Activity和Service之间通信,最简单的方式就是通过broadcast广播来实现,但针对一些频繁的数据传输,用广播来实现,性能上会降低很多,例如:更新下载进度等
接下来介绍下handler来代替broadcast来实现Activity和Service之间通信,这样性能会高些。
(1) 在Service的onBind里实例messenger对象,并把handler包装进去,并将此messenger返回,代码如下:
@Override public IBinder onBind(Intent intent) { // 创建Messenger对象包含handler引用 Messenger messenger = new Messenger(handler); // 返回Messenger的binder return messenger.getBinder(); } (2) 在Activity中通过bindService来打开service // 绑定service Intent sIntent = new Intent(this, DownService.class); bindService(sIntent, conn, Service.BIND_AUTO_CREATE); 在ServiceConnection中来接受Service传过来的messenger,通过onServiceConnected的第二个参数service来实例化Messenger,即为service中传递过来的messenger private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { } @Override public void onServiceConnected(ComponentName name, IBinder service) { // 获取service中的messenger serviceMessenger = new Messenger(service); } };然后通过该serviceMassenger来,来发送Message,再后Service中的handler就会接受到这个Message了发送代码如下:
// 使用service中的messenger来发送消息 try { Message msg = new Message(); msg.what = DownService.MSG_BIND; serviceMessenger.send(msg); } catch (RemoteException e) { e.printStackTrace(); }(1) 可以在Activity的onServiceConnected方法中实例Activity的Messenger,然后再将Activity中的handler包装在Messenger中,创建Message将replyTo属性指向给Activity的Messenger,最后再通过Service的Messenger来将此Messenger传递给Service ,代码如下
private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { } @Override public void onServiceConnected(ComponentName name, IBinder service) { // 获取service中的messenger serviceMessenger = new Messenger(service); // 创建Activity中的messenger Messenger messenger = new Messenger(mHandler); // 创建消息 Message msg = new Message(); msg.what = DownService.MSG_BIND; msg.replyTo = messenger; // 使用service中的messenger发送Activity中的messenger try { serviceMessenger.send(msg); } catch (RemoteException e) { e.printStackTrace(); } } };(2) 在Service中,通过handler,将Activity传过来的messenger接受即可。通过传过来的activityMessenger来进行发消息即可完成通信
Handler handler = new Handler() { public void handleMessage(android.os.Message msg) { FileEntity fileEntity = null; switch (msg.what) { case MSG_BIND: // 接受来自Activity的messenger activityMessenger = msg.replyTo; break; default: break; } }; }; 以上是Activity和Service之间通过Handler通信步骤,欢迎交流探讨哈。