EventBus

最新推荐文章于 2024-04-17 09:37:06 发布

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本文详细介绍EventBus的使用方法，包括事件定义、事件处理、不同线程处理方式、粘性事件及优先级设置等内容。

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参考网址:http://greenrobot.org/eventbus/

引入EventBus:
compile 'org.greenrobot:eventbus:3.0.0'

1.快速入门

step1：定义事件
public class MessageEvent {
  public final String message;

  public MessageEvent(String message) {
  this.message = message;
  }
}
step2:接收并处理事件

相应生命周期方法中注册和解注册

@Override
public void onStart() {
super.onStart();
EventBus.getDefault().register(this);
}

@Override
public void onStop() {
EventBus.getDefault().unregister(this);
super.onStop();
}

定义处理事件方法

// This method will be called when a MessageEvent is posted (in the UI thread for Toast)
@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessageEvent(MessageEvent event) {
Toast.makeText(getActivity(), event.message, Toast.LENGTH_SHORT).show();
}
// This method will be called when a SomeOtherEvent is posted
@Subscribe
public void handleSomethingElse(SomeOtherEvent event) {
doSomethingWith(event);
}

step3:发送事件

EventBus.getDefault().post(new MessageEvent("Hello everyone!"));

2.定义不同线程中处理事件

@Subscribe(threadMode = ThreadMode.POSTING) // 和发布者在同一个线程，默认的
public void onMessage(MessageEvent event) {
log(event.message);
}

// UI线程处理
@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessage(MessageEvent event) {
textField.setText(event.message);
}

// 后台线程处理
@Subscribe(threadMode = ThreadMode.BACKGROUND)
public void onMessage(MessageEvent event){
saveToDisk(event.message);
}

// 单独的一个线程线程池机制
@Subscribe(threadMode = ThreadMode.ASYNC)
public void onMessage(MessageEvent event){
backend.send(event.message);
}

3.Sticky Events 粘性事件

使用场景：例如想要在Activity初始化前发送事件在Activity启动后执行

发送一个粘性事件：EventBus.getDefault().postSticky(new MessageEvent("Hello everyone!"));

处理接收

@Override
  public void onStart() {
  super.onStart();
EventBus.getDefault().register(this);
  }

@Subscribe(sticky = true, threadMode = ThreadMode.MAIN)
  public void onEvent(MessageEvent event) {
  // UI updates must run on MainThread
textField.setText(event.message);
  }

@Override
  public void onStop() {
EventBus.getDefault().unregister(this);
  super.onStop();
  }

获取或销毁粘性对象

MessageEvent stickyEvent = EventBus.getDefault().getStickyEvent(MessageEvent.class);
// Better check that an event was actually posted before
if(stickyEvent != null) {
// "Consume" the sticky event
EventBus.getDefault().removeStickyEvent(stickyEvent);
// Now do something with it
}

4.优先级

默认优先级是0 优先级越高先执行不过不能影响不同线程之间的接收

@Subscribe(priority = 1);
public void onEvent(MessageEvent event) {
…
}

可以在高优先级截断低优先级的处理

@Subscribe
public void onEvent(MessageEvent event){
// Process the event
…

EventBus.getDefault().cancelEventDelivery(event) ;
}

5.混淆

-keepattributes *Annotation*
-keepclassmembers class ** {
@org.greenrobot.eventbus.Subscribe <methods>;
}
-keep enum org.greenrobot.eventbus.ThreadMode { *; }

# Only required if you use AsyncExecutor
-keepclassmembers class * extends org.greenrobot.eventbus.util.ThrowableFailureEvent {
<init>(java.lang.Throwable);
}