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Last updated: 2025-11-13 16:25:20
FAQs
Last updated: 2025-11-13 16:25:20
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What should I do if the client network is normal but the access to COS over HTTP is very slow or the error message "Connection reset" is reported?

In some regions, ISPs may hijack COS endpoints. Therefore, we recommend you access COS over HTTPS.

What should I do if java.lang.NoSuchMethodError is reported when I run the SDK?

This is usually caused by a JAR package conflict. For example, if the JAR package the SDK depends on uses method A, but the JAR package in the HttpClient library of your project does not have method A, then the HttpClient library will be loaded in the runtime loading order, reporting NoSuchMethodError. Solutions: Solution 1: Change the version of the package in your project that has caused NoSuchMethodError to the version of the corresponding library in pom.xml in the SDK. Solution 2: Replace cos-java-sdk with cos_api-bundle. In this case, all dependencies of cos-java-sdk are installed independently, so more space will be used.
<groupId>com.qcloud</groupId>
       <artifactId>cos_api-bundle</artifactId>
<version>5.6.35</version>

What is the default timeout period of the Java SDK?

Both the default connection and read/write timeout periods of the Java SDK are 30,000 ms. You can use the SetConnectionTimeoutMs and setSocketTimeout methods in the SDK to adjust them respectively.

What should I do if the upload with the Java SDK is slow and IOException is frequently printed in the log?

Troubleshoot the problem as follows:
1. Check whether you are accessing COS over the public network. Currently, CVM instances in the same region as COS can access COS over the private network (the IP ranges resolved by the private endpoint are 10, 100, and 169). For more information on COS endpoints, see Regions and Access Endpoints. If the public network is used, check whether the egress bandwidth is too small or whether bandwidth resources are occupied by other programs.
2. Make sure that the logs in the production environment are not set to the DEBUG level. The INFO level is recommended.
3. Currently, the simple upload speed is up to 10 MB/s, and the speed of 32 concurrent uploads with advanced APIs can reach 60 MB/s. If the speed is far lower than these two values, see 1 and 2 above.
4. If IOException is printed in WARN logs, it can be ignored, and the SDK will retry. IOException may be caused by a slow network connection. For solutions, see 1 and 2 above.

What should I do if there is a plus sign (+) in the requested upload path, reporting "Code: 403 SignatureDoesNotMatch"?

Possible cause: The version of HttpClient in the Java environment leads to an URL-encoding error. You can troubleshoot in either of the following ways: Solution 1: Use HttpClient 4.5.3.
<groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
 <version>4.5.3</version>
Solution 2: Replace cos-java-sdk with cos_api-bundle. In this case, all dependencies of cos-java-sdk are installed independently, so more space will be used.
<groupId>com.qcloud</groupId>
       <artifactId>cos_api-bundle</artifactId>
<version>5.6.35</version>

What should I do if the Java SDK reports an error indicating that a certain dependency version is too earlier?

Cause: The dependency version of your Java environment conflicts with that required by the Java SDK. Solutions: Solution 1: Upgrade the dependency to the required version as prompted. Solution 2: Replace cos-java-sdk with cos_api-bundle. In this case, all dependencies of cos-java-sdk are installed independently, so more space will be used.
<groupId>com.qcloud</groupId>
       <artifactId>cos_api-bundle</artifactId>
<version>5.6.35</version>

How do I create a directory in the SDK?

In COS, both files and directories are objects, where directories are objects that end with /. When creating a file, you don't need to create a directory. For example, when you create a file with the object key xxx/yyy/zzz.txt, set the key to xxx/yyy/zzz.txt instead of creating the object xxx/yyy/. Directories are separated by / to show the hierarchy when displayed in the console. To create a directory object, use the following sample code:
String bucketName = "examplebucket-1250000000";
String key = "folder/images/";
// A directory object is an empty file that ends with `/`, where a byte stream with a length of 0 is uploaded.
InputStream input = new ByteArrayInputStream(new byte[0]);
ObjectMetadata objectMetadata = new ObjectMetadata();
objectMetadata.setContentLength(0);

PutObjectRequest putObjectRequest =
new PutObjectRequest(bucketName, key, input, objectMetadata);
PutObjectResult putObjectResult = cosClient.putObject(putObjectRequest);

How do I use HTTPS in the SDK?

In the SDK, relevant configuration items are put in the ClientConfig class. Below is the sample code:
// Initialize the user authentication information (`secretId` and `secretKey`).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// Set the bucket region. For the abbreviations for COS regions, visit https://www.tencentcloud.com/document/product/436/6224.
ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));
// Configure HTTPS.
clientConfig.setHttpProtocol(HttpProtocol.https);
// Generate a COS client.
COSClient cosClient = new COSClient(cred, clientConfig);

How do I use a proxy in the SDK?

If you need to use a proxy to access COS, you can configure a proxy IP (or domain name) and port in the ClientConfig class. Below is the sample code:
// Initialize the user authentication information (`secretId` and `secretKey`).
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// Set the bucket region. For the abbreviations for COS regions, visit https://www.tencentcloud.com/document/product/436/6224.
ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));
// Configure a proxy (both the IP and port need to be set).
// Set the proxy IP (or pass in a domain name).
clientConfig.setHttpProxyIp("192.168.2.3");
// Set the proxy port.
clientConfig.setHttpProxyPort(8080);
// Generate a COS client.
COSClient cosClient = new COSClient(cred, clientConfig);

How do I customize EndpointBuilder?

In scenarios where the endpoint needs to be specified for an API request, you need to implement the buildGeneralApiEndpoint and buildGetServiceApiEndpoint functions in the EndpointBuilder API to specify the remote endpoints for general API requests and GETService requests respectively. Below is the sample code:
// Step 1. Implement the two functions in the `EndpointBuilder` API.
class SelfDefinedEndpointBuilder implements EndpointBuilder {
    @Override
    public String buildGeneralApiEndpoint(String bucketName) {
        return String.format("%s.%s", bucketName, "mytest.com");
    }

    @Override
    public String buildGetServiceApiEndpoint() {
        return "service.mytest.com";
    }
}

// Step 2. Initialize the client.
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
SelfDefinedEndpointBuilder selfDefinedEndpointBuilder = new SelfDefinedEndpointBuilder();
ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing"));
clientConfig .setEndpointBuilder(selfDefinedEndpointBuilder);
COSClient cosClient = new COSClient(cred, clientConfig);

Do I need to add the / prefix to key values used in SDK operations such as upload, download, and batch deletion?

The key value does not need to be prefixed with / for COS objects. For example, if you set the key value of a COS object to exampleobject, you can access it at the http://cos.ap-guangzhou.myqcloud.com/exampleobject URL.
Note:
Do not pass in a key prefixed with / in a batch deletion request; otherwise, object deletion will fail.
COS Java SDK on an earlier version supports only APPID values starting with 125. If you are using an APPID starting with 130, we recommend you update the SDK to the latest version. For more information on how to download and install the Java SDK, see Getting Started.

What should I do if the COS Java SDK reports an error when I upload large files?

To upload files larger than 5 GB by using the Java SDK, we recommend you use the advanced upload API. It automatically determines whether to use simple or multipart upload based on the length and data type of your file.

How do I get the file upload progress in the Java SDK?

To get the file upload progress, we recommend you use the advanced upload API. You can use the getProgress() method of Upload to get the TransferProgress class.

Does Java SDK support calculating the CRC64 checksum of a local file?

No. You need to implement this feature on your business side. For more information, see Java issues.

How is the 21-bit CRC64 checksum returned by COS compared with the locally calculated CRC64 checksum?

The Long of Java supports only 20 digits. You can compare as follows:
CRC64 localCRC = new CRC64();
// Calculate the local CRC64 value.
localCRC.update();
//...

// Convert the CRC64 returned by COS into Long:
cosCRC = crc64ToLong(strCOSCRC);

// Perform comparison.
if (cosCRC == localCRC.getValue()) {
   xxx
}

// Convert the CRC64 returned by COS into a Long in Java.
long crc64ToLong(String crc64) {
   if (crc64.charAt(0) == '-') {
       return negativeCrc64ToLong(crc64);
   } else {
       return positiveCrc64ToLong(crc64);
   }
}

long positiveCrc64ToLong(String strCrc64) {
   BigInteger crc64 = new BigInteger(strCrc64);
   BigInteger maxLong = new BigInteger(Long.toString(Long.MAX_VALUE));

   int maxCnt = 0;

   while (crc64.compareTo(maxLong) > 0) {
       crc64 = crc64.subtract(maxLong);
       maxCnt++;
   }

   return crc64.longValue() + Long.MAX_VALUE * maxCnt;
}

long negativeCrc64ToLong(String strCrc64) {
   BigInteger crc64 = new BigInteger(strCrc64);
   BigInteger minLong = new BigInteger(Long.toString(Long.MIN_VALUE));

   int minCnt = 0;

   while (crc64.compareTo(minLong) < 0) {
       crc64 = crc64.subtract(minLong);
       minCnt++;
   }

   return crc64.longValue() + Long.MIN_VALUE * minCnt;
}

Can Java SDK use persistent connections?

Java SDK uses persistent connections by default.

How do I use the Java SDK to get all the paths to the specified directory and determine whether the paths are files or folders?

You can use the feature of object list querying as described in Getting Started in the Java SDK to list all objects in a bucket. You can use the prefix parameter to specify the directory prefix.

What should I do if the Java SDK reports the error "java.lang.IllegalStateException: Connection pool shut down"?

1. COSClient is a thread-safe class that allows multi-thread access to the same instance. Because an instance maintains a connection pool internally, creating multiple instances may lead to resource exhaustion. Make sure that there is only one instance in the program lifecycle, and call the COSClient.shutdown() method to shut down the instance when it is no longer needed. If you need to create a new instance, shut down the previous one first. We recommend you use only one COSClient in a thread and call COSClient.shutdown() after all programs end and exit.
2. COSClient is also used in the TransferManager encapsulation class of advanced APIs. We recommend you call TransferManager.shutdownNow(false) after all programs end and exit. In addition, if another COSClient is reused when a TransferManager instance is created, add the parameter false (i.e., TransferManager.shutdownNow(false)) when closing the instance. This avoids closing the reused COSClients and thus causing errors in other places where it is used.

What should I do if the Java SDK reports the error "com.qcloud.cos.exception.CosServiceException: Request has expired (Status Code: 403; Error Code: AccessDenied)"?

If the error is caused by the expiration of the signature, simply generate a new signature. If the error persists, check whether the local time of the server is the same as the time in the current time zone.
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