Android RoboGuice 使用指南(19):发送接收Events

Roboguice 提供了对Context 生命周期相关的事件的send 和receive ,系统缺省支持的事件为：

• OnActivityResultEvent
• OnConfigurationChangedEvent
• OnContentChangedEvent
• OnContentViewAvailableEvent
• OnCreateEvent
• OnDestroyEvent
• OnNewIntentEvent
• OnPauseEvent
• OnRestartEvent
• OnResumeEvent
• OnStartEvent
• OnStopEvent

一个简单的例子如下：

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!") }}

有关Events的注意事项如下：

• 在Context中使用@Inject定义事件的Listener.
• Event只能在某一特定的Context（Activity）中传送，不能跨Context发送，接受。
• Event除了提供上面列出的Context相关事件外，也可以使用自定义的事件。
• @observes 只能应用到方法上，而不能应用到构造函数上。

下面使用一个自定义事件MyEvent，通过observer 这个自定义事件来发送，接收自定义事件。

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.}

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