// Create a COSClient instance, which is used to initiate requests later.
COSClient createCOSClient() {
    // Here, the temporary key information is needed.
    // For details on how to generate temporary keys, please visit https://www.tencentcloud.com/document/product/436/14048#cos-sts-sdk.
    String tmpSecretId = "TMPSECRETID";
    String tmpSecretKey = "TMPSECRETKEY";
    String sessionToken = "SESSIONTOKEN";

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

    // `ClientConfig` contains the COS client configuration for subsequent COS requests.
    ClientConfig clientConfig = new ClientConfig();

    // Set the bucket region.
    // For more information on COS regions, visit https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1.
    clientConfig.setRegion(new Region("COS_REGION"));

    // Set the request protocol to `HTTP` or `HTTPS`.
    // For v5.6.53 or earlier, HTTPS is recommended.
    // For v5.6.54 or later, HTTPS is used by default.
    clientConfig.setHttpProtocol(HttpProtocol.https);

    // The following settings are optional.

    // Set the read timeout period, which is 30s by default.
    clientConfig.setSocketTimeout(30*1000);
    // Set the connection timeout period, which is 30s by default.
    clientConfig.setConnectionTimeout(30*1000);

    // If necessary, set the HTTP proxy, IP, and port.
    clientConfig.setHttpProxyIp("httpProxyIp");
    clientConfig.setHttpProxyPort(80);

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

// Create a COSClient instance, which is used to initiate requests later.
COSClient createCOSClient() {
    // Set the user identity information.
    // Log in to the [CAM console](https://console.tencentcloud.com/cam/capi) to view and manage the `SecretId` and `SecretKey` of your project.
    SecretID: os.Getenv("SECRETID"),  // User `SecretId`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
    SecretKey: os.Getenv("SECRETKEY"),  // User `SecretKey`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
    COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);

    // `ClientConfig` contains the COS client configuration for subsequent COS requests.
    ClientConfig clientConfig = new ClientConfig();

    // Set the bucket region.
    // For more information on COS regions, visit https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1.
    clientConfig.setRegion(new Region("COS_REGION"));

    // Set the request protocol to `HTTP` or `HTTPS`.
    // For v5.6.53 or earlier, HTTPS is recommended.
    // For v5.6.54 or later, HTTPS is used by default.
    clientConfig.setHttpProtocol(HttpProtocol.https);

    // The following settings are optional.

    // Set the read timeout period, which is 30s by default.
    clientConfig.setSocketTimeout(30*1000);
    // Set the connection timeout period, which is 30s by default.
    clientConfig.setConnectionTimeout(30*1000);

    // If necessary, set the HTTP proxy, IP, and port.
    clientConfig.setHttpProxyIp("httpProxyIp");
    clientConfig.setHttpProxyPort(80);

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

public URL generatePresignedUrl(String bucketName, String key, Date expiration, HttpMethodName method, Map<String, String> headers, Map<String, String> params, Boolean signPrefixMode, Boolean signHost) throws CosClientException

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

// Enter the bucket name in the format of `BucketName-APPID`.
String bucketName = "examplebucket-1250000000";
// Object key, the unique ID of an object in a bucket. For more information, see [Object Key](https://www.tencentcloud.com/document/product/436/13324).
String key = "exampleobject";

// Set the signature expiration time (optional). If it is not set, the signature expiration time in `ClientConfig` (1 hour) is used by default.
// Set the signature to expire in half an hour.
Date expirationDate = new Date(System.currentTimeMillis() + 30 * 60 * 1000);

// Enter the parameters of the current request, which should be the same as those of the actual request. This can prevent users from tampering with the HTTP request parameters. 
Map<String, String> params = new HashMap<String, String>();
params.put("param1", "value1");

// Enter the headers of the current request, which should be the same as those of the actual request. This can prevent users from tampering with the HTTP request headers.
Map<String, String> headers = new HashMap<String, String>();
headers.put("header1", "value1");

// HTTP method of the request. PUT for an upload request, GET for a download request, and DELETE for a deletion request.
HttpMethodName method = HttpMethodName.GET;

URL url = cosClient.generatePresignedUrl(bucketName, key, expirationDate, method, headers, params);
System.out.println(url.toString());

// After confirming that the process does not use the COSClient instance anymore, close it.
cosClient.shutdown();

public URL generatePresignedUrl(GeneratePresignedUrlRequest req, boolean signHost) throws CosClientException

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

// Enter the bucket name in the format of `BucketName-APPID`.
String bucketName = "examplebucket-1250000000";
// Object key, the unique ID of an object in a bucket. For more information, see [Object Key](https://www.tencentcloud.com/document/product/436/13324).
String key = "exampleobject";

GeneratePresignedUrlRequest req =
        new GeneratePresignedUrlRequest(bucketName, key, HttpMethodName.GET);

// Set the http header returned for download.
ResponseHeaderOverrides responseHeaders = new ResponseHeaderOverrides();
String responseContentType = "image/x-icon";
String responseContentLanguage = "zh-CN";
// Set the returned header to contain filename information.
String responseContentDispositon = "filename=exampleobject";
String responseCacheControl = "no-cache";
String cacheExpireStr =
        DateUtils.formatRFC822Date(new Date(System.currentTimeMillis() + 24L * 3600L * 1000L));
responseHeaders.setContentType(responseContentType);
responseHeaders.setContentLanguage(responseContentLanguage);
responseHeaders.setContentDisposition(responseContentDispositon);
responseHeaders.setCacheControl(responseCacheControl);
responseHeaders.setExpires(cacheExpireStr);

req.setResponseHeaders(responseHeaders);

// Setting the signature expiration time (optional). If it is not configured, the signature expiration time in ClientConfig (1 hour) is used by default.
// Set the signature to expire in half an hour.
Date expirationDate = new Date(System.currentTimeMillis() + 30L * 60L * 1000L);
req.setExpiration(expirationDate);

// Parameters of the current request
req.addRequestParameter("param1", "value1");
// Enter the headers of the current request
// `host` is required.
req.putCustomRequestHeader(Headers.HOST, cosClient.getClientConfig().getEndpointBuilder().buildGeneralApiEndpoint(bucketName));
req.putCustomRequestHeader("header1", "value1");

URL url = cosClient.generatePresignedUrl(req);
System.out.println(url.toString());

// After confirming that the process does not use the COSClient instance anymore, close it.
cosClient.shutdown();

// Here, the temporary key information is needed.
// For details on how to generate temporary keys, please visit https://www.tencentcloud.com/document/product/436/14048#cos-sts-sdk.
String tmpSecretId = "TMPSECRETID";
String tmpSecretKey = "TMPSECRETKEY";
String sessionToken = "SESSIONTOKEN";

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

// Enter the bucket name in the format of `BucketName-APPID`.
String bucketName = "examplebucket-1250000000";
// Object key, the unique ID of an object in a bucket. For more information, see [Object Key](https://www.tencentcloud.com/document/product/436/13324).
String key = "exampleobject";
// If the `key` does not start with "/", you need to add "/" at the beginning; otherwise, the `resource_path` will be the `key`.
String resource_path="/" + key;

ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));

// It is used to generate a signature.
COSSigner signer = new COSSigner();
// Setting the signature expiration time (optional). If it is not configured, the signature expiration time in ClientConfig (1 hour) is used by default.
// Set the signature to expire in half an hour.
Date expirationDate = new Date(System.currentTimeMillis() + 30L * 60L * 1000L);

// Parameters of the current request
Map<String, String> params = new HashMap<String, String>();
params.put("param1", "value1");

// Enter the headers of the current request
Map<String, String> headers = new HashMap<String, String>();
// `host` is required.
headers.put(Headers.HOST, clientConfig.getEndpointBuilder().buildGeneralApiEndpoint(bucketName));
headers.put("header1", "value1");

// HTTP method of the request. PUT for an upload request, GET for a download request, and DELETE for a deletion request.
HttpMethodName method = HttpMethodName.GET;

String sign = signer.buildAuthorizationStr(method, resource_path, headers, params, cred, expirationDate, true);

// Set the user identity information.
// Log in to the [CAM console](https://console.tencentcloud.com/cam/capi) to view and manage the `SecretId` and `SecretKey` of your project.
SecretID: os.Getenv("SECRETID"),  // User `SecretId`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
SecretKey: os.Getenv("SECRETKEY"),  // User `SecretKey`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);

// Enter the bucket name in the format of `BucketName-APPID`.
String bucketName = "examplebucket-1250000000";
// Object key, the unique ID of an object in a bucket. For more information, see [Object Key](https://www.tencentcloud.com/document/product/436/13324).
String key = "exampleobject";
// If the `key` does not start with "/", you need to add "/" at the beginning; otherwise, the `resource_path` will be the `key`.
String resource_path="/" + key;

ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));

// It is used to generate a signature.
COSSigner signer = new COSSigner();
// Setting the signature expiration time (optional). If it is not configured, the signature expiration time in ClientConfig (1 hour) is used by default.
// Set the signature to expire in half an hour.
Date expirationDate = new Date(System.currentTimeMillis() + 30L * 60L * 1000L);

// Parameters of the current request
Map<String, String> params = new HashMap<String, String>();
params.put("param1", "value1");

// Enter the headers of the current request
Map<String, String> headers = new HashMap<String, String>();
// `host` is required.
headers.put(Headers.HOST, clientConfig.getEndpointBuilder().buildGeneralApiEndpoint(bucketName));
headers.put("header1", "value1");

// HTTP method of the request. PUT for an upload request, GET for a download request, and DELETE for a deletion request.
HttpMethodName method = HttpMethodName.GET;

String sign = signer.buildAuthorizationStr(method, resource_path, headers, params, cred, expirationDate, true);

public static void GenerateSimplePresignedDownloadUrl() {
        // 1. Initialize user authentication information (`secretId`, `secretKey`).
            // Log in to the [CAM console](https://console.tencentcloud.com/cam/capi) to view and manage the `SecretId` and `SecretKey` of your project.
            SecretID: os.Getenv("SECRETID"),  // User `SecretId`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
            SecretKey: os.Getenv("SECRETKEY"),  // User `SecretKey`. We recommend you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
            COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
        // 2. Set the region of the bucket.
              // COS_REGION parameter, which needs to be set to the actual region of the bucket, for example, ap-beijing. For the abbreviations for more COS regions, visit https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1.
        ClientConfig clientConfig = new ClientConfig(new Region("COS_REGION"));
        // 3. Generate a COS client
        COSClient cosclient = new COSClient(cred, clientConfig);
        // The bucket name must contain `appid`.
        String bucketName = "examplebucket-1250000000";

        String key = "exampleobject";
        GeneratePresignedUrlRequest req =
                new GeneratePresignedUrlRequest(bucketName, key, HttpMethodName.GET);
        // Set the signature expiration time (optional). If it is not set, the signature expiration time in `ClientConfig` (1 hour) is used by default.
        // Set the signature to expire in half an hour.
        Date expirationDate = new Date(System.currentTimeMillis() + 30 * 60 * 1000);
        req.setExpiration(expirationDate);

        // Parameters of the current request
        // Set the speed limit value, such as 128 KB/s.
        req.addRequestParameter("x-cos-traffic-limit", "1048576");

        // Enter the headers of the current request. `Host` is required.
        req.putCustomRequestHeader(Headers.HOST,
        cosclient.getClientConfig().getEndpointBuilder().buildGeneralApiEndpoint(bucketName));
        //req.putCustomRequestHeader("header1", "value1");

        URL url = cosclient.generatePresignedUrl(req);
        System.out.println(url.toString());

        cosclient.shutdown();
    }