eventbus/documentation/how-to-get-started/

最新推荐文章于 2025-08-20 15:37:55 发布

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最新推荐文章于 2025-08-20 15:37:55 发布

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本文介绍如何使用EventBus简化Android应用中的事件处理。首先，在Gradle中添加依赖；其次，定义事件类并实现订阅者方法；最后，从代码的任意位置发布事件。遵循这三步即可轻松实现组件间的解耦。

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How to get started with EventBus in 3 steps

EventBus’ API is as easy as 1-2-3. Before we get started with the 3 basic steps, let’s add the EventBus depency to your Gradle script (make sure you are using the latest version):

compile 'org.greenrobot:eventbus:3.0.0'

Step 1: Define events

Events are POJO (plain old Java object) without any specific requirements.

public class MessageEvent {
  public final String message;

  public MessageEvent(String message) {
  this.message = message;
  }
}

Step 2: Prepare subscribers

Subscribers implement event handling methods (also called “subscriber methods”) that will be called when an event is posted. These are defined with the @Subscribe annotation. Please note that with EventBus 3 the method name can be chosen freely (no naming conventions like in EventBus 2).

// This method will be called when a MessageEvent is posted
@Subscribe
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);
}

Subscribers also need to register and unregister themselves to the bus. Only while subscribers are registered, they will receive events. In Android, Activities and Fragments usually bind according to their life cycle:

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

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