Overview

This document provides an overview of APIs and SDK code samples related to simple operations, multipart operations, and advanced APIs.

Simple operations

Multipart upload operations

Simple Operations

Querying an object list

API description

This API is used to query some or all objects in a bucket.

Method prototype

public ObjectListing listObjects(ListObjectsRequest listObjectsRequest) throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
ListObjectsRequest listObjectsRequest = new ListObjectsRequest();
// Set the bucket name.
listObjectsRequest.setBucketName(bucketName);
// The prefix indicates that the key of the object to be listed must start with this value.
listObjectsRequest.setPrefix("images/");
// Set the delimiter to "/" to list objects in the current directory. To list all objects, leave it empty.
listObjectsRequest.setDelimiter("/");
// Set the maximum number of traversed objects (up to 1,000 per listobject request).
listObjectsRequest.setMaxKeys(1000);
ObjectListing objectListing = null;
do {
    try {
        objectListing = cosClient.listObjects(listObjectsRequest);
    } catch (CosServiceException e) {
        e.printStackTrace();
        return;
    } catch (CosClientException e) {
        e.printStackTrace();
        return;
    }
    // A common prefix indicates paths that end with the delimiter. If the delimiter is set to "/", the common prefix indicates the paths of all subdirectories.
    List<String> commonPrefixs = objectListing.getCommonPrefixes();

    // The object summary shows all listed objects.
    List<COSObjectSummary> cosObjectSummaries = objectListing.getObjectSummaries();
    for (COSObjectSummary cosObjectSummary : cosObjectSummaries) {
        // File path key
        String key = cosObjectSummary.getKey();
        // File ETag
        String etag = cosObjectSummary.getETag();
        // File size
        long fileSize = cosObjectSummary.getSize();
        // File storage class
        String storageClasses = cosObjectSummary.getStorageClass();
    }

    String nextMarker = objectListing.getNextMarker();
    listObjectsRequest.setMarker(nextMarker);
} while (objectListing.isTruncated());

Parameter description

Request members:

Response description

• Success: returns ObjectListing, including all members and nextMarker.
• Failure: throws a "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Uploading an object using simple upload

API description

This API (PUT Object) is used to upload objects to the specified bucket. It can upload a local file or an input stream of a known length to COS. It is suitable for uploading small image files (below 20 MB), with a maximum of 5 GB (inclusive) supported. Please use Multipart Upload or Advanced API if the file is larger than 5 GB.

• The file length and MD5 hash are checked by default during upload (see the sample code for disabling MD5 check).
• If an object with the same key already exists in COS, it will be overwritten by the newly-uploaded one.
• Once uploaded, you can download the file by calling the GetObject API with the same key, or by generating a pre-signed URL and sending the file to another device for download (Please specify GET as the download method; see the section below for API instructions.)

Method prototype

// Method 1. Upload a local file to COS.
public PutObjectResult putObject(String bucketName, String key, File file)
            throws CosClientException, CosServiceException;
// Method 2. Upload an input stream to COS.
public PutObjectResult putObject(String bucketName, String key, InputStream input, ObjectMetadata metadata)
            throws CosClientException, CosServiceException;
// Method 3. Encapsulate the two methods above to support more fine-grained parameter control, such as content-type and content-disposition.
public PutObjectResult putObject(PutObjectRequest putObjectRequest)
            throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// Method 1. Upload a local file.
File localFile = new File(localFilePath);
String key = "exampleobject";
PutObjectResult putObjectResult = cosClient.putObject(bucketName, key, localFile);
String etag = putObjectResult.getETag();  // Obtain the file ETag.

// Method 2. Upload an input stream (The length of the input stream must be provided in advance. Otherwise, an OOM error may occur).
FileInputStream fileInputStream = new FileInputStream(localFile);
ObjectMetadata objectMetadata = new ObjectMetadata();
// Set the length of the input stream to 500.
objectMetadata.setContentLength(500);
// Set the content type. Default: application/octet-stream
objectMetadata.setContentType("application/pdf");
putObjectResult = cosClient.putObject(bucketName, key, fileInputStream, objectMetadata);
etag = putObjectResult.getETag();
// Close the input stream.

// Method 3: Provide more fine-grained control. Common settings are as follows:
// 1 storage-class. Enumerated values are `Standard` (default), `Standard_IA`, and `Archive`. For more information, please see: https://intl.cloud.tencent.com/zh/document/product/436/30925
// 2. content-type. For local file upload, the files are mapped based on the suffix by default. For example, a JPG file is mapped as image/jpeg.
// For input stream upload, the default is application/octet-stream.
// 3. Specify permissions during the upload (or call the relevant API to set an object ACL).
// 4 To disable MD5 upload verification globally, set the system environment variable. This will affect all upload verification operations, which are performed by default.
// Disable M5 verification: System.setProperty(SkipMd5CheckStrategy.DISABLE_PUT_OBJECT_MD5_VALIDATION_PROPERTY, "true");
// Enable M5 verification: System.setProperty(SkipMd5CheckStrategy.DISABLE_PUT_OBJECT_MD5_VALIDATION_PROPERTY, null);
localFile = new File(localFilePath);
key = "picture.jpg";
PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, key, localFile);
// Set the storage class to STANDARD_IA.
putObjectRequest.setStorageClass(StorageClass.Standard_IA);
// Set custom attributes (such as content-type, content-disposition).
objectMetadata = new ObjectMetadata();
// Here, set the upload bandwidth limit (in bit/s) to 10 MB/s.
putObjectRequest.setTrafficLimit(80*1024*1024);
// Set the content type. Default: application/octet-stream
objectMetadata.setContentType("image/jpeg");
putObjectRequest.setMetadata(objectMetadata);
putObjectResult = cosClient.putObject(putObjectRequest);
// Get the ETag of the object.
etag = putObjectResult.getETag();
// Get the CRC64 checksum of the object.
String crc64Ecma = putObjectResult.getCrc64Ecma();

Parameter description

Request members:

The ObjectMetadata class is used to record the metadata of an object. The main members are described below:

Response description

• Success: returns PutObjectResult, including the file ETag.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Response parameters

The PutObjectResult class is used to return result information. Its main members are described as follows:

Querying object metadata

API description

This API is used to query whether a specified object exists in a certain bucket.

Method prototype

public ObjectMetadata getObjectMetadata(String bucketName, String key)
            throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
ObjectMetadata objectMetadata = cosClient.getObjectMetadata(bucketName, key);

Parameter description

Response description

• Success: returns ObjectMetadata, including the user-defined headers and object metadata such as the ETag.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Response parameters

The ObjectMetadata class is used to record the metadata of an object. The main members are described as follows:

Downloading an object

API description

This API (GET Object) is used to download an object.

Method prototype

// Method 1. Download a file and get the input stream.
public COSObject getObject(GetObjectRequest getObjectRequest)
            throws CosClientException, CosServiceException;
// Method 2. Download the file locally.
public ObjectMetadata getObject(GetObjectRequest getObjectRequest, File destinationFile)
            throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
// Method 1. Get the input stream of the downloaded file.
GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
// Here, set the download bandwidth limit in bit/s to 10 MB/s
getObjectRequest.setTrafficLimit(80*1024*1024);
COSObject cosObject = cosClient.getObject(getObjectRequest);
COSObjectInputStream cosObjectInput = cosObject.getObjectContent();
// Download the CRC64 value of the object.
String crc64Ecma = cosObject.getObjectMetadata().getCrc64Ecma();
// Close the input stream.
cosObjectInput.close();

// Method 2. Download the file locally.
String outputFilePath = "exampleobject";
File downFile = new File(outputFilePath);
getObjectRequest = new GetObjectRequest(bucketName, key);
ObjectMetadata downObjectMeta = cosClient.getObject(getObjectRequest, downFile);

Parameter description

Request members:

Response description

• Method 1 (Get the input stream of the downloaded file)
  • Success: returns the COSObject class, including the input stream and object attributes.
  • Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.
• Method 2 (Download the file locally)
  • Success: returns objectMetadata, including the file's custom headers, content-type, and other attributes.
  • Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Response parameters

The COSObject class is used to return request results. Its main members as described as follows:

Copying an object

API description

This API (Put Object Cop) is used to copy an object. You can copy an object up to 5 GB in size across regions, accounts, and buckets, provided that you have read permission for the source file and write permission for the destination file. To copy files larger than 5 GB, use the advanced replication API.

Method prototype

public CopyObjectResult copyObject(CopyObjectRequest copyObjectRequest)
            throws CosClientException, CosServiceException

Sample request

// Intra-region and intra-account replication
// Enter the bucket name in the format of BucketName-APPID.
String srcBucketName = "sourcebucket-1250000000";
// The source file to be copied
String srcKey = "sourceObject";
// Enter the destination bucket name in the format of BucketName-APPID.
String destBucketName = "examplebucket-1250000000";
// The destination file to be copied into
String destKey = "exampleobject";
CopyObjectRequest copyObjectRequest = new CopyObjectRequest(srcBucketName, srcKey, destBucketName, destKey);
CopyObjectResult copyObjectResult = cosClient.copyObject(copyObjectRequest);

// Cross-account and cross-region replication (read permission for the source file and write permission for the destination file are required)
String srcBucketNameOfDiffAppid = "bucket-own-by-others-1251668577";
Region srcBucketRegion = new Region("ap-shanghai");
copyObjectRequest = new CopyObjectRequest(srcBucketRegion, srcBucketNameOfDiffAppid, srcKey, destBucketName, destKey);
copyObjectResult = cosClient.copyObject(copyObjectRequest);
// Get the CRC64 value of the object
String crc64Ecma = copyObjectResult.getCrc64Ecma();

Parameter description

Request members:

Response description

• Success: returns CopyObjectResult, including the ETag and other information on the new file.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Deleting a single object

API description

This API is used to delete a specified object (file/object) from a bucket.

Method prototype

public void deleteObject(String bucketName, String key)
            throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
cosClient.deleteObject(bucketName, key);

Parameter description

Response description

• Success: No value is returned.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Deleting multiple objects

API description

The API (DELETE Multiple Objects) is used to delete multiple objects.

Method prototype

public DeleteObjectsResult deleteObjects(DeleteObjectsRequest deleteObjectsRequest)
    throws MultiObjectDeleteException, CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";

DeleteObjectsRequest deleteObjectsRequest = new DeleteObjectsRequest(bucketName);
// Set the list of keys to be deleted. A maximum of 1,000 keys can be deleted at a time.
ArrayList<DeleteObjectsRequest.KeyVersion> keyList = new ArrayList<DeleteObjectsRequest.KeyVersion>();
// Pass the names of files to be deleted.
keyList.add(new DeleteObjectsRequest.KeyVersion("project/folder1/picture.jpg"));
keyList.add(new DeleteObjectsRequest.KeyVersion("project/folder2/text.txt"));
keyList.add(new DeleteObjectsRequest.KeyVersion("project/folder2/music.mp3"));
deleteObjectsRequest.setKeys(keyList);

// Delete multiple files in a single request.
try {
    DeleteObjectsResult deleteObjectsResult = cosClient.deleteObjects(deleteObjectsRequest);
    List<DeleteObjectsResult.DeletedObject> deleteObjectResultArray = deleteObjectsResult.getDeletedObjects();
} catch (MultiObjectDeleteException mde) { // If not all the objects are deleted successfully, MultiObjectDeleteException is returned
    List<DeleteObjectsResult.DeletedObject> deleteObjects = mde.getDeletedObjects();
    List<MultiObjectDeleteException.DeleteError> deleteErrors = mde.getErrors();
} catch (CosServiceException e) { // Throws a CosServiceException for other errors such as parameter errors and authentication failure
    e.printStackTrace();
    throw e;
} catch (CosClientException e) { // Throws this exception for client errors, such as COS connection failure
    e.printStackTrace();
    throw e;
}

Parameter description

Request members:

DeleteObjectsRequest.KeyVersion members are described as follows:

Response description

• Success: No value is returned.
• Failure: an error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Restoring an archived object

API description

This (POST Object restore) API is used to restore an archived object for access.

Method prototype

public void restoreObject(RestoreObjectRequest restoreObjectRequest)
    throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";

// Sets the number of days before a restored temporary copy expires to 1
RestoreObjectRequest restoreObjectRequest = new RestoreObjectRequest(bucketName, key, 1);
// Sets the restoration mode to Standard. Other alternative options include Expedited and Bulk. These three modes differ in cost and speed.
CASJobParameters casJobParameters = new CASJobParameters();
casJobParameters.setTier(Tier.Standard);
restoreObjectRequest.setCASJobParameters(casJobParameters);
cosClient.restoreObject(restoreObjectRequest);

Parameter description

Request members:

Response description

• Success: No value is returned.
• Failure: an error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Multipart operations

Operations related to multipart uploads are as follows:

• Multipart upload: initializing a multipart upload operation, uploading parts, and completing a multipart upload operation
• Resuming a multipart upload operation: querying uploaded parts, uploading remaining parts, and completing a multipart upload operation
• Deleting uploaded parts

Querying multipart uploads

API description

This API is used to query in-progress multipart uploads in a specified bucket.

Method prototype

public MultipartUploadListing listMultipartUploads(
            ListMultipartUploadsRequest listMultipartUploadsRequest)
            throws CosClientException, CosServiceException

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
ListMultipartUploadsRequest listMultipartUploadsRequest = new ListMultipartUploadsRequest(bucketName);
listMultipartUploadsRequest.setDelimiter("/");
listMultipartUploadsRequest.setMaxUploads(100);
listMultipartUploadsRequest.setPrefix("");
listMultipartUploadsRequest.setEncodingType("url");
MultipartUploadListing multipartUploadListing = cosClient.listMultipartUploads(listMultipartUploadsRequest);

Parameter description

Request members:

Response description

• Success: returns MultipartUploadListing, including the in-progress multipart uploads.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Initializing a multipart upload

API description

This API (Initiate Multipart Upload) is used to initialize a multipart upload.

Method prototype

public InitiateMultipartUploadResult initiateMultipartUpload(
    InitiateMultipartUploadRequest request) throws CosClientException, CosServiceException;

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(bucketName, key);
InitiateMultipartUploadResult initResponse = cosClient.initiateMultipartUpload(initRequest);
uploadId = initResponse.getUploadId();

Parameter description

Request members:

Response description

• Success: returns InitiateMultipartUploadResult, including the uploadId that identifies the multipart upload.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Uploading parts

This API (Upload Part) is used to upload parts in a multipart upload.

Method prototype

public UploadPartResult uploadPart(UploadPartRequest uploadPartRequest) throws CosClientException, CosServiceException;

Sample request

// Up to 10,000 parts can be uploaded, ranging from 1 MB to 5 GB in size.
// Set the size of each part to 4 MB. If there are a total of n parts, the size of part 1 through part n-1 is the same, while the last part is less than or equal to it.
partETags = new ArrayList<PartETag>();
int partNumber = 1;
int partSize = 4 * 1024 * 1024;
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
byte data[] = new byte[partSize];
ByteArrayInputStream partStream = new ByteArrayInputStream(data);
// partStream represents the input stream of the part data. The length of the input stream is the partSize.
UploadPartRequest uploadRequest = new UploadPartRequest().withBucketName(bucketName).
        withUploadId(uploadId).withKey(key).withPartNumber(partNumber).
        withInputStream(partStream).withPartSize(partSize);
UploadPartResult uploadPartResult = cosClient.uploadPart(uploadRequest);
// Get the ETag of the part.
String etag = uploadPartResult.getETag();
// Get the CRC64 value of the part.
String crc64Ecma = uploadPartResult.getCrc64Ecma();
partETags.add(new PartETag(partNumber, eTag));  // partETags records the ETags of all the uploaded parts.
// ... Upload parts with the partNumber of 2 to n

Parameter description

Request members:

Response description

• Success: returns UploadPartResult, including the ETags of the uploaded parts.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Response parameters

The UploadPartResult class is used to return request results. Its main members are described as follows:

Copying a part

API description

This API (Upload Part - Copy) is used to copy an object as a part from a source path to a destination path.

Method prototype

public CopyPartResult copyPart(CopyPartRequest copyPartRequest) throws CosClientException, CosServiceException

Sample request

// Bucket name in the format of BucketName-APPID
// Set destination bucket name, object name, and multipart upload ID.
String destinationBucketName = "examplebucket-1250000000";
String destinationTargetKey = "exampleobject";
int partNumber = 1;
CopyPartRequest copyPartRequest = new CopyPartRequest();
copyPartRequest.setDestinationBucketName(destinationBucketName);
copyPartRequest.setDestinationKey(destinationTargetKey);
copyPartRequest.setUploadId(uploadId);
copyPartRequest.setPartNumber(partNumber);
// Set the region and name of the source bucket, object name, and offset range.
String sourceBucketRegion = "COS_REGION";
String sourceBucketName = "sourcebucket-1250000000";
String sourceKey = "sourceObject";
Long firstByte = 1L;
Long lastByte = 1048576L;
copyPartRequest.setSourceBucketRegion(new Region(sourceBucketRegion));
copyPartRequest.setSourceBucketName(sourceBucketName);
copyPartRequest.setSourceKey(sourceKey);
copyPartRequest.setFirstByte(firstByte);
copyPartRequest.setLastByte(lastByte);

CopyPartResult copyPartResult = cosClient.copyPart(copyPartRequest);
partETags = new ArrayList<PartETag>();
partETags.add(copyPartResult.getPartETag());

Parameter description

Request members:

Response description

• Success: returns CopyPartResult, including the ETag of the part.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Querying uploaded parts

API description

This API (List Parts) is used to query the uploaded parts of a multipart upload.

Method prototype

public PartListing listParts(ListPartsRequest request)
            throws CosClientException, CosServiceException;

Sample request

// ListPart is used to list uploaded parts using the uploadId before a multipart upload is completed or aborted, and also to construct partEtags.
List<PartETag> partETags = new ArrayList<PartETag>();
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
ListPartsRequest listPartsRequest = new ListPartsRequest(bucketName, key, uploadId);
PartListing partListing = null;
do {
    partListing = cosClient.listParts(listPartsRequest);
    for (PartSummary partSummary : partListing.getParts()) {
        partETags.add(new PartETag(partSummary.getPartNumber(), partSummary.getETag()));
    }
    listPartsRequest.setPartNumberMarker(partListing.getNextPartNumberMarker());
} while (partListing.isTruncated());

Parameter description

Response description

• Success: returns PartListing, including the ETag and number of each part as well as the starting marker of the next list.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Completing a multipart upload

API description

This API (Complete Multipart Upload) is used to complete the multipart upload of the entire file.

Method prototype

public CompleteMultipartUploadResult completeMultipartUpload(CompleteMultipartUploadRequest request) throws CosClientException, CosServiceException;

Sample request

// Complete a multipart upload.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
CompleteMultipartUploadRequest compRequest = new CompleteMultipartUploadRequest(bucketName, key, uploadId, partETags);
CompleteMultipartUploadResult result = cosClient.completeMultipartUpload(compRequest);

Parameter description

Response description

• Success: returns CompleteMultipartUploadResult, including the ETag of the completed object.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Aborting a multipart upload

API description

This API (Abort Multipart Upload) is used to abort a multipart upload and delete the uploaded parts.

Method prototype

public void abortMultipartUpload(AbortMultipartUploadRequest request)  throws CosClientException, CosServiceException;

Sample request

// abortMultipartUpload is used to abort an uncompleted multipart upload
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
AbortMultipartUploadRequest abortMultipartUploadRequest = new AbortMultipartUploadRequest(bucketName, key, uploadId);
cosClient.abortMultipartUpload(abortMultipartUploadRequest);

Parameter description

Response description

• Success: returns no value.
• Failure: An error occurs (such as authentication failure), throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Advanced APIs (Recommended)

The advanced APIs encapsulate upload and download APIs using the TransferManger class. They have a thread pool to receive upload and download requests, so that you can choose to submit tasks asynchronously.

// We recommend setting the size of your thread pool to 16 or 32 to maximize network resource utilization, provided your client and COS networks are sufficient (for example, by using Tencent Cloud CVM and uploading to COS in the same region).
// We recommend using a smaller value to avoid timeout due to slow network speed if you are transferring data over a public network with poor bandwidth quality.
ExecutorService threadPool = Executors.newFixedThreadPool(32);
// Pass a threadpool. Otherwise, a single-thread pool will be generated in TransferManager by default.
TransferManager transferManager = new TransferManager(cosClient, threadPool);
// Set the threshold and part size for multipart upload through the advanced upload API to 10 MB.
TransferManagerConfiguration transferManagerConfiguration = new TransferManagerConfiguration();
transferManagerConfiguration.setMultipartUploadThreshold(10 * 1024 * 1024);
transferManagerConfiguration.setMinimumUploadPartSize(10 * 1024 * 1024);
transferManager.setConfiguration(transferManagerConfiguration);

Close transferManager manually after use to prevent resource leakage.

// Close TransferManger.
transferManager.shutdownNow();

Parameter description

The TransferManagerConfiguration class is used to record the configuration of advanced APIs. Its main members are described as follows:

Uploading an object

API description

This advanced version of the PUT Object API automatically determines whether to use simple or multipart upload based on the length and data type of your file, as shown below:

• Determines simple upload for stream uploads below the multipart upload threshold, OR without the Content-Length header;
• Determines multipart upload for stream uploads above the multipart upload threshold, AND without the Content-Length header;
• Determines multipart upload with concurrent threads for files with File as the data type.

Note：

For information on other configuration attributes, storage classes, and MD5 check, see PUT Object.

Method prototype

// Upload an object
public Upload upload(final PutObjectRequest putObjectRequest)
            throws CosServiceException, CosClientException;

Sample request

// Sample 1:
// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
File localFile = new File(localFilePath);
PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, key, localFile);
// Upload a local file.
Upload upload = transferManager.upload(putObjectRequest);
// Wait for the upload to finish (call waitForCompletion if you want to wait synchronously for the upload to complete).
UploadResult uploadResult = upload.waitForUploadResult();

Parameter description

Request members:

Note：

When a file is uploaded in concurrent parts, trafficLimit is the limit on the upload speed of each part. In this case, you need to adjust the number of threads in your thread pool to control the upload speed.

Response

• Success: returns Upload. You can query whether the upload is complete, or wait until the upload is finished.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Response parameters

The UploadResult class records the object upload results requested by calling the waitForUploadResult() method from the Upload class. Its main class members are as follows:

Downloading an object

API description

This API is used to download a COS object.

Method prototype

// Download an object.
public Download download(final GetObjectRequest GetObjectRequest, final File file);

Sample request

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
File localDownFile = new File(localFilePath);
GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
// Here, set the download bandwidth limit in bit/s to 10 MB/s
getObjectRequest.setTrafficLimit(80*1024*1024);
// Download a file.
Download download = transferManager.download(getObjectRequest, localDownFile);
// Wait for the upload to finish (call waitForCompletion if you want to wait synchronously for the upload to complete).
download.waitForCompletion();

Parameter description

Request members:

Response

• Success: returns Download. You can query whether the download is complete, or wait until the download is finished.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Copying an object

API description

This advanced replication API automatically determines whether to use simple replication or multipart replication based on the size of an object.

Method prototype

// Upload an object.
public Copy copy(final CopyObjectRequest copyObjectRequest);

Sample request

// The region of bucket to copy. Cross-region copy is supported.
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials srcCredentials = new BasicCOSCredentials(secretId, secretKey);
Region srcBucketRegion = new Region("COS_REGION");
// Enter the bucket name in the format of BucketName-APPID.
String srcBucketName = "sourcebucket-1250000000";
// The source file to be copied
String srcKey = "sourceObject";
// Enter the destination bucket name in the format of BucketName-APPID.
String destBucketName = "examplebucket-1250000000";
// The destination file to be copied into
String destKey = "exampleobject";
// Generate srcCOSClient to get source file information.
COSClient srcCOSClient = new COSClient(srcCredentials, new ClientConfig(srcBucketRegion));
CopyObjectRequest copyObjectRequest = new CopyObjectRequest(srcBucketRegion, srcBucketName,
        srcKey, destBucketName, destKey);
try {
    Copy copy = transferManager.copy(copyObjectRequest, srcCOSClient, null);
    // Returns an asynchronous result "copy". You can call waitForCopyResult to wait synchronously for the replication to end. If successful, CopyResult is returned; otherwise, an exception will be thrown.
    CopyResult copyResult = copy.waitForCopyResult();
    // Get the CRC64 value of the replicated object
    String crc64Ecma = copyResult.getCrc64Ecma();
} catch (CosServiceException e) {
    e.printStackTrace();
} catch (CosClientException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
}

Parameter description

Request members:

Response

• Success: returns Copy. You can query whether the copy is completed, or wait until the copy finishes synchronously.
• Failure: An error (such as authentication failure) occurs, throwing the "CosClientException" or "CosServiceException" exception. For more information, please see Troubleshooting.

Client-Side Encryption

API description

The Java SDK allows client-side encryption that encrypts files before upload and decrypts them at the time of download. There are two types of client-side encryption: AES (symmetric) and RSA (asymmetric).
These two types are for the encryption of generated random keys. File data, however, is always encrypted symmetrically using AES256.
Client-side encryption is suitable for users who store sensitive data. As it may affect the upload speed, the SDK uses serial method for multipart upload.

Preparing for client-side encryption

The client uses AES256 internally to encrypt data. By default, earlier versions of JDK6-JDK8 do not support 256-bit encryption. If run, an exception will be reported: java.security.InvalidKeyException: Illegal key size or default parameters. We then need to supplement Oracle's JCE unrestricted permissions file and deploy it in the JRE environment. Please download the corresponding files according to the JDK version used, unzip and save them in the jre/lib/security directory under JAVA_HOME.

1. JDK6 JCE supplement package
2. JDK7 JCE supplement package
3. JDK8 JCE supplement package

Encryption for upload

1. Before each upload, COS randomly generates a symmetric key which is encrypted through the customer-provided symmetric or asymmetric key. The encryption result is then Base64-encoded and stored in object metadata.
2. During the upload, the file is encrypted in memory using the AES256 algorithm.

Decryption for download

1. Get the necessary encryption information from the metadata of the file, Base64-decode it, and then decrypt it using the customer managed key (CMK) to get the encryption key at upload.
2. Use the resulting key to decrypt the downloaded input stream using AES256.

Sample request

Sample 1: Use symmetric AES256 encryption to generate a random key each time. For the complete sample code, see [Complete Example of Client Symmetric Key Encryption](https://github.com/tencentyun/cos-java-sdk-v5 /blob/master/src/main/java/com/qcloud/cos/demo/SymmetricKeyEncryptionClientDemo.java).

// Initialize user authentication information (secretId and secretKey).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// Set the COS region. For regions and their abbreviations, please see https://intl.cloud.tencent.com/zh/document/product/436/6224
ClientConfig clientConfig = new ClientConfig(new Region("COS_REGION"));

// Generate a symmetric key to save as file metadata.
KeyGenerator symKeyGenerator = KeyGenerator.getInstance("AES");
symKeyGenerator.init(256);
SecretKey symKey = symKeyGenerator.generateKey();

EncryptionMaterials encryptionMaterials = new EncryptionMaterials(symKey);
// Use AES/GCM mode and store the encrypted information in the file metadata.
CryptoConfiguration cryptoConf = new CryptoConfiguration(CryptoMode.AuthenticatedEncryption)
        .withStorageMode(CryptoStorageMode.ObjectMetadata);

// Generate an encryption client (EncryptionClient), more specifically, COSEncryptionClient. It is a subclass of COSClient, and allows for the use of all APIs supported by COSClient.
// COSEncryptionClient overwrites the COSClient for upload and download logic, and additionally performs encryption. The other operations, however, use the same logic as that of the COSClient.
COSEncryptionClient cosEncryptionClient =
        new COSEncryptionClient(new COSStaticCredentialsProvider(cred),
                new StaticEncryptionMaterialsProvider(encryptionMaterials), clientConfig,
                cryptoConf);

// Upload the file.
// Here is an example of PUT Object. For the advanced upload API, all you need to do is pass in the COSEncryptionClient object when generating TransferManager.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
File localFile = new File(localFilePath);
PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, key, localFile);
cosEncryptionClient.putObject(putObjectRequest);
cosEncryptionClient.shutdown();

Sample 2: Use asymmetric RSA encryption to generate a random key each time. For the complete sample code, see [Complete Example of Client Symmetric Key Encryption](https://github.com/tencentyun/cos-java-sdk-v5 /blob/master/src/main/java/com/qcloud/cos/demo/SymmetricKeyEncryptionClientDemo.java).

// Initialize user authentication information (secretId and secretKey).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// Set the COS region. For regions and their abbreviations, please see https://intl.cloud.tencent.com/zh/document/product/436/6224
ClientConfig clientConfig = new ClientConfig(new Region("COS_REGION"));

// Generate an asymmetric key.
KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance("RSA");
SecureRandom srand = new SecureRandom();
keyGenerator.initialize(1024, srand);
KeyPair asymKeyPair = keyGenerator.generateKeyPair();

EncryptionMaterials encryptionMaterials = new EncryptionMaterials(asymKeyPair);
// Use AES/GCM mode and store the encrypted information in the file metadata.
CryptoConfiguration cryptoConf = new CryptoConfiguration(CryptoMode.AuthenticatedEncryption)
        .withStorageMode(CryptoStorageMode.ObjectMetadata);

// Generate an encryption client (EncryptionClient), more specifically COSEncryptionClient. It is a subclass of COSClient, and allows for the use of all APIs supported by COSClient.
// COSEncryptionClient overwrites the COSClient for upload and download logic, and additionally performs encryption. The other operations, however, use the same logic as that of the COSClient.
COSEncryptionClient cosEncryptionClient =
        new COSEncryptionClient(new COSStaticCredentialsProvider(cred),
                new StaticEncryptionMaterialsProvider(encryptionMaterials), clientConfig,
                cryptoConf);

// Upload the file.
// Here is an example of putObject. For advanced API upload, use the COSEncryptionClient object when generating TransferManager.
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
File localFile = new File(localFilePath);
PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, key, localFile);
cosEncryptionClient.putObject(putObjectRequest);
cosEncryptionClient.shutdown();