我应该如何向Service的线程中添加处理程序

如何解决我应该如何向Service的线程中添加处理程序

|| 我仍在研究Pro Android 2的简短Service示例（第304页），该Service示例又由两个类组成：下面显示的BackgroundService.java和下面显示的MainActivity.java。现在，我想扩展此代码以将数据传递到应用程序中的另一个活动。从学到的知识，我将处理程序的开头添加到以下代码中：

    public class MainActivity extends Activity {
        private static final String TAG = \"MainActivity\";

        @Override
        public void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            Log.d(TAG,\"starting service\");

            Button bindBtn = (Button)findViewById(R.id.bindBtn);
            bindBtn.setonClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    Intent backgroundService = new Intent(MainActivity.this,com.marie.mainactivity.BackgroundService.class);
                    startService(backgroundService);
                }
            });

            Button unbindBtn = (Button)findViewById(R.id.unbindBtn);
            unbindBtn.setonClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    stopService(new Intent(MainActivity.this,BackgroundService.class));
                }
            });
        }
    }

    // The handler code I added
    // I\'m not sure what fills out the msg.what field for the switch
    private Handler messageHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {  
            switch(msg.what) {
                //handle update
                //possibly update another activity???
            }
        }

    };

    public class BackgroundService extends Service {
        private notificationmanager notificationMgr;

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

            notificationMgr = notificationmanager)getSystemService(NOTIFICATION_SERVICE);

            displayNotificationMessage(\"starting Background Service\");

            Thread thr = new Thread(null,new ServiceWorker(),\"BackgroundService\");
            thr.start();
        }   

        class ServiceWorker implements Runnable
        {
            public void run() {
                mResult = doSomethingTimeConsuming();

                //Use the handler to send update to the main thread or another activity???
                messageHandler.sendMessage(Message.obtain(messageHandler,mResults));

                BackgroundService.this.stopSelf();
            }
        }

        @Override
        public void onDestroy()
        {
            displayNotificationMessage(\"stopping Background Service\");
            super.onDestroy();
        }

        @Override
        public void onStart(Intent intent,int startId) {
            super.onStart(intent,startId);
        }

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

        private void displayNotificationMessage(String message)
        {
            Notification notification = new Notification(R.drawable.note,message,System.currentTimeMillis());

            PendingIntent contentIntent = PendingIntent.getActivity(this,new Intent(this,MainActivity.class),0);

            notification.setLatestEventInfo(this,\"Background Service\",contentIntent);

            notificationMgr.notify(R.id.app_notification_id,notification);
        }
    }

我了解到，当我获得Service实例时，可以将其传递给Handler。但是我不知道该怎么做。     

解决方法

        如果要将信息从服务发送到活动，请使用广播接收器。将广播接收器作为您的活动的内部类，这样它就可以访问活动的数据。然后注册广播：

IntentFilter filter = new IntentFilter(\"com.damluar.intent.action.NEWTWEETS\");
broadcastReceiver = new NewTweetsReceiver();
registerReceiver(broadcastReceiver,filter);

然后从服务中，您可以通过意图将数据发送到广播（和外部活动）：

sendBroadcast(new Intent(\"com.damluar.intent.action.NEWTWEETS\"));

    ,        您可以在

BackgroundSerivce

类中定义

setHandler(Handler handler)

setter函数，并在启动服务之前从

MainActivity

中调用它，并以这种方式传递处理程序。