android如何连接mysql数据库

<?php
$servername = "your_server_address";
$username = "your_username";
$password = "your_password";
$dbname = "your_database_name";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
echo "连接成功";
?>

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    URL url = new URL("http://your_server_address/db_connect.php");
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("GET");
                    BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                    String inputLine;
                    StringBuffer content = new StringBuffer();
                    while ((inputLine = in.readLine()) != null) {
                        content.append(inputLine);
                    }
                    in.close();
                    conn.disconnect();

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            // 处理返回的数据
                            Toast.makeText(MainActivity.this, content.toString(), Toast.LENGTH_LONG).show();
                        }
                    });
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}