Android RoboGuice使用指南(19) 發送接收Events

Roboguice 提供了對Context 生命周期相關的事件的send 和receive ,系統缺 省支持的事件為：

OnActivityResultEvent

OnConfigurationChangedEvent

OnContentC hangedEvent

OnContentViewAvailableEvent

OnCreateEvent

OnDestroyEv ent

OnNewIntentEvent

OnPauseEvent

OnRestartEvent

OnResumeEvent< p>OnStartEvent

OnStopEvent

一個簡單的例子如下：

public 

class MyActivity extends RoboActivity {
 // You must "register" your listener in the current
 // context by injecting it.
 // Injection is commonly done here in the activity,
 //but can also be done anywhere really.
 @Inject protected MyListeners myListeners;

}
          
// In this example, all the listeners are in a     
// MyListeners class, but really they could     
// be anywhere as long as it's registered.     
// You can even put the listeners directly into     
// your activity classes if you like!     
class MyListeners {     

 // Any method with void return type and a     
 // single parameter with @Observes annotation     
 // can be used as an event listener.     
 //This one listens to onResume.     
 public void doSomethingOnResume(     
 @Observes OnResumeEvent onResume ) {     
 Ln.d("Called doSomethingOnResume in onResume");     
 }     

 // As you might expect, some events can     
 //have parameters.  The OnCreate event     
 // has the savedInstanceState parameter that     
 //Android passes to onCreate(Bundle)     
 public void doSomethingElseOnCreate(     
 @Observes OnCreateEvent onCreate ) {     
 Ln.d("onCreate savedInstanceState is %s",     
 onCreate.getSavedInstanceState())     
 }     

 // And of course, you can have multiple     
 //listeners for a given event.     
 // Note that ordering of listener execution     
 //is indeterminate!     
 public void xxx( @Observes OnCreateEvent onCreate ) {     
 Ln.d("Hello, world!")     
 }     
}

有關Events的注意事項如下：

在Context中使用@Inject定義事件的 Listener.

Event只能在某一特定的Context（Activity）中傳送，不能跨 Context發送，接受。

Event除了提供上面列出的Context相關事件外，也可以 使用自定義的事件。

@observes 只能應用到方法上，而不能應用到構造函數上 。

下面使用一個自定義事件MyEvent，通過observer 這個自定義事件來發 送，接收自定義事件。

public 

class EventDemo extends RoboActivity {     
          
 @Inject protected EventManager eventManager;     
 @InjectView (R.id.button) Button button;     
          
 @Override 
 public void onCreate(Bundle savedInstanceState) {     
 super.onCreate(savedInstanceState);     
 setContentView(R.layout.eventdemo);     
 button.setOnClickListener(mGoListener);     
 }     

 private OnClickListener mGoListener = new OnClickListener()     
 {     
 public void onClick(View v)     
 {     
 eventManager.fire(EventDemo.this,new MyEvent());     
 }     
 };     

 protected void handleEvent(@Observes MyEvent event){     
 Toast.makeText(this, "Custom event",     
 Toast.LENGTH_LONG).show();     
 }     
}     
          
class MyEvent{     
 //put any memeber you want here.     
}

本例下載： http://www.imobilebbs.com/download/android/roboguice/EventDemo.zip

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