public void setBucketPolicy(String bucketName, String policyText)

import com.qcloud.cos.COSClient;
import com.qcloud.cos.ClientConfig;
import com.qcloud.cos.auth.BasicCOSCredentials;
import com.qcloud.cos.auth.COSCredentials;
import com.qcloud.cos.region.Region;

public class BucketPolicyDemo {
    public static void SetBucketPolicy() {
        // 1 Initialize user identity information (Recommended to use temporary key)
        String tmpSecretId = "SECRETID";
        String tmpSecretKey = "SECRETKEY";
        String sessionToken = "TOKEN";
        BasicSessionCredentials cred = new BasicSessionCredentials(tmpSecretId, tmpSecretKey, sessionToken);
        // 2 Set the region of the bucket
        Region region = new Region("COS_REGION"); //COS_REGION parameter: Configure it to the real region of the bucket, for example ap-beijing. For more abbreviations of COS regions, please see https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1
        ClientConfig clientConfig = new ClientConfig(region);
        // 3 Generating a COS client
        COSClient cosclient = new COSClient(cred, clientConfig);
        // The bucket name must contain appid
        String bucketName = "examplebucket-1250000000";
        String bucketPolicyStr = "{" +
                "    \\"Statement\\": [" +
                "      {" +
                "        \\"Principal\\": {" +
                "          \\"qcs\\": [" +
                "            \\"qcs::cam::uin/100000000001:uin/100000000011\\"" + // Replace with the UIN of the account to be granted the permission
                "          ]" +
                "        }," +
                "        \\"Effect\\": \\"allow\\"," +
                "        \\"Action\\": [" +
                "          \\"cos:PutObject\\"" +
                "        ]," +
                "        \\"Resource\\": [" + // Change to allowed path prefixes, can be determined based on the user login status of your website to judge the specific paths that allow uploads, for example: a.jpg or a/* or * (using wildcard * poses significant security risks, please evaluate usage cautiously)
                "          \\"qcs::cos:ap-guangzhou:uid/1250000000:examplebucket-1250000000/exampleobject\\"" +
                "        ]," +
                "        \\"Condition\\": {" +
                "          \\"string_equal\\": {" +
                "            \\"cos:x-cos-mime-limit\\": \\"image/jpeg\\"" +
                "          }" +
                "        }" +
                "      }" +
                "    ]," +
                "    \\"Version\\": \\"2.0\\"" +
                "  }";

        cosclient.setBucketPolicy(bucketName, bucketPolicyStr);
        cosclient.shutdown();
    }
    public static void main(String[] args) {
        SetBucketPolicy();
    }
}

public BucketPolicy getBucketPolicy(String bucketName)

import com.qcloud.cos.COSClient;
import com.qcloud.cos.ClientConfig;
import com.qcloud.cos.auth.BasicCOSCredentials;
import com.qcloud.cos.auth.COSCredentials;
import com.qcloud.cos.region.Region;
import com.qcloud.cos.model.BucketPolicy;

public class BucketPolicyDemo {
    public static void GetBucketPolicy() {
        // 1 Initialize user identity information (Recommended to use temporary key)
        String tmpSecretId = "SECRETID";
        String tmpSecretKey = "SECRETKEY";
        String sessionToken = "TOKEN";
        BasicSessionCredentials cred = new BasicSessionCredentials(tmpSecretId, tmpSecretKey, sessionToken);
        // 2 Set the region of the bucket
        Region region = new Region("COS_REGION"); //COS_REGION parameter: Configure it to the real region of the bucket, for example ap-beijing. For more abbreviations of COS regions, please see https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1
        ClientConfig clientConfig = new ClientConfig(region);
        // 3 Generating a COS client
        COSClient cosclient = new COSClient(cred, clientConfig);
        // The bucket name must contain appid
        String bucketName = "examplebucket-1250000000";
        BucketPolicy bucketPolicy = cosclient.getBucketPolicy(bucketName);
        System.out.println(bucketPolicy.getPolicyText());
          cosclient.shutdown();
    }
    public static void main(String[] args) {
        GetBucketPolicy();
    }
}

public class BucketPolicy implements Serializable {
    private static final long serialVersionUID = 1L;
    /** The raw, policy JSON text, as returned by COS */
    private String policyText;

    /**
     * Gets the raw policy JSON text as returned by COS. If no policy has been applied to the
     * specified bucket, the policy text will be null.
     * 
     * @return The raw policy JSON text as returned by COS. If no policy has been applied to the
     *         specified bucket, this method returns null policy text.
     * 
     * @see BucketPolicy#setPolicyText(String)
     */
    public String getPolicyText() {
        return policyText;
    }

    /**
     * Sets the raw policy JSON text. A bucket will have no policy text unless the policy text is
     * explicitly provided through this method.
     *
     * @param policyText The raw policy JSON text.
     * 
     * @see BucketPolicy#getPolicyText()
     */
    public void setPolicyText(String policyText) {
        this.policyText = policyText;
    }
}

public void deleteBucketPolicy(String bucketName)

import com.qcloud.cos.COSClient;
import com.qcloud.cos.ClientConfig;
import com.qcloud.cos.auth.BasicCOSCredentials;
import com.qcloud.cos.auth.COSCredentials;
import com.qcloud.cos.region.Region;
import com.qcloud.cos.model.BucketPolicy;

public class BucketPolicyDemo {
    public static void DelBucketPolicy() {
        // 1 Initialize user identity information (Recommended to use temporary key)
        String tmpSecretId = "SECRETID";
        String tmpSecretKey = "SECRETKEY";
        String sessionToken = "TOKEN";
        BasicSessionCredentials cred = new BasicSessionCredentials(tmpSecretId, tmpSecretKey, sessionToken);
        // 2 Set the region of the bucket
        Region region = new Region("COS_REGION"); //COS_REGION parameter: Configure it to the real region of the bucket, for example ap-beijing. For more abbreviations of COS regions, please see https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1
        ClientConfig clientConfig = new ClientConfig(region);
        // 3 Generating a COS client
        COSClient cosclient = new COSClient(cred, clientConfig);
        // The bucket name must contain appid
        String bucketName = "examplebucket-1250000000";
        cosclient.deleteBucketPolicy(bucketName);
          cosclient.shutdown();
    }
    public static void main(String[] args) {
        DelBucketPolicy();
    }
}