标签：running 监听事件 end current imp 3.0 void vol poll
在EventBus3.0框架中执行线程的快速切换，通过ThreadMode来指定线程在哪个线程中执行;
在EventBus3.0框架线程模型有个PendingPost 类负责数据的传递;
final class PendingPost { private final static List<PendingPost> pendingPostPool = new ArrayList<PendingPost>(); Object event; Subscription subscription; PendingPost next; private PendingPost(Object event, Subscription subscription) { this.event = event; this.subscription = subscription; } }
PendingPost 类中维护了3个字段，其中event为事件类的实例，subscription是监听回调信息封装，next 的类型也是一个PendingPost ，通过next可以构建一个列表;
在类的内部也维护着一个静态的PendingPost 对象的对象池，当需要PendingPost 实例时，首先从对象池中获取，当获取不到时在进行对象的new创建;
ThreadMode.MAIN 当调用线程不是主线程时，需要把事件执行推送到主线程中，在EventBus3.0框架中的EventBus类中维护着一个HandlerPoster对象来进行主线程数据的处理;HandlerPoster类是一个Handler,监听事件函数的执行应该在主线程回调的handleMessage 方法中,在源码中也确实是在handleMessage方法执行：
eventBus.invokeSubscriber(pendingPost);
ThreadMode.Background 与ThreadMode.AsyncPoster 执行的方式差不多相同，都是从后台线程池中取出线程进行执行;在EventBus类中初始化了BackgroundPoster与AsyncPoster来对这2种线程模型进行处理，这2个类都继承了Runnable 接口;
final class BackgroundPoster implements Runnable { private final PendingPostQueue queue; private final EventBus eventBus; private volatile boolean executorRunning; BackgroundPoster(EventBus eventBus) { this.eventBus = eventBus; queue = new PendingPostQueue(); } public void enqueue(Subscription subscription, Object event) { PendingPost pendingPost = PendingPost.obtainPendingPost(subscription, event); synchronized (this) { queue.enqueue(pendingPost); if (!executorRunning) { executorRunning = true; eventBus.getExecutorService().execute(this); } } } }
在BackgroundPoster 类中PendingPostQueue 是一个存储了PendingPost类型的队列，eventBus对应的就是EventBus类的实例,在BackgroundPoster 类中enqueue方法是在EventBus分发Post方法内部进行调用的;
eventBus.getExecutorService()获取EventBus类中的ExecutorService,在源码我们可以发现ExecutorService=Executors.newCachedThreadPool();
当执行eventBus.getExecutorService().execute(this);代码时,就跳转到BackgroundPoster 的run方法中
@Override public void run() { try { try { while (true) { PendingPost pendingPost = queue.poll(1000); if (pendingPost == null) { synchronized (this) { // Check again, this time in synchronized pendingPost = queue.poll(); if (pendingPost == null) { executorRunning = false; return; } } } eventBus.invokeSubscriber(pendingPost); } } catch (InterruptedException e) { Log.w("Event", Thread.currentThread().getName() + " was interruppted", e); } } finally { executorRunning = false; } }
从run方法中可以看出，最终执行的还是eventBus.invokeSubscriber(pendingPost) 方法;
标签：running 监听事件 end current imp 3.0 void vol poll
原文地址：http://www.cnblogs.com/h20064528/p/6769054.html
