Android 服务如何持续更新 TextView？

Question

我想创建一个持续更新 Textview 的服务，即使我运行另一个应用程序也是如此。如果我按下停止按钮，服务将停止。在下面的代码中，我结合使用了服务和 BroadcastReceiver，但如果我更改应用程序，服务不会更新 TextView。

代码：

服务

public class ChronometerService extends Service
{
    public static final String BROADCAST_ACTION = "com.example.test";
    private final Handler handler = new Handler();
    private Intent intent = null;
    int counter = 0;

    @Override
    public void onCreate()
    {
        super.onCreate();

        intent = new Intent( BROADCAST_ACTION );
    }

    @Override
    public void onStart( Intent intent, int startId )
    {
        //handler.removeCallbacks( sendUpdatesToUI );
        handler.postDelayed( sendUpdatesToUI, 1000 );
    }


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


    private Runnable sendUpdatesToUI = new Runnable()
    {
        @Override
        public void run() 
        {
            DisplayLoggingInfo();
            handler.postDelayed( this, 1000 );
        }
    };


    private void DisplayLoggingInfo()
    {
        counter += 1;
        //chrono.start();
        intent.putExtra( "TIME", String.valueOf(counter) );
        sendBroadcast( intent );
    }


    @Override
    public void onDestroy()
    {   
        //chrono.stop();
        //chrono.setBase( SystemClock.elapsedRealtime() );
        handler.removeCallbacks( sendUpdatesToUI );     
        super.onDestroy();
    }       
}

Activity

public class MainActivity extends Activity 
{
    public static TextView chronometer1 = null;
    private Intent intent;

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

        intent = new Intent( MainActivity.this, ChronometerService.class );
    }


    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver()
    {
        @Override
        public void onReceive( Context context, Intent intent )
        {
            updateUI( intent );       
        }
    };

    private void updateUI( Intent intent )
    {
        String time = intent.getStringExtra( "TIME" );
        chronometer1 = ( TextView ) findViewById( R.id.chronometer1 );
        chronometer1.setText( time );
    }

    public void start( View v )
    {
        startService( intent );
        registerReceiver(broadcastReceiver, new IntentFilter( ChronometerService.BROADCAST_ACTION ) );
    }

    public void stop( View v )
    {
        unregisterReceiver( broadcastReceiver );
        stopService( intent );
    }
}

Answer 1

我找到了答案：当服务是运行并且我不希望它被 OS 杀死时，我必须使用 startForeground(int id, Notification notification) 方法。

当服务完成正在执行的任何操作并且可以被 OS 终止时，调用 stopForeground(boolean removeNotification)。 "startForeground" 需要通知作为参数，因为每个前台服务都必须显示通知以便用户意识到这一点。

还有助于在清单文件中的服务声明中设置属性：

android:process=":some name here"

Android 服务如何持续更新 TextView？

How an Android service update a TextView continuously?

android

android-service

android-broadcast