Java 媒体。设置循环未连续运行

当我按下“开始服务”按钮时，即使我切换到另一个应用程序，它也会在后台播放音乐，但在1到2分钟后它会停止播放音乐，但我认为它应该可以工作，因为我将“循环”设置为true，并且如果用户退出应用程序，我也希望运行我的服务。

我的问题：为什么它在1到2分钟后停止播放音乐，它是一个后台服务，应该持续运行？

MainActivity.Java

package com.fyp.riphah.myservice;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


    private Button start,stop;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        start = (Button) findViewById(R.id.button4);
        stop = (Button) findViewById(R.id.button5);
        start.setOnClickListener( this );
        stop.setOnClickListener( this );
    }

    public void btn_Download(View view) {

        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                Log.d("MyTag","Downloading started");
                try {
                    Thread.sleep(4000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.d("MyTag",Thread.currentThread().getName());
                Log.d("MyTag","Finished");
            }
        };
Thread thread = new Thread(runnable);
thread.setName("Downloading thread");
thread.start();
//        Handler handler = new Handler(Looper.getMainLooper());
//handler.postDelayed(runnable,4000);
    }

    public void playMusic(View view) {


//        MediaPlayer mediaPlayer = MediaPlayer.create(this, Settings.System.DEFAULT_ALARM_ALERT_URI);
//mediaPlayer.setLooping(true);
//mediaPlayer.start();
    }

    @Override
    public void onClick(View v) {

        if(v == start)
        {
            startService(new Intent(this,MyService.class));
        }
else if(v == stop){
    stopService(new Intent(this,MyService.class));
        }



    }
}

package com.fyp.riphah.myservice;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.provider.Settings;

import androidx.annotation.Nullable;

import java.security.Provider;
import java.util.List;
import java.util.Map;

public class MyService extends Service {


    private  MediaPlayer mediaPlayer;
    @Override
    public void onDestroy() {
        super.onDestroy();
        mediaPlayer.stop();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        mediaPlayer = MediaPlayer.create(this, Settings.System.DEFAULT_ALARM_ALERT_URI);
        mediaPlayer.start();
        mediaPlayer.setLooping(true);
        return START_STICKY;
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

MyService.java

package com.fyp.riphah.myservice;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


    private Button start,stop;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        start = (Button) findViewById(R.id.button4);
        stop = (Button) findViewById(R.id.button5);
        start.setOnClickListener( this );
        stop.setOnClickListener( this );
    }

    public void btn_Download(View view) {

        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                Log.d("MyTag","Downloading started");
                try {
                    Thread.sleep(4000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.d("MyTag",Thread.currentThread().getName());
                Log.d("MyTag","Finished");
            }
        };
Thread thread = new Thread(runnable);
thread.setName("Downloading thread");
thread.start();
//        Handler handler = new Handler(Looper.getMainLooper());
//handler.postDelayed(runnable,4000);
    }

    public void playMusic(View view) {


//        MediaPlayer mediaPlayer = MediaPlayer.create(this, Settings.System.DEFAULT_ALARM_ALERT_URI);
//mediaPlayer.setLooping(true);
//mediaPlayer.start();
    }

    @Override
    public void onClick(View v) {

        if(v == start)
        {
            startService(new Intent(this,MyService.class));
        }
else if(v == stop){
    stopService(new Intent(this,MyService.class));
        }



    }
}

package com.fyp.riphah.myservice;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.provider.Settings;

import androidx.annotation.Nullable;

import java.security.Provider;
import java.util.List;
import java.util.Map;

public class MyService extends Service {


    private  MediaPlayer mediaPlayer;
    @Override
    public void onDestroy() {
        super.onDestroy();
        mediaPlayer.stop();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        mediaPlayer = MediaPlayer.create(this, Settings.System.DEFAULT_ALARM_ALERT_URI);
        mediaPlayer.start();
        mediaPlayer.setLooping(true);
        return START_STICKY;
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}