EventBus 3

EventBus 是一個(gè)基于觀察者模式的事件發(fā)布/訂閱框架

資料

Github
Documentation

Eventbus
老司機(jī)教你 “飆” EventBus 3

設(shè)置

導(dǎo)入

• 配置模組的 build.gradle

android {
    defaultConfig {
        javaCompileOptions {
            annotationProcessorOptions {
                arguments = [ eventBusIndex : 'com.example.myapp.MyEventBusIndex' ] // 索引全名
            }
        }
    }
}

dependencies {
    compile 'org.greenrobot:eventbus:3.0.0'
    annotationProcessor 'org.greenrobot:eventbus-annotation-processor:3.0.1'
}

初始化

// 設(shè)置為默認(rèn)屬性
EventBus.builder().addIndex(new MyEventBusIndex()).installDefaultEventBus();
EventBus eventBus = EventBus.getDefault(); // 設(shè)置完后，使用默認(rèn)即可

// 或者在使用時(shí)再設(shè)置
EventBus eventBus = EventBus.builder().addIndex(new MyEventBusIndex()).build();

// 如果庫(kù)中有EventBusIndex，需要多次添加
EventBus eventBus = EventBus.builder()
    .addIndex(new MyEventBusAppIndex())
    .addIndex(new MyEventBusLibIndex())
    .build();

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);
}

基本用法

定義事件Event

public class MessageEvent {

    public final String message;

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

注冊(cè)

訂閱之前需要注冊(cè)，activities和fragments一般在 onStart/onStop 中調(diào)用

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

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

訂閱

四種線程模式，ThreadMode: POSTING/MAIN/BACKGROUND/ASYNC

// 在發(fā)送事件的線程調(diào)用，同步處理
@Subscribe
public void handleSomethingElse(SomeOtherEvent event) {
    doSomethingWith(event);
}

// 主線程調(diào)用
@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessageEvent(MessageEvent event) {
    Toast.makeText(getActivity(), event.message, Toast.LENGTH_SHORT).show();
}

// 子線程調(diào)用，非主線程則直接調(diào)用，主線程則開(kāi)單線程調(diào)用
@Subscribe(threadMode = ThreadMode.BACKGROUND)
public void onMessage(MessageEvent event){
    saveToDisk(event.message);
}

// 異步調(diào)用，使用線程池在不同的線程調(diào)用
@Subscribe(threadMode = ThreadMode.ASYNC)
public void onMessage(MessageEvent event){
    backend.send(event.message);
}

發(fā)送

任意地方發(fā)送事件，匹配的事件訂閱方法會(huì)接收事件

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

優(yōu)先級(jí)

@Subscribe(priority = 1); // 優(yōu)先級(jí)，默認(rèn)為0
public void onEvent(MessageEvent event) {

  // 取消傳遞，只能運(yùn)行在ThreadMode.PostThread
  EventBus.getDefault().cancelEventDelivery(event);
}

粘性事件 Sticky Event

事件發(fā)出后一直保存在內(nèi)存中，訂閱方法在之后注冊(cè)也能完成訂閱

用法

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

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

@Subscribe(sticky = true, threadMode = ThreadMode.MAIN)
public void onEvent(MessageEvent event) {
    textField.setText(event.message);
}

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

取消事件

MessageEvent stickyEvent = EventBus.getDefault().getStickyEvent(MessageEvent.class);
if(stickyEvent != null) {
    EventBus.getDefault().removeStickyEvent(stickyEvent);
}

MessageEvent stickyEvent = EventBus.getDefault().removeStickyEvent(MessageEvent.class);
if(stickyEvent != null) {
}

配置

無(wú)訂閱時(shí)無(wú)日志

EventBus eventBus = EventBus.builder()
    .logNoSubscriberMessages(false)
    .sendNoSubscriberEvent(false)
    .build();

拋異常

EventBus eventBus = EventBus.builder().throwSubscriberException(true).build();

修改默認(rèn)

EventBus.builder().throwSubscriberException(BuildConfig.DEBUG).installDefaultEventBus();

異步執(zhí)行器 AsyncExecutor

• AsyncExecutor就像一個(gè)帶異常處理的線程池
• 異常被自動(dòng)捕獲包裹成ThrowableFailureEvent并發(fā)送

用法

AsyncExecutor.create()  // 在 Application 中創(chuàng)建保存實(shí)例
        .execute(new AsyncExecutor.RunnableEx() {
                     @Override
                     public void run() throws LoginException {
                         // 不需要捕獲異常
                         remote.login();
                         EventBus.getDefault().postSticky(new LoggedInEvent());
                     }
                 }
        );
}

@Subscribe(threadMode = ThreadMode.MAIN)
public void handleLoginEvent(LoggedInEvent event) {
}

@Subscribe(threadMode = ThreadMode.MAIN)
public void handleFailureEvent(ThrowableFailureEvent event) {
  // 處理異常
}

自定義

• AsyncExecutor.builder()
• 可定義EventBus實(shí)例、線程池、失敗事件類(lèi)、作用域