Help & DocumentationCloud Object StorageSDK DocumentationJava SDKActions on Objects

Actions on Objects

Last updated: 2020-03-17 11:48:05

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Contents：

Introduction

This document provides an overview of APIs and SDK sample codes related to simple operations, multipart operations and other operations on objects.

Simple Operations

API Operation Description
GET Bucket（List Object） Querying object list Queries a part of or all objects in a bucket
PUT Object Simply uploading an object Uploads an object to a bucket
HEAD Object Gets object metadata Gets the meta information of an object
GET Object Gets an object Downloads an object (file) locally
PUT Object - Copy Sets object replication Copies a file to the destination path
DELETE Object Deletes a single object Deletes the specified object in the bucket
DELETE Multiple Objects Deleting multiple objects Deletes multiple objects from a bucket in a single request

Multipart Upload Operations

API Operation Description
List Multipart Uploads Querying a multipart upload Queries the information of a multipart upload in progress
Initiate Multipart Upload Initializes multipart upload Initializes a multipart upload operation
Upload Part Uploading parts Uploads file parts
Upload Part - Copy Copying a part Copies an object as a part
List Parts Querying uploaded parts Queries uploaded parts in the specified multipart upload operation
Complete Multipart Upload Completing a multipart upload Completes the multipart upload of the entire file
Abort Multipart Upload Aborting a multipart upload Aborts a multipart upload operation and deletes the uploaded parts

Other Operations

API Operation Description
POST Object restore Restoring an archived object Restores an archived object for access
PUT Object acl Setting object ACL Sets the ACL for the specified object in a bucket
GET Object acl Querying object ACL Queries the ACL of an object

Simple Operations

Querying the object list

Feature

This API (GET Bucket (List Object)) is used to query some or all objects in a bucket.

Method Prototype

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

Parameter Description

Parameter Name Description Type
listObjectsRequest Request for obtaining a file list ListObjectsRequest

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
prefix Constructor or set method Limiting the returned result objects, prefixed with prefix. By default, there is no limit, and the default value for all Bucket members
is empty: ""		 String
marker Constructor or set method Marking the starting position of the list, which can be set to empty for the first time, and subsequent requests need to be set to the nextMarker in the previous returned listObjects value String
delimiter Constructor or set method Delimiter. It indicates that the path that starts with "prefix" and ends with delimiter for the first time will be returned. String
maxKeys Constructor or set method The maximum number of returned members (less than 1,000). Default: 1,000 Integer

Returned Result

  • Successful: Returns ObjectListing type, including all members and nextMarker.
  • Failure: Throws CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// Enter the bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
ListObjectsRequest listObjectsRequest = new ListObjectsRequest();
// Setting bucket name
listObjectsRequest.setBucketName(bucket);
// The prefix indicates the key of the listed objects started with the prefix
listObjectsRequest.setPrefix("");
// The delimiter indicates the separator. Set "/" to list objects in the current directory; set to null to list all objects.
listObjectsRequest.setDelimiter("/");
// Setting the maximum number of traversed objects (up to 1000 for one listobject)
listObjectsRequest.setMaxKeys(1000);
ObjectListing objectListing = null;
do {
    try{
        ObjectListing objectListing = cosClient.listObjects(listObjectsRequest);
    } catch (CosXmlServiceException e) {
        e.printStackTrace();
        return;
    } catch (CosXmlClientException e) {
        e.printStackTrace();
        return;
    }
    // The common prefix indicates the path truncated by delimiter. If the delimiter is set to "/", the common prefix indicates the paths of all subdirectories
    List<String> commonPrefixs = objectListing.getCommonPrefixes();

    // The object summary indicates a list of all listed objects
    for (COSObjectSummary cosObjectSummary : objectListing.getObjectSummaries()) {
    for (COSObjectSummary cosObjectSummary : objectListing.getObjectSummaries()) {
        // File path key
        String key = cosObjectSummary.getKey();
        // File etag
        String etag = cosObjectSummary.getETag();
        // File length
        long fileSize = cosObjectSummary.getSize();
        // File storage type
        String storageClass = cosObjectSummary.getStorageClass();
    }

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

Uploading an object using simple upload

Feature

This API (Put Object) is used to upload objects to the specified bucket. Uploading a local file or an input stream of known length to COS. It is suitable for uploading small image files (below 20MB), a maximum of 5GB (inclusive) is supported, please use Multipart Upload 9C) or Advanced API to upload if more than 5GB.

  • The file length and MD5 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.
    The number of access policies is up to 1000. Do not set object ACL control if it is not required. The object inherits the bucket permissions by default.
  • After upload, you can use the same key to call the GetObject API to download the file locally, or you can generate a pre-signed URL (please specify the download method as GET, see specific API description below), and send it to other paths for download.

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;

Parameter Description

Parameter Name Description Type
putObjectRequest File upload request PutObjectRequest

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key Constructor or set method The key is the unique identifier of the object in the bucket.
For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the object key is doc/picture.jpg, see Object Key		 String
file Constructor or set method Local File File
input Constructor or set method Input Stream InputStream
metadata Constructor or set method Meta information of a file ObjectMetadata

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

Parameter Name Description Type
httpExpiresDate Cache timeout, which is the value of the Expires field in the HTTP response header Date
ongoingRestore Restoring this object from archive storage type Boolean
userMetadata User-defined meta information prefixed with x-cos-meta- Map <String, String>
metadata Headers other than user-defined meta information Map<String, String>

Returned Result

  • Successful: PutObjectResult, including the file ETag and other information.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Response Parameters

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

Parameter Name Description Type
requestId Request ID String
dateStr Current server time String
versionId Enabling a versioned bucket and version ID of the object is returned String
eTag MD5 value of the object returned by simple upload API String

Request Samples

// 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 a input stream must be known in advance. Otherwise, it may cause oom)
FileInputStream fileInputStream = new FileInputStream(localFile);
ObjectMetadata objectMetadata = new ObjectMetadata();
// Setting the length of an input stream to 500
objectMetadata.setContentLength(500);
// Setting Content type. Default is application/octet-stream
objectMetadata.setContentType("application/pdf");
putObjectResult = cosClient.putObject(bucketName, key, fileInputStream, objectMetadata);
etag = putObjectResult.getETag();
// Closing the input stream...

// Method 3: Provide more fine-grained control. Common settings are as follows
// 1 Storage-class. Enumerated values：Standard, Standard_IA, Archive. Default value: Standard
// 2. Content-type. For local file upload, the files are mapped based on the suffix by default. For example, the jpg file is mapped as image/jpeg
// For input stream upload, the default is application/octet-stream
// 3. Set permissions when uploading (or by calling API set object acl)
// 4 To disable MD5 upload verification globally, set the system environment variable. This will affect all upload verification. Verification is 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);
// Setting the storage type to low frequency
putObjectRequest.setStorageClass(StorageClass.Standard_IA);
// Setting custom attributes (such as content-type, content-disposition)
ObjectMetadata objectMetadata = new ObjectMetadata();
// Setting Content type. Default is application/octet-stream
objectMetadata.setContentType("image/jpeg");
putObjectRequest.setMetadata(objectMetadata);
PutObjectResult putObjectResult = cosClient.putObject(putObjectRequest);
String etag = putObjectResult.getETag();  // Obtain the file etag

Querying object metadata

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key The key is the unique identifier of the object in the bucket. For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String

Returned Result

  • Successful: No value is returned.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

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

Downloading an object

Feature

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

Method Prototype

// Method 1: Download the 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;

Parameter Description

Parameter Name Description Type
getObjectRequest File download request GetObjectRequest
destinationFile Locally saved file File

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key Constructor or set method The key is the unique identifier of the object in the bucket.
For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the object key is doc/picture.jpg, see Object Key		 String
range Set Method Download range Long[]

Returned Result

  • Method 1 (Get the input stream of the downloaded file)
    • Successful: Returns COSObject type, including the input stream and file attributes.
    • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.
  • Method 1 (Download the file locally)
    • Successful: Returns the file attribute objectMetadata, including the file's custom header, content-type and other attributes.
    • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// 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);
COSObject cosObject = cosClient.getObject(getObjectRequest);
COSObjectInputStream cosObjectInput = cosObject.getObjectContent();

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

Setting object replication

Feature

This API (Put Object Copy) is used to copy one object to another. It supports cross-region, cross-account, and cross-bucket copying. You need to have read permission to the source file and write permission to the destination file. File copy supports a maximum of 5G, please use advanced API to copy files greater than 5G.

Method Prototype

public CopyObjectResult copyObject(CopyObjectRequest copyObjectRequest)
            throws CosClientException, CosServiceException

Parameter Description

Parameter Name Description Type
copyObjectRequest File copy request CopyObjectRequest

Request member description:

Parameter Name Description Type
sourceBucketRegion Region of the source Bucket. Default: same with the region of the current clientconfig, which represents an intra-region copy String
sourceBucketName Source bucket name, naming format is BucketName-APPID. For details, see Object Overview String
key Source Key. The key is the unique identifier of the object in the bucket. For example, in the object's access domain examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
sourceVersionId Version ID of the source file with multiple versions. Default: The latest version of the source file String
destinationBucketName Name of destination Bucket. The bucket should be named in a format of {name}-{appid}, where name should be comprised of letters, numbers, and dashes. String
key Destination key. The key is the unique identifier of the object in the bucket. For example, in the object's access domain examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
StorageClass Sets file storage type: STANDARD and STANDARD_IA. Default: STANDARD string

Returned Result

  • Successful: Returns CopyObjectResult, including Etag and other information of the new file.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// Copying the same account in the same 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 bucket name in the format of BucketName-APPID.
String bucketName = "examplebucket-1250000000";
// The destination file to be copied
String key = "exampleobject";
CopyObjectRequest copyObjectRequest = new CopyObjectRequest(srcBucketName, srcKey, destBucketName, destKey);
CopyObjectResult copyObjectResult = cosClient.copyObject(copyObjectRequest);

// Cross-account and cross-region copy (The read permission to source file and the write permission to 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);

Deleting a single object

Feature

This API (Delete Object) is used to delete the specified object.

Method Prototype

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

Parameter Description

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key The key is the unique identifier of the object in the bucket. For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String

Returned Result

  • Successful: No value is returned.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

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

Deleting multiple objects

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Description Type
deleteObjectsRequest Request DeleteObjectsRequest

Request member description:

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
Quiet Indicating the method by which the result is returned for the deletion. Available values: true and false. Defaults to false. If it is set to true, only error message for failed deletion is returned. If it is set to false, messages indicating successful and failed deletion are returned. bool
keys list of object paths, version number of the object is optional List<DeleteObjectsRequest.KeyVersion>

DeleteObjectsRequest.KeyVersion members are described as follows:

Parameter Name Description Type
key The key is the unique identifier of the object in the bucket. For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
version When enabling bucket versioning, specify the version number of the deleted object, optional String

Returned Result

  • Successful: No value is returned.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

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

DeleteObjectsRequest deleteObjectsRequest = new DeleteObjectsRequest(bucketName);
// Setting 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>();
// Entering 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);

// Deleting files in batches
try{
    DeleteObjectsResult deleteObjectsResult = cosClient.deleteObjects(deleteObjectsRequest);
    List<DeleteObjectsResult.DeletedObject> deleteObjectResultArray = deleteObjectsResult.getDeletedObjects();
} catch (MultiObjectDeleteException mde) { // If part of deletion succeeds and other fails, MultiObjectDeleteException is returned
    List<DeleteObjectsResult.DeletedObject> deleteObjects = mde.getDeletedObjects();
    List<MultiObjectDeleteException.DeleteError> deleteErrors = mde.getErrors();
} catch (CosServiceException e) { // For other errors such as parameter error, identity authentication will not throw CosServiceException
    e.printStackTrace();
    throw e;
} catch (CosClientException e) { // For client error, such as COS connection fails
    e.printStackTrace();
    throw e;
}

Multipart Operations

Querying multipart upload

Feature

This API (List Multipart Uploads) is used to query in-progress multipart uploads in the specified bucket.

Method Prototype

public MultipartUploadListing listMultipartUploads(
            ListMultipartUploadsRequest listMultipartUploadsRequest)
            throws CosClientException, CosServiceException

Parameter Description

Parameter Name Description Type
listMultipartUploadsRequest Request ListMultipartUploadsRequest

Request member description:

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
- KeyMarker The key value where the entry list starts String
delimiter Delimiter is a sign. If Prefix exists, the same paths between Prefix and delimiter are grouped as the same type and defined as Common Prefix, and then all Common Prefixes are listed. If Prefix does not exist, the listing process starts from the beginning of the path NSString *
prefix The returned Object key must be prefixed with Prefix. Note that the returned key will still contain Prefix when querying with prefix. NSString
- UploadIdMarker The UploadId value where the entry list starts String
maxUploads Sets the maximum number of multipart returned. Valid values: 1-1000 int
EncodingType Specifies the encoding type of the returned values; valid value: url String

Returned Result

  • Successful: Returns MultipartUploadListing, which contains information that multipart upload is in progress.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// 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);

Uploading object via multipart upload

This includes the following operations:

  • Multipart upload objects: Initializing multipart upload, uploading parts, and completing all multipart uploads
  • Resuming the multipart upload: Querying the parts uploaded, uploading parts, and completing all multipart uploads

    Terminating multipart upload

Initializing multipart upload

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Description Type
initiateMultipartUploadRequest Request InitiateMultipartUploadRequest

Request member description:

Parameter Name Setting Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key Constructor or set method Stored on COS object’s Object Key String

Returned Result

  • Successful: Returns InitiateMultipartUploadResult type, including the upload ID required for subsequent multipart upload.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// 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();

Uploading Parts

This API (Upload Part) is used to upload a part.

Method Prototype

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

Parameter Description

Parameter Name Description Type
uploadPartRequest Request UploadPartRequest

Request member description:

Parameter Name Setting Method Description Type
bucketName Set Method Bucket naming format is BucketName-APPID. For details, see Object Overview String
key Set Method Stored on COS object’s Object Key String
uploadId Set Method Identifies the uploadId of the specified multipart upload string
partNumber Set Method Identifies the number of the specified part, which should be ≥ 1. int
inputStream Set Method Input stream to be uploaded in multipart InputStream

Returned Result

  • Successful: Returns UploadPartResult, which contains the eTag information of the uploaded parts.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// Uploading up to 10,000 parts, supported size is 1M-5G.
// Setting the size of each part to 4 MB. If there are a total of n parts, the size of part 1 to part n-1 is the same, and the last part is less than or equal to the size of previous parts.
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's data. The length of input stream is partSize.
UploadPartRequest uploadRequest = new UploadPartRequest().withBucketName(bucketName).
        withUploadId(uploadId).withKey(key).withPartNumber(partNumber).
        withInputStream(partStream).withPartSize(partSize);
UploadPartResult uploadPartResult = cosClient.uploadPart(uploadRequest);
String eTag = uploadPartResult.getETag();  // Obtain the Etag of the part
partETags.add(new PartETag(partNumber, eTag));  // partETags records Etag information of all uploaded parts
// ... Uploading parts with the partNumber of 2 to n

Copying Parts

Feature

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

Method Prototype

public CopyPartResult copyPart(CopyPartRequest copyPartRequest) throws CosClientException, CosServiceException

Parameter Description

Parameter Name Description Type
copyPartRequest Request CopyPartRequest

Request member description:

Parameter Name Setting Method Description Type
destinationBucketName Set Method Destination bucket name, Bucket naming format is BucketName-APPID. For details, see Object Overview String
destinationKey Set Method Destination object name, stored on COS object’s Object Key String
uploadId Set Method Identifies the uploadId of the specified multipart upload String
partNumber Set Method Identifies the number of the specified multipart, must be>=1 int
sourceBucketRegion Set Method Source bucket region Region
sourceBucketName Set Method Source bucket name String
sourceKey Set Method Source object name, stored on COS object’s Object Key String
firstByte Set Method First byte offset of the source object Long
lastByte Set Method Last byte offset of the source object Long

Returned Result

  • Successful: CopyPartResult is returned, including the ETag information of the part.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// Bucket name. Format: BucketName-APPID
// Setting destination bucket name, object name and multipart upload ID
String bucketName = "examplebucket-1250000000";
String destinationTargetKey = "exampleobject";
int partNumber = 1;
CopyPartRequest copyPartRequest = new CopyPartRequest();
copyPartRequest.setDestinationBucketName(destinationBucketName);
copyPartRequest.setDestinationKey(destinationTargetKey);
copyPartRequest.setUploadId(uploadId);
copyPartRequest.setPartNumber(partNumber);
// Setting 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());

Querying uploaded parts

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Setting Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key Constructor or set method Object Name String
uploadId Constructor or set method UploadId of the multipart upload to be queried String
MaxParts Maximum number of entries returned at a time. Default value: 1,000 String No
PartNumberMarker By default, entries are listed in UTF-8 binary order starting from the marker String
- Encoding-type Specifies the encoding type of the returned value String

Returned Result

  • Successful: Returns PartListing, including the ETag and No. of each part as well as the starting marker of the next list.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// ListPart is used to obtain the information of the uploaded part based on uploadId before the multipart upload is completed or aborted. It can be used 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());

Completing multipart upload

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Setting Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Bucket Overview String
key Constructor or set method Stored on COS object’s Object Key String
uploadId Constructor or set method Identifies the specified uploadId for multipart upload string
partETags Constructor or set method Identifies the number of the parts and the eTag returned by the upload List<PartETag>

Returned Result

  • Successful: Returns CompleteMultipartUploadResult, including the Etag of the entire file.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

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

Terminating multipart upload

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Setting Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Object Overview String
key Constructor or set method Stored on COS object’s Object Key String
uploadId Constructor or set method Identifies the specified uploadId for multipart upload string

Returned Result

  • Successful: No value is returned.
  • Failure: An error occurs (such as authentication failure), with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// 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);

Other Operations

Restoring an archived object

Feature

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

Method Prototype

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

Parameter Description

Parameter Name Description Type
restoreObjectRequest Request Type RestoreObjectRequest

Request member description:

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Object Overview String
key The key is the unique identifier of the object in the bucket. For example, in the object's access examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
expirationInDays Expired days of restored temporary files int
casJobParameters Describes the configuration information of restored type, call the setTier API to set to one of the three restore types: Tier.Standard、Tier.Expedited、Tier.Bulk CASJobParameters

Returned Result

  • Successful: No value is returned.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

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

// Setting the expiration days of temporary copies obtained by configuring restore to 1 day
RestoreObjectRequest restoreObjectRequest = new RestoreObjectRequest(bucketName, key, 1);
// Setting the restore mode to Standard. Other available modes include Expedited and Bulk. The three restore modes have different cost and speed.
CASJobParameters casJobParameters = new CASJobParameters();
casJobParameters.setTier(Tier.Standard);
restoreObjectRequest.setCASJobParameters(casJobParameters);
cosClient.restoreObject(restoreObjectRequest);

Setting object ACL

Feature

This API is used to set the ACL for the specified object in a bucket.

The number of access policies is up to 1000. Do not set object ACL control if it is not required. The object inherits the bucket permissions by default.

ACL includes a predefined permission policy (CannedAccessControlList) or a custom permission control (AccessControlList). If both of them are set, the predefined policy will be ignored and the custom policy prevails. For more information on permissions, please see the permission section.

Method Prototype

// Method 1 (Set custom policy)
public void setObjectAcl(String bucketName, String key, AccessControlList acl)
       throws CosClientException, CosServiceException
// Method 2 (Set predefined policy)
public void setObjectAcl(String bucketName, String key, CannedAccessControlList acl)
       throws CosClientException, CosServiceException
// Method 3 (Encapsulation of the two methods above, including setting of these two policies. If both of them are set, the custom policy prevails.)
public void setObjectAcl(SetObjectAclRequest setObjectAclRequest)
  throws CosClientException, CosServiceException;

Parameter Description

  • The parameters in method 3, which cover those in method 1 and 2, are used in this example.
Parameter Name Description Type
SetObjectAclRequest Class for requesting permission configuration setObjectAclRequest

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Object Overview String
key Constructor or set method The key is the unique identifier of the object in the bucket.
For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the object key is doc/picture.jpg, see Object Key		 String
acl Constructor or set method Custom permission policy AccessControlList
cannedAcl Constructor or set method Predefined policies, such as public read, public read and write, private read CannedAccessControlList
Member Name Description Type
List<Grant> Contains information of all users to be authorized Array
owner The owner of the Object or Owner Owner class

Grant type members description：

Member Name Description Type
grantee Grantee identity information Grantee
permission Authorized permission information (such as readable, writable, readable & writable) Permission

Owner type member description:

Member Name Description Type
id Identity information of an owner String
displayname Owner's name (same as id) String

CannedAccessControlList represents a preset policy for everyone. It is an enumeration type with the following enumerated values.

Enumerated Value Description
Private Private read and write (only owner can read and write)
PublicRead Public read and private write (owner can read and write, and other users can read)
PublicReadWrite Public read and write (everyone can read and write)

Returned Result

  • Successful: No value is returned.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// The identity information in permissions has format requirements. The format for the main account and sub-account is as follows:
// Both root_uin and sub_uin below must be valid QQ numbers
// The root account qcs::cam::uin/<root_uin>:uin/<root_uin> indicates that the root_uin is granted to the root account (that is, the first and second uin are the same)
// For example, qcs::cam::uin/2779643970:uin/2779643970
// The sub-account qcs::cam::uin/<root_uin>:uin/<sub_uin> indicates that the sub_uin is granted to the root_uin.
// For example, qcs::cam::uin/2779643970:uin/2779643970 
Bucket. Format: BucketName-APPID
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
// Setting a custom ACL
AccessControlList acl = new AccessControlList();
Owner owner = new Owner();
// Setting the owner information. Owner can only be a root account.
owner.setId("qcs::cam::uin/100000000001:uin/100000000001");
acl.setOwner(owner);

// Granting the main account 73410000 read and write permissions
UinGrantee uinGrantee1 = new UinGrantee("qcs::cam::uin/2779643970:uin/2779643970");
acl.grantPermission(uinGrantee1, Permission.FullControl);
cosClient.setObjectAcl(bucketName, key, acl);

// Setting a predefined ACL
// Setting private read and write (Object integrates permissions of Bucket by default)
cosClient.setObjectAcl(bucketName, key, CannedAccessControlList.Private);
// Setting public read and private write
cosClient.setObjectAcl(bucketName, key, CannedAccessControlList.PublicRead);
// Setting public read and write
cosClient.setObjectAcl(bucketName, key, CannedAccessControlList.PublicReadWrite);

Getting the object ACL

Feature

This API (Get Object ACL) is used to get the ACL of an object.

Method Prototype

public AccessControlList getObjectAcl(String bucketName, String key)
  throws CosClientException, CosServiceException;

Parameter Description

Parameter Name Description Type
bucketName Bucket naming format is BucketName-APPID. For details, see Object Overview String
key The key is the unique identifier of the object in the bucket. For example, in the object's access examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String

Returned Result

  • Successful: Returns the ACL to which the Object resides.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

Bucket. Format: BucketName-APPID
String bucketName = "examplebucket-1250000000";
String key = "exampleobject";
AccessControlList acl = cosClient.getObjectAcl(bucketName, key);

Advanced APIs (Recommended)

The advanced API encapsulates upload and download APIs using the TransferManger type. It has a thread pool inside to accept users' upload and download requests, so users can choose to submit tasks asynchronously.

// The size of the thread pool. If client and COS network are sufficient (for example, use Tencent Cloud CVM and upload COS in the same region), we recommended you set it to 16 or 32 to fully utilize network resources.
// If public network is used for transmission and network bandwidth quality is poor, we recommended you lower this value to avoid timeout caused by slow network speed.
ExecutorService threadPool = Executors.newFixedThreadPool(32);
// Inputting a threadpool. If there is no thread pool, a single-thread pool will be generated in TransferManager by default.
transferManager = new TransferManager(cosClient, threadPool);
// Setting the threshold and size of parts for multipart upload through advanced API to 10MB
TransferManagerConfiguration transferManagerConfiguration = new TransferManagerConfiguration();
transferManagerConfiguration.setMultipartUploadThreshold(10 * 1024 * 1024);
transferManagerConfiguration.setMinimumUploadPartSize(10 * 1024 * 1024);
transferManager.setConfiguration(transferManagerConfiguration);

Closing transferManager manually after use to prevent resource leakage.

// Closing TransferManger
transferManager.shutdownNow();

Parameter Description

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

Member Name Setting Method Description Type
minimumUploadPartSize Set Method Part size for multipart upload, unit in byte, default value is 5MB long
multipartUploadThreshold Set Method If the value is greater than or equal to this value, file parts are uploaded concurrently, unit in byte, default value is 5MB long
multipartCopyThreshold Set Method If the value is greater than or equal to this value, file parts are copied concurrently, unit in byte, default value is 5M long
multipartCopyPartSize Set Method Part size for multipart copy, unit in byte, default value is 100MB long

Uploading an object

Feature

The upload API automatically selects simple upload or multipart upload based on the size of users' files, making it easy for users to use. Besides, users do not need to care about each step of the multipart upload.

Tips for other configuration attributes, storage category, MD5 verification, etc., see PUT Object API.

Method Prototype

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

Parameter Description

Parameter Name Description Type
putObjectRequest File upload request PutObjectRequest

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Object Overview String
key Constructor or set method The key is the unique identifier of the object in the bucket.
For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the object key is doc/picture.jpg, see Object Key		 String
file Constructor or set method Local File File
input Constructor or set method Input Stream InputStream
metadata Constructor or set method Meta information of a file ObjectMetadata

Return values

  • Successful: Returns Upload. You can query whether the upload is completed, or wait until the upload finishes synchronously.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// 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);
// Uploading local file
Upload upload = transferManager.upload(putObjectRequest);
// Waiting for the transfer to finish (call waitForCompletion if you want to wait for the upload to finish synchronously)
UploadResult uploadResult = upload.waitForUploadResult();

Downloading an object

Feature

This APP is used to download COS object locally.

Method Prototype

// Downloading the object
public Download download(final GetObjectRequest GetObjectRequest, final File file);

Parameter Description

Parameter Name Description Type
getObjectRequest File download request GetObjectRequest
file File to be downloaded locally File

Request member description:

Request Member Set Method Description Type
bucketName Constructor or set method Bucket naming format is BucketName-APPID. For details, see Object Overview String
key Constructor or set method The key is the unique identifier of the object in the bucket.
For example, in the object's access domain name examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the object key is doc/picture.jpg, see Object Key		 String
range Set Method Download Range Long[]

Return values

  • Successful: Returns Download. You can query whether the download is completed, or wait until the download finishes synchronously.
  • Failure: An error (such as authentication failure) occurs, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

/* 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);
# Downloading a file
Download download = transferManager.download(getObjectRequest, localDownFile);
// Waiting for the transfer to finish (call waitForCompletion if you want to wait for the upload to finish synchronously)
download.waitForCompletion();
  • Replicating objects

Feature

This API supports automatic selection of simple copy or multipart copy based on the size of the object, and the user does not need to worry about the size of the copied file.

Method Prototype

// Uploading the object
public Copy copy(final CopyObjectRequest copyObjectRequest);

Parameter Description

Parameter Name Description Type
copyObjectRequest File copy request CopyObjectRequest

Request member description:

Parameter Name Description Type
sourceBucketRegion Region of the source Bucket. Default: same with the region of the current clientconfig, which represents an intra-region copy String
Bucket Bucket name in the format of BucketName-APPID String
key Source key. The key is the unique identifier of the object in the bucket. For example, in the object's access domain examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
sourceVersionId Version ID of the source file with multiple versions. Default: The latest version of the source file String
Bucket Bucket name in the format of BucketName-APPID String
key Destination key. The key is the unique identifier of the object in the bucket. For example, in the object's access domain examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/do/picture.jpg, the object key is doc/picture.jpg. For details, see Object Overview String
StorageClass Sets file storage type: STANDARD and STANDARD_IA. Default: STANDARD string

Return values

  • Successful: 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, with a CosClientException or CosServiceException exception. For details, see Troubleshooting.

Request Samples

// The region of bucket to copy. Cross-region copy is supported.
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = 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 bucket name in the format of BucketName-APPID.  */
String bucketName = "examplebucket-1250000000";
// The destination file to be copied
String key = "exampleobject";
// Generating srcCOSClient to get source file information
COSClient srcCOSClient = new COSClient(srcCredentials, new ClientConfig(srcBucketRegion));
CopyObjectRequest copyObjectRequest = new CopyObjectRequest(srcBucketRegion, srcBucketName,
        srcKey, destBucketName, destKey);
Copy copy = transferManager.copy(copyObjectRequest, srcCOSClient, null);
// Returning an asynchronous result copy. You can synchronously call waitForCopyResult to wait for copy to end. If successful, CopyResult is returned; If failed, an exception will be thrown.
CopyResult copyResult = copy.waitForCopyResult();
srcCOSClient.shutdown();

Client Encryption

Feature

Java sdk supports client encryption, encrypting files before uploading and decrypting them when downloading. Client encryption supports symmetric AES and asymmetric RSA encryption.
The symmetry and asymmetry here are only used to encrypt the generated random keys. AES256 is always used to encrypt file data symmetrically.
Client encryption is suitable for users who store sensitive data. client encryption may sacrifice certain upload speed, and the SDK may use serial method for multipart upload.

Preparing for client encryption

Client encryption 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 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

Uploading encryption process

  1. Before uploading a file object, we randomly generate a symmetric encryption key. The random key is encrypted by the symmetric or asymmetric key provided by the user, and the encrypted result is encoded with base64 and stored in the meta information of the object.
  2. When the file object is uploaded, AES256 algorithm is used to encrypt the file object in memory.

Downloading decryption process

  1. Obtain the necessary encryption information in the meta information of the file, and decrypt the information decoded with base64 using the user key to obtain the key of the encrypted data
  2. Use the key to decrypt the downloaded input stream using AES256 to obtain the decrypted file input stream.

Request Samples

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, secretKey).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// Setting the bucket region. For the abbreviation of COS region, refer to https: //www..com/document/product/436/6224
ClientConfig clientConfig = new ClientConfig(region);

// Generating a symmetric key and you can save it in a file
KeyGenerator symKeyGenerator = KeyGenerator.getInstance("AES");
symKeyGenerator.init(256);
SecretKey symKey = symKeyGenerator.generateKey();

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

// Generating encryption client (EncryptionClient). The COSEncryptionClient is a subclass of COSClient, and all APIs supported by COSClient are also available.
// EncryptionClient overwrites the COSClient upload and download logic. It will perform the encryption operation internally. The other operations execution logic is consistent with that of the COSClient.
COSEncryptionClient cosEncryptionClient =
        new COSEncryptionClient(new COSStaticCredentialsProvider(cred),
                new StaticEncryptionMaterialsProvider(encryptionMaterials), clientConfig,
                cryptoConf);

// Uploading 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();

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, secretKey).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// COS region. For regions and their abbreviations, see https://intl.cloud.tencent.com/document/product/436/6224?from_cn_redirect=1
ClientConfig clientConfig = new ClientConfig(region);

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

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

// Generating encryption client (EncryptionClient). The COSEncryptionClient is a subclass of COSClient, and all APIs supported by COSClient are also available.
// EncryptionClient overwrites the COSClient upload and download logic. It will perform the encryption operation internally. The other operations execution logic is consistent with that of the COSClient.
COSEncryptionClient cosEncryptionClient =
        new COSEncryptionClient(new COSStaticCredentialsProvider(cred),
                new StaticEncryptionMaterialsProvider(encryptionMaterials), clientConfig,
                cryptoConf);

// Uploading 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();