String bucketName = "examplebucket-1250000000";
String key = "folder/images/";
// 目录对象即是一个/结尾的空文件，上传一个长度为 0 的 byte 流
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);

// 初始化用户身份信息(secretId, secretKey)
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// 设置 bucket 的区域, COS 地域的简称请参照 https://www.tencentcloud.com/document/product/436/6224
ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));
// 配置使用 https
clientConfig.setHttpProtocol(HttpProtocol.https);
// 生成 cos 客户端
COSClient cosClient = new COSClient(cred, clientConfig);

// 初始化用户身份信息(secretId, secretKey)
String secretId = "COS_SECRETID";
String secretKey = "COS_SECRETKEY";
COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
// 设置 bucket 的区域, COS 地域的简称请参照 https://www.tencentcloud.com/document/product/436/6224
ClientConfig clientConfig = new ClientConfig(new Region("ap-beijing-1"));
// 配置使用代理(IP 和端口需要同时设置)
// 设置代理 IP (也可传入域名)
clientConfig.setHttpProxyIp("192.168.2.3");
// 设置代理端口
clientConfig.setHttpProxyPort(8080);
// 生成 cos 客户端
COSClient cosClient = new COSClient(cred, clientConfig);

// 步骤1：实现 EndpointBuilder 接口中的两个函数
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";
    }
}

// 步骤2：初始化客户端
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);