我无法通过MySQL，PHP，Volley获得Android Studio上的球员列表，按分数降序排列

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "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);
}

// 查询语句，按分数降序排列
$sql = "SELECT player_name, score FROM players ORDER BY score DESC";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出数据
    while($row = $result->fetch_assoc()) {
        echo "Player: " . $row["player_name"]. " - Score: " . $row["score"]. "<br>";
    }
} else {
    echo "0 结果";
}
$conn->close();
?>

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    private RequestQueue requestQueue;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);
        requestQueue = Volley.newRequestQueue(this);

        String url = "http://yourserver.com/get_players.php";

        StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    textView.setText(response);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    textView.setText("Error: " + error.getMessage());
                }
            });

        requestQueue.add(stringRequest);
    }
}

<uses-permission android:name="android.permission.INTERNET"/>