展示一段用service实现本地音乐播放并通过Activity进行交互的示例代码

以下是一个用 service 实现本地音乐播放并通过 Activity 进行交互的示例代码：

1. 在 AndroidManifest.xml 文件中添加如下代码：

<service android:name=".MusicService" />

2. 创建 MusicService.java：

public class MusicService extends Service implements MediaPlayer.OnPreparedListener {

    private MediaPlayer mediaPlayer;
    private String musicPath;

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

    public void playMusic(String path) {
        musicPath = path;
        if (mediaPlayer == null) {
            mediaPlayer = new MediaPlayer();
            mediaPlayer.setOnPreparedListener(this);
        } else {
            mediaPlayer.reset();
        }
        try {
            mediaPlayer.setDataSource(path);
            mediaPlayer.prepareAsync();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void pauseMusic() {
        if (mediaPlayer != null) {
            mediaPlayer.pause();
        }
    }

    public void resumeMusic() {
        if (mediaPlayer != null) {
            mediaPlayer.start();
        }
    }

    public class MusicBinder extends Binder {

        public MusicService getService() {
            return MusicService.this;
        }

    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        mp.start();
    }

    @Override
    public void onDestroy() {
        if (mediaPlayer != null) {
            mediaPlayer.release();
            mediaPlayer = null;
        }
        super.onDestroy();
    }

}

3. 创建 MusicActivity.java：

public class MusicActivity extends AppCompatActivity {

    private MusicService musicService;
    private boolean isBound = false;

    private TextView textView;
    private EditText editText;
    private Button playButton;
    private Button pauseButton;
    private Button resumeButton;

    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            MusicService.MusicBinder binder = (MusicService.MusicBinder) service;
            musicService = binder.getService();
            isBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            isBound = false;
        }
    };

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

        textView = findViewById(R.id.textView);
        editText = findViewById(R.id.editText);
        playButton = findViewById(R.id.playButton);
        pauseButton = findViewById(R.id.pauseButton);
        resumeButton = findViewById(R.id.resumeButton);

        playButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isBound) {
                    String path = editText.getText().toString();
                    musicService.playMusic(path);
                }
            }
        });

        pauseButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isBound) {
                    musicService.pauseMusic();
                }
            }
        });

        resumeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isBound) {
                    musicService.resumeMusic();
                }
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        Intent intent = new Intent(this, MusicService.class);
        bindService(intent, serviceConnection, BIND_AUTO_CREATE);
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (isBound) {
            unbindService(serviceConnection);
            isBound = false;
        }
    }

}

4. 创建 activity_music.xml 布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请输入本地音乐路径：" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="sdcard/music.mp3" />

    <Button
        android:id="@+id/playButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="播放" />

    <Button
        android:id="@+id/pauseButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="暂停" />

    <Button
        android:id="@+id/resumeButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="继续" />

</LinearLayout>

通过这个示例代码，可以实现本地音乐的播放、暂停和继续操作，并且使用 service 可以在后台进行音乐播放，同时又可以与 Activity 进行交互。