activity与service使用Messenger通信.doc

Android开发Activity与service使用Messenger通信Messenger对象可以发送Message，送出的消息放在消息池中，由主线程依次取出，交给和Message关联的Handle处理，而Messenger可以在创建时和Handle对象关联，所以由哪个Messenger发出的Message，就可以由和这个Messenger关联的Handle处理。所以为了实现Activity和Service的通信，我们可以在Activity和Service中分别定义一个Handle类，用来处理和这个Handle相关联的Messenger发出的Message。并且用这个类对象去创建Messenger对象。具体例子如下：Activity的代码public class SimpleMathServiceDemo extends Activity /private MathService mathService;private Messenger sMessenger=null;private boolean isBound = false;TextView labelView;private final Messenger aMessenger=new Messenger(new ActivityHandle(); class ActivityHandle extends HandlerOverridepublic void handleMessage(Message msg) / TODO Auto-generated method stubBundle bundle=new Bundle();bundle=msg.getData();labelView.setText(bundle.getCharSequence(fromservice);super.handleMessage(msg); Override public void onCreate(Bundle savedInstanceState) super.onCreate(savedInstanceState); setContentView(R.layout.main); labelView = (TextView)findViewById(R.id.label); Button bindButton = (Button)findViewById(R.id.bind); Button unbindButton = (Button)findViewById(R.id.unbind); Button computButton = (Button)findViewById(R.pute); bindButton.setOnClickListener(new View.OnClickListener()Overridepublic void onClick(View v) if(!isBound)final Intent serviceIntent = new Intent(SimpleMathServiceDemo.this,MathService.class);bindService(serviceIntent,mConnection,Context.BIND_AUTO_CREATE);isBound = true; ); unbindButton.setOnClickListener(new View.OnClickListener()Overridepublic void onClick(View v) if(isBound)isBound = false;unbindService(mConnection); ); computButton.setOnClickListener(new View.OnClickListener()Overridepublic void onClick(View v) if(sMessenger!=null)try Bundle bundle=new Bundle();bundle.putString(fromActivity, 从Activity发向Service);Message msg=Message.obtain();msg.setData(bundle);msg.replyTo=aMessenger;sMessenger.send(msg); catch (RemoteException e) / TODO Auto-generated catch blocke.printStackTrace();elselabelView.setText(没有启动服务！); ); private ServiceConnection mConnection = new ServiceConnection() Overridepublic void onServiceConnected(ComponentName name, IBinder service) Log.i(Service, onServiceConnected);sMessenger=new Messenger(service);Overridepublic void onServiceDisconnected(ComponentName name) sMessenger=null;Log.i(Service, onServiceDisconnected); ;Overridepublic boolean bindService(Intent service, ServiceConnection conn, int flags) / TODO Auto-generated method stubLog.i(Service, bindService);return super.bindService(service, conn, flags); Service中的代码：public class MathService extends Serviceprivate final Messenger sMessenger = new Messenger(new ServiceHandle();public Messenger aMessenger=null;public class ServiceHandle extends HandlerOverridepublic void handleMessage(Message msg) / TODO Auto-generated method stubBundle bundle=new Bundle();bundle=msg.getData();aMessenger=msg.replyTo;Toast.makeText(MathService.this, bundle.get(fromActivity).toString(), Toast.LENGTH_LONG).show();Bundle bundle1=new Bundle();bundle1.putString(fromservice, 从service到activity);Message msg1=Message.obtain();msg1.setData(bundle1);try aMessenger.send(msg1); catch (RemoteException e) / TODO Auto-generated catch blocke.printStackTrace();super.handleMessage(msg);public class LocalBinder extends BinderMathService getService() return MathService.this; Overridepublic IBinder onBind(Intent intent) Toast.makeText(this, 本地绑定：MathService, Toast.LENGTH_SHORT).show(); Log.i(Service, onBind);return sMessenger.getBinder();Overridepublic boolean onUnbind(Intent intent) Toast.makeText(this, 取消本地绑定：MathService, Toast.LENGTH_SHORT).show(); Log.i(Service, onUnbind);return false;Overridepublic void onCreate() / TODO Auto-generated method stubsuper.onCreate();Log.i(Service, onCreat);Overridepublic void onDestroy() / TODO Auto-generated method stubsuper.onDestroy();Log.i(Service, onDestroy);Overridepublic void onRebind(Intent intent) / TODO Auto-generated method stubsuper.onRebind(intent);Log.i(Service, onRebind);Overridepublic void onStart(Intent intent, int startId) / TODO Auto-generated method stubsuper.onStart(intent, startId);Log.i(Service, onStart);例中，Activity中定义了ActivityHandle类，并重载了public void handleMessage(Message msg)方法用来处理和该Handle关联的消息。并通过private final Messenger aMessenger=new Messenger(new ActivityHandle();创建了Activity的数据成员aMessenger，如果Service能获取aMessenger对象，那么就可以利用它给Activity传递消息了。同样，Service中也定义了ServiceHandle类，并通过private final Messenger sMessenger=new Messenger(new ServiceHandle();创建了Service的数据成员sMessenger，如果Activity能获取sMessenger对象，那么就可以利用它给Service传递消息了。那么Activity如何获取Service的Messenger呢，它是通过Activity调用Service过程中传递过来的参数IBinder对象，通过构造方法创建的sMessenger对象，其中IBinder对象和S