post → @Subscribe 方法流程
1.post 调用EventBus this.dispatcher.dispatch(event, eventSubscribers);
2.dispatcher = Dispatcher.perThreadDispatchQueue()
3. new Dispatcher.PerThreadQueuedDispatcher() = new PerThreadQueuedDispatcher(queue,dispatching)
4. PerThreadQueuedDispatcher.dispatch = while(nextEvent.subscribers.hasNext()) {
((Subscriber)nextEvent.subscribers.next()).dispatchEvent(nextEvent.event);
}
到此 post跟踪完毕 现在就是要知道 nextEvent 是谁
1. nextEvent = new Dispatcher.PerThreadQueuedDispatcher.Event(event, subscribers)
继续追 event,subscribers
发现是最开始 post传进来的,
现在我们要明白一件事情 post 就是 调用了 eventSubscribers里面的dispatchEvent,开始追subscribers
2.Iterator<Subscriber> eventSubscribers = this.subscribers.getSubscribers(event);
3.
Iterator<Subscriber> getSubscribers(Object event) {
ImmutableSet<Class<?>> eventTypes = flattenHierarchy(event.getClass());
List<Iterator<Subscriber>> subscriberIterators = Lists.newArrayListWithCapacity(eventTypes.size());
UnmodifiableIterator var4 = eventTypes.iterator();
while(var4.hasNext()) {
Class<?> eventType = (Class)var4.next();
CopyOnWriteArraySet<Subscriber> eventSubscribers = (CopyOnWriteArraySet)this.subscribers.get(eventType);
if (eventSubscribers != null) {
**subscriberIterators.add(eventSubscribers.iterator());**
}
}
return Iterators.concat(subscriberIterators.iterator());
}
4. 发现eventSubscribers 是从this.subscribers拿的开始追this.subscribers
5.
void register(Object listener) {
Multimap<Class<?>, Subscriber> listenerMethods = this.findAllSubscribers(listener);
Collection eventMethodsInListener;
CopyOnWriteArraySet eventSubscribers;
for(Iterator var3 = listenerMethods.asMap().entrySet().iterator(); var3.hasNext(); eventSubscribers.addAll(eventMethodsInListener)) {
Entry<Class<?>, Collection<Subscriber>> entry = (Entry)var3.next();
Class<?> eventType = (Class)entry.getKey();
eventMethodsInListener = (Collection)entry.getValue();
eventSubscribers = (CopyOnWriteArraySet)this.subscribers.get(eventType);
if (eventSubscribers == null) {
CopyOnWriteArraySet<Subscriber> newSet = new CopyOnWriteArraySet();
eventSubscribers = (CopyOnWriteArraySet)MoreObjects.firstNonNull(this.subscribers.putIfAbsent(eventType, newSet), newSet);
}
}
}
6.发现了,eventSubscribers这个是在register做的初始化
看看我们register传了什么
7.
EventBus eventBus = new EventBus();
eventBus.register(new EventListener());
eventBus.post(1);
8.class EventListener {
@Subscribe
public void listenInteger(Integer param) {
System.out.println("EventListener#listenInteger ->" + param);
}
@Subscribe
public void listenInteger2(Integer param) {
System.out.println("EventListener#listenInteger2 ->" + param);
}
@Subscribe
public void listenString(String param) {
System.out.println("EventListener#listenString ->" + param);
}
}
9.明白明白了,this.subscribers里面就是我们传入的带有Subscribe注解各种方法,
10.并且这些方法在
private Multimap<Class<?>, Subscriber> findAllSubscribers(Object listener) {
Multimap<Class<?>, Subscriber> methodsInListener = HashMultimap.create();
Class<?> clazz = listener.getClass();
UnmodifiableIterator var4 = getAnnotatedMethods(clazz).iterator();
while(var4.hasNext()) {
Method method = (Method)var4.next();
Class<?>[] parameterTypes = method.getParameterTypes();
Class<?> eventType = parameterTypes[0];
methodsInListener.put(eventType, Subscriber.create(this.bus, listener, method));
}
return methodsInListener;
}
包装成了Subscriber
11.现在我们只要看 Subscriber的dispatchEvent就知道到底干了什么了
12.
final void dispatchEvent(final Object event) {
this.executor.execute(new Runnable() {
public void run() {
try {
Subscriber.this.invokeSubscriberMethod(event);
} catch (InvocationTargetException var2) {
Subscriber.this.bus.handleSubscriberException(var2.getCause(), Subscriber.this.context(event));
}
}
});
}
@VisibleForTesting
void invokeSubscriberMethod(Object event) throws InvocationTargetException {
try {
this.method.invoke(this.target, Preconditions.checkNotNull(event));
} catch (IllegalArgumentException var3) {
throw new Error("Method rejected target/argument: " + event, var3);
} catch (IllegalAccessException var4) {
throw new Error("Method became inaccessible: " + event, var4);
} catch (InvocationTargetException var5) {
if (var5.getCause() instanceof Error) {
throw (Error)var5.getCause();
} else {
throw var5;
}
}
}
13.发现这不就是调用自己的method了么,到此全部解析完毕。