    // Create a COS client.
    return new COSClient(cred, clientConfig);
}


// Create a COSClient instance, which is used to initiate requests later.
COSClient createCOSClient() {
    // Here, the temporary key must have already been obtained.
    // For generating temporary keys, refer to https://cloud.tencent.com/document/product/436/14048#cos-sts-sdk
    String tmpSecretId = "TMPSECRETID";
    String tmpSecretKey = "TMPSECRETKEY";
    String sessionToken = "SESSIONTOKEN";

    COSCredentials cred = new BasicSessionCredentials(tmpSecretId, tmpSecretKey, sessionToken);

    // ClientConfig contains the client settings for subsequent requests to COS:
    ClientConfig clientConfig = new ClientConfig();

    // Set the bucket region
    // For COS_REGION, please refer to https://cloud.tencent.com/document/product/436/6224
    clientConfig.setRegion(new Region("COS_REGION"));

    // Set the request protocol, either HTTP or HTTPS
    // For versions 5.6.53 and below, it is recommended to use the HTTPS protocol.
    // Version 5.6.54 and higher, HTTPS is used by default.
    clientConfig.setHttpProtocol(HttpProtocol.https);

    // The following settings are optional:

    // Set socket read timeout, default is 30 seconds
    clientConfig.setSocketTimeout(30*1000);
    // Set connection establishment timeout, default is 30 seconds
    clientConfig.setConnectionTimeout(30*1000);

    // Set the HTTP proxy, IP, and port if needed.
    clientConfig.setHttpProxyIp("httpProxyIp");
    clientConfig.setHttpProxyPort(80);

    // Create a COS client.
    return new COSClient(cred, clientConfig);
}

public COSObject getObject(GetObjectRequest getObjectRequest)
            throws CosClientException, CosServiceException;

// Before using the COS API, ensure that the process contains a COSClient instance. If such an instance does not exist, create one.
// For the detailed code, see "Simple Operations -> Creating a COSClient instance" on the current page.
COSClient cosClient = createCOSClient();

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The Object Key is the unique identifier for an object within a bucket. For more information, please refer to [Object Key](https://cloud.tencent.com/document/product/436/13324).
String key = "exampleobject";

GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
COSObjectInputStream cosObjectInput = null;

try {
    COSObject cosObject = cosClient.getObject(getObjectRequest);
    cosObjectInput = cosObject.getObjectContent();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

// Process the stream for the download.
// Here, the stream is read directly. You can process it according to the actual situation.
byte[] bytes = null;
try {
    bytes = IOUtils.toByteArray(cosObjectInput);
} catch (IOException e) {
    e.printStackTrace();
} finally {
    // Be sure to call close() after using the stream
    cosObjectInput.close(); 
}

// Do not close the COSClient instance before the stream processing is completed.
// After confirming that the current process no longer uses the cosClient instance, close it.
cosClient.shutdown();