我无法在Android Studio中使用HTTP POST将JSON发送到我的服务器

android {
    // ...

    // 添加Internet权限
    uses-permission android:name="android.permission.INTERNET"

    // ...
}

import android.os.AsyncTask;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpPostTask extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... params) {
        String urlString = params[0];
        String json = params[1];
        String result = "";

        try {
            URL url = new URL(urlString);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/json");
            connection.setDoOutput(true);

            DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
            outputStream.writeBytes(json);
            outputStream.flush();
            outputStream.close();

            int responseCode = connection.getResponseCode();

            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                StringBuilder response = new StringBuilder();

                while ((line = reader.readLine()) != null) {
                    response.append(line);
                }

                reader.close();
                result = response.toString();
            } else {
                result = "Error: " + responseCode;
            }

        } catch (Exception e) {
            e.printStackTrace();
            result = "Error: " + e.getMessage();
        }

        return result;
    }

    @Override
    protected void onPostExecute(String result) {
        // 在这里处理网络请求的结果
    }
}

String url = "https://your-server-url";
String json = "{\"key1\":\"value1\", \"key2\":\"value2\"}";

HttpPostTask task = new HttpPostTask();
task.execute(url, json);