android - 访问服务的变量

Question

我有一个名为 Main 的 Android Activity，它调用一个名为 MainService 的服务，如下所示:

Intent intent = new Intent(this, MainService.class);
if(MainService.getInstance() == null){
  Log.d(TAG, "Calling MainService");
  startService(intent);
}

MainService 在其生命周期内维护一个变量，我希望稍后在 Main 中访问该变量。我该怎么做？

谢谢。

Answer 1

您可以绑定(bind)服务并永久拥有服务实例。下面的示例代码将帮助您:-
服务等级

public class MusicService extends Service {

    MyBinder binder=new MyBinder();
    MusicService services;
    static  Context context;
    @Override
    public IBinder onBind(Intent arg0) {
        // TODO Auto-generated method stub
        return binder;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        context=getApplicationContext();

        MediaPlayer mPlayer = MediaPlayer.create(getApplicationContext(), R.raw.yaar);
        mPlayer.start();
    }

    public class MyBinder extends Binder
    {
        public MusicService getServiceSystem()
        {
            return MusicService.this;
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }
}

Activity

public class MainActivity extends AppCompatActivity {

    MusicService services;

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

        ServiceConnection connection=new ServiceConnection() {
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
              MusicService.MyBinder binderr=(MusicService.MyBinder)service;
                services=binderr.getServiceSystem();
            }

            @Override
            public void onServiceDisconnected(ComponentName name) {

            }
        };

        Intent intent= new Intent(this, MusicService.class);
        startService(intent);
    }

}

然后您可以在 Activity 中需要的任何地方使用服务。希望对您有所帮助。