Android EventBus3.0使用及源码解析
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叨了个叨
最近因为换工作的一些琐事搞的我一个头两个大，也没怎么去学新东西，实在是有些愧疚。新项目用到了EventBus3.0，原来只是听说EventBus的鼎鼎大名，一直没仔细研究过。趁着周末有些时间，研究下代码，也算没有虚度光阴。
EventBus GitHub : https://github.com/greenrobot/EventBus
EventBus3.0简介
EventBus是greenrobot出品的一个用于android中事件发布/订阅的库。以前传递对象可能通过接口、广播、文件等等，尤其像同一个Activity两个Fragment之间采用接口传递对象，十分的麻烦，而且耦合度较高。使用EventBus之后，这些将不再是问题。盗用GiHub上EventBus的一张图。
可以看到，发布者(Publisher)使用post()方法将Event发送到Event Bus，而后Event Bus自动将Event发送到多个订阅者(Subcriber)。这里需要注意两个地方：（1）一个发布者可以对应多个订阅者。（2）3.0以前订阅者的订阅方法为onEvent()、onEventMainThread()、onEventBackgroundThread()和onEventAsync()。在Event Bus3.0之后统一采用注解@Subscribe的形式，具体实现方式见下文。
EventBus3.0的使用
新建两个Activity,花3s扫一下即可。代码如下：
public class MainActivity extends Activity
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 注册EventBus
EventBus.getDefault().register(this);
startActivity(new Intent(this,SecondActivity.class));
@Override
protected void onDestroy()
super.onDestroy();
// 反注册EventBus
EventBus.getDefault().unregister(this);
// 主线程调用
@Subscribe(threadMode = ThreadMode.MAIN)
public void eventBusMain(String str)
Log.i("TAG", "MAIN:"+str+" Thread="+Thread.currentThread().getId());
// 1.发布线程为主线程，新开线程调用
// 2.发布线程为子线程，发布线程调用
@Subscribe(threadMode = ThreadMode.BACKGROUND)
public void eventBusBg(String str)
Log.i("TAG", "BACKGROUND:"+str+" Thread="+Thread.currentThread().getId());
// 在发布线程调用，默认值
@Subscribe(threadMode = ThreadMode.POSTING)
public void eventBusPosting(String str)
Log.i("TAG", "POSTING:"+str+" Thread="+Thread.currentThread().getId());
// 每次都新开线程调用
@Subscribe(threadMode = ThreadMode.ASYNC)
public void eventBusAsync(String str)
Log.i("TAG", "ASYNC:"+str+" Thread="+Thread.currentThread().getId());
public class SecondActivity extends Activity
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
EventBus.getDefault().post("from second activity mainThread: info");
Log.i("TAG", "Post thread="+Thread.currentThread().getId());
new Thread(new Runnable()
@Override
public void run()
EventBus.getDefault().post("from second activity childThread: info");
Log.i("TAG", "Post thread="+Thread.currentThread().getId());
).start();
在MainActivity的onCreate()/onDestroy()中分别注册/反注册EventBus。然后写了四个测试ThreadMode的方法，调用时机注释的很清楚，就不赘述了。最后在SecondActivity的主线程和子线程中分别调用Post()方法，注意，这里Post()方法的参数为Object类型，这也就意味着我们传递任何对象都是可以的，例如JavaBean、List<E>等等都是可以的，这里为了方便演示直接传递了String。Log信息如下：
第一张图中发布者发送线程为主线程，即Post thread = 1，在订阅者收到消息时，ThreadMode = Main和ThreadMode = Posting的方法都在主线程调用，ASYNC和BACKGROUND都新开了线程。图二对比注释同理。
除此之外，Subscribe注解还支持priority和sticky属性。priority设置接收者的优先级，默认值为0。优先级高的方法先被调用，在方法调用完成后可以调用EventBus.getDefault().cancelEventDelivery(event) ;终止优先级低的方法的调用。sticky为粘性事件，默认为关闭状态。能够收到订阅之前发送到的最后一条消息，并且发送的方法不再是post()而是postSticky()。
EventBus3.0源码解析
EventBus是Very的好用。耦合度大大的降低，而且代码十分优雅。它是怎么就做到了这么优雅的呢？知其然，知其所以然。下面就开始一步步的分析。
注解标签Subscribe
对注解不了解的同学可以看下这篇博客。
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Subscribe
ThreadMode threadMode() default ThreadMode.POSTING;
/**
* If true, delivers the most recent sticky event (posted with
* @link EventBus#postSticky(Object)) to this subscriber (if event available).
*/
boolean sticky() default false;
/** Subscriber priority to influence the order of event delivery.
* Within the same delivery thread (@link ThreadMode), higher priority subscribers will receive events before
* others with a lower priority. The default priority is 0. Note: the priority does *NOT* affect the order of
* delivery among subscribers with different @link ThreadModes! */
int priority() default 0;
public enum ThreadMode
POSTING,
MAIN,
BACKGROUND,
ASYNC
注解Subscribe在运行时解析，且只能加在METHOD上。其中有三个方法，threadMode()返回类型ThreadMode为枚举类型，默认值为POSTING，sticky()默认返回false,priority()默认返回0。
1. Register流程
EventBus#getDefault()
public EventBus()
this(DEFAULT_BUILDER);
public static EventBus getDefault()
if (defaultInstance == null)
synchronized (EventBus.class)
if (defaultInstance == null)
defaultInstance = new EventBus();
return defaultInstance;
EventBus采用双重校验锁设计为一个单例模式，奇怪的在于虽然设计为单例模式，但是构造方法确实public类型，这不是坑爹嘛！难道greenrobot在设计EventBus获取实例方法的时候在打LOL，一不小心打错了？原来啊，EventBus默认支持一条事件总线，通常是通过getDefault()方法获取EventBus实例，但也能通过直接new EventBus这种最简单的方式获取多条事件总线，彼此之间完全分开。设计之思想不禁让人拍案叫绝。
EventBus#register()
public void register(Object subscriber)
Class<?> subscriberClass = subscriber.getClass();
List<SubscriberMethod> subscriberMethods = subscriberMethodFinder.findSubscriberMethods(subscriberClass);
synchronized (this)
for (SubscriberMethod subscriberMethod : subscriberMethods)
subscribe(subscriber, subscriberMethod);
首先得到订阅者的报名.类名，即哪个具体类注册。然后调用subscriberMethodFinder.findSubscriberMethods(subscriberClass)，从方法名和返回值来看，findSubscriberMethods()的作用应该是遍历查找订阅者中所有的订阅方法。
SubscriberMethodFinder#findSubscriberMethods()
List<SubscriberMethod> findSubscriberMethods(Class<?> subscriberClass)
// 查找缓存
List<SubscriberMethod> subscriberMethods = METHOD_CACHE.get(subscriberClass);
if (subscriberMethods != null)
// 缓存中有则直接返回
return subscriberMethods;
// 默认false
if (ignoreGeneratedIndex)
subscriberMethods = findUsingReflection(subscriberClass);
else
subscriberMethods = findUsingInfo(subscriberClass);
if (subscriberMethods.isEmpty())
throw new EventBusException("Subscriber " + subscriberClass
+ " and its super classes have no public methods with the @Subscribe annotation");
else
// 加入缓存
METHOD_CACHE.put(subscriberClass, subscriberMethods);
return subscriberMethods;
注意subscriberMethods.isEmpty()，如果注册了EventBus，但却没有使用注解Subscribe是会出现EventBusException异常的。下面跟进findUsingInfo()方法。
SubscriberMethodFinder#findUsingInfo()
private List<SubscriberMethod> findUsingInfo(Class<?> subscriberClass)
// 从FIND_STATE_POOL数组中查找FindState，命中返回，否则直接new
FindState findState = prepareFindState();
// 初始化FindState
findState.initForSubscriber(subscriberClass);
while (findState.clazz != null)
findState.subscriberInfo = getSubscriberInfo(findState);
// findState.subscriberInfo默认null
if (findState.subscriberInfo != null)
SubscriberMethod[] array = findState.subscriberInfo.getSubscriberMethods();
for (SubscriberMethod subscriberMethod : array)
if (findState.checkAdd(subscriberMethod.method, subscriberMethod.eventType))
findState.subscriberMethods.add(subscriberMethod);
else
findUsingReflectionInSingleClass(findState);
// 将findState.clazz变为改类的父类
findState.moveToSuperclass();
return getMethodsAndRelease(findState);
// SubscriberMethodFinder$FindState#initForSubscriber()
void initForSubscriber(Class<?> subscriberClass)
this.subscriberClass = clazz = subscriberClass;
skipSuperClasses = false;
subscriberInfo = null;
findState.subscriberInfo默认null，那么就进入到findUsingReflectionInSingleClass(findState)，先看下这个方法，等下还要返回来看。
SubscriberMethodFinder#findUsingReflectionInSingleClass()
private static final int MODIFIERS_IGNORE = Modifier.ABSTRACT | Modifier.STATIC | BRIDGE | SYNTHETIC;
private void findUsingReflectionInSingleClass(FindState findState)
Method[] methods;
try
// This is faster than getMethods, especially when subscribers are fat classes like Activities
// 获取到类中所有的方法
methods = findState.clazz.getDeclaredMethods();
catch (Throwable th)
// Workaround for java.lang.NoClassDefFoundError, see https://github.com/greenrobot/EventBus/issues/149
methods = findState.clazz.getMethods();
findState.skipSuperClasses = true;
for (Method method : methods)
// 获取方法的修饰符
int modifiers = method.getModifiers();
// 必须被public修饰，而且不能为MODIFIERS_IGNORE
// MODIFIERS_IGNORE定义为ABSTRACT、STATIC、BRIDGE、SYNTHETIC。
if ((modifiers & Modifier.PUBLIC) != 0 && (modifiers & MODIFIERS_IGNORE) == 0)
// 获取方法所有参数类型
Class<?>[] parameterTypes = method.getParameterTypes();
if (parameterTypes.length == 1)
// 是否有Subscribe注解标签
Subscribe subscribeAnnotation = method.getAnnotation(Subscribe.class);
if (subscribeAnnotation != null)
// 带有Subscribe注解标签的方法的第一个参数类型
Class<?> eventType = parameterTypes[0];
// 关联method, eventType到anyMethodByEventType
if (findState.checkAdd(method, eventType))
ThreadMode threadMode = subscribeAnnotation.threadMode();
// 构造SubscriberMethod，并且添加到findState.subscriberMethods
findState.subscriberMethods.add(new SubscriberMethod(method, eventType, threadMode,
subscribeAnnotation.priority(), subscribeAnnotation.sticky()));
// strictMethodVerification 默认为false，不会抛出异常，但还是建议符合规范
else if (strictMethodVerification && method.isAnnotationPresent(Subscribe.class))
String methodName = method.getDeclaringClass().getName() + "." + method.getName();
throw new EventBusException("@Subscribe method " + methodName +
"must have exactly 1 parameter but has " + parameterTypes.length);
else if (strictMethodVerification && method.isAnnotationPresent(Subscribe.class))
String methodName = method.getDeclaringClass().getName() + "." + method.getName();
throw new EventBusException(methodName +
" is a illegal @Subscribe method: must be public, non-static, and non-abstract");
// `SubscriberMethodFinder#checkAdd()`
boolean checkAdd(Method method, Class<?> eventType)
// 2 level check: 1st level with event type only (fast), 2nd level with complete signature when required.
// Usually a subscriber doesn't have methods listening to the same event type.
Object existing = anyMethodByEventType.put(eventType, method);
if (existing == null)
return true;
else
...
接下来返回SubscriberMethodFinder#findUsingInfo()接着看，在findUsingInfo()中循环执行完后return getMethodsAndRelease(findState)
static class FindState
final List<SubscriberMethod> subscriberMethods = new ArrayList<>();
...
private List<SubscriberMethod> getMethodsAndRelease(FindState findState)
List<SubscriberMethod> subscriberMethods = new ArrayList<>(findState.subscriberMethods);
// 置空findState
findState.recycle();
synchronized (FIND_STATE_POOL)
for (int i = 0; i < POOL_SIZE; i++)
if (FIND_STATE_POOL[i] == null)
FIND_STATE_POOL[i] = findState;
break;
return subscriberMethods;
在getMethodsAndRelease()中将findState置空，存放进FIND_STATE_POOL数组，最后返回findState.subscriberMethods。返回EventBus#register()。
EventBus#register()
public void register(Object subscriber)
Class<?> subscriberClass = subscriber.getClass();
List<SubscriberMethod> subscriberMethods = subscriberMethodFinder.findSubscriberMethods(subscriberClass);
synchronized (this)
for (SubscriberMethod subscriberMethod : subscriberMethods)
subscribe(subscriber, subscriberMethod);
调用SubscriberMethodFinder#findSubscriberMethods()后，以List<SubscriberMethod>形式返回了订阅者所有的订阅事件。然后遍历执行subscribe()方法。看样子应该是遍历List<SubscriberMethod>，然后将订阅者和订阅事件绑定。没撒好说的，跟进subscribe()
EventBus#subscribe()
private void subscribe(Object subscriber, SubscriberMethod subscriberMethod)
// 获取订阅事件的类型，即订阅方法中的唯一参数类型
Class<?> eventType = subscriberMethod.eventType;
// 用订阅者和订阅方法构造一个Subscription对象
Subscription newSubscription = new Subscription(subscriber, subscriberMethod);
// 查找所有的订阅了订阅事件的订阅者
CopyOnWriteArrayList<Subscription> subscriptions = subscriptionsByEventType.get(eventType);
// 没有订阅者订阅过则新建个CopyOnWriteArrayList<subscriptions>，并put进subscriptionsByEventType PS:CopyOnWriteArrayList支持并发读写
if (subscriptions == null)
subscriptions = new CopyOnWriteArrayList<>();
subscriptionsByEventType.put(eventType, subscriptions);
else
// 订阅者List不为空，而且已经包含了newSubscription，则会抛出异常。即：订阅者不能重复订阅同一事件
if (subscriptions.contains(newSubscription))
throw new EventBusException("Subscriber " + subscriber.getClass() + " already registered to event "
+ eventType);
int size = subscriptions.size();
// 根据订阅者优先级，增加到订阅者列表subscriptions的相应位置
for (int i = 0; i <= size; i++)
if (i == size || subscriberMethod.priority > subscriptions.get(i).subscriberMethod.priority)
subscriptions.add(i, newSubscription);
break;
// 获取订阅者所有订阅事件的列表，默认为null
List<Class<?>> subscribedEvents = typesBySubscriber.get(subscriber);
if (subscribedEvents == null)
subscribedEvents = new ArrayList<>();
typesBySubscriber.put(subscriber, subscribedEvents);
// 将订阅事件添加进对应订阅者的订阅列表
subscribedEvents.add(eventType);
// sticky默认为false
if (subscriberMethod.sticky)
if (eventInheritance)
// Existing sticky events of all subclasses of eventType have to be considered.
// Note: Iterating over all events may be inefficient with lots of sticky events,
// thus data structure should be changed to allow a more efficient lookup
// (e.g. an additional map storing sub classes of super classes: Class -> List<Class>).
Set<Map.Entry<Class<?>, Object>> entries = stickyEvents.entrySet();
for (Map.Entry<Class<?>, Object> entry : entries)
Class<?> candidateEventType = entry.getKey();
if (eventType.isAssignableFrom(candidateEventType))
Object stickyEvent = entry.getValue();
checkPostStickyEventToSubscription(newSubscription, stickyEvent);
else
Object stickyEvent = stickyEvents.get(eventType);
checkPostStickyEventToSubscription(newSubscription, stickyEvent);
EventBus#Register()其实只做了三件事：
1. 查找订阅者所有的订阅事件
2. 将订阅事件作为key，所有订阅了此订阅事件的订阅者作为value存放进subscriptionsByEventType
3. 将订阅者作为key，订阅者的所有订阅事件作为value存放进typesBySubscriber
至此，EventBus.getDefault().register(this)流程完毕。
2. Post流程
EventBus#getDefault()
获取EventBus实例。和Register流程中一样，不再赘述。
EventBus#post()
/** Posts the given event to the event bus. */
public void post(Object event)
// 依据不同的线程获取相应的刚初始化的PostingThreadState
PostingThreadState postingState = currentPostingThreadState.get();
List<Object> eventQueue = postingState.eventQueue;
// 将event加入到postingState.eventQueue
eventQueue.add(event);
// isPosting默认false
if (!postingState.isPosting)
// 判断是否是主线程
postingState.isMainThread = Looper.getMainLooper() == Looper.myLooper();
postingState.isPosting = true;
if (postingState.canceled)
throw new EventBusException("Internal error. Abort state was not reset");
try
// 遍历发送eventQueue中的event
while (!eventQueue.isEmpty())
postSingleEvent(eventQueue.remove(0), postingState);
finally
postingState.isPosting = false;
postingState.isMainThread = false;
上面代码中currentPostingThreadState为ThreadLocal<PostingThreadState>对象，对ThreadLocal<>机制不了解的同学，可以查看这篇博客。下面跟进postSingleEvent()方法。
EventBus#postSingleEvent()
private void postSingleEvent(Object event, PostingThreadState postingState) throws Error
// 获取event的类型
Class<?> eventClass = event.getClass();
boolean subscriptionFound = false;
// eventInheritance默认为true
if (eventInheritance)
// 依据订阅事件类型，将订阅事件类型及所有父类添加进eventTypes。详情见下文EventBus.lookupAllEventTypes()分析
List<Class<?>> eventTypes = lookupAllEventTypes(eventClass);
int countTypes = eventTypes.size();
// 遍历countTypes，通过调用postSingleEventForEventType()方法通知所有订阅者
for (int h = 0; h < countTypes; h++)
Class<?> clazz = eventTypes.get(h);
subscriptionFound |= postSingleEventForEventType(event, postingState, clazz);
else
subscriptionFound = postSingleEventForEventType(event, postingState, eventClass);
if (!subscriptionFound)
if (logNoSubscriberMessages)
Log.d(TAG, "No subscribers registered for event " + eventClass);
if (sendNoSubscriberEvent && eventClass != NoSubscriberEvent.class &&
eventClass != SubscriberExceptionEvent.class)
post(new NoSubscriberEvent(this, event));
EventBus#lookupAllEventTypes()
private static List<Class<?>> lookupAllEventTypes(Class<?> eventClass)
synchronized (eventTypesCache)
// 根据订阅事件查找所有自身及父类，eventTypes默认为null
List<Class<?>> eventTypes = eventTypesCache.get(eventClass);
if (eventTypes == null)
eventTypes = new ArrayList<>();
Class<?> clazz = eventClass;
while (clazz != null)
// 将订阅事件添加进eventTypes
eventTypes.add(clazz);
// 遍历订阅事件的所有父类，依次添加进eventTypes
addInterfaces(eventTypes, clazz.getInterfaces());
clazz = clazz.getSuperclass();
// 将订阅事件和包含订阅事件自身及所有父类的eventTypes添加进eventTypesCache
eventTypesCache.put(eventClass, eventTypes);
return eventTypes;
现在假设传递的数据为Person类，而Person类实现了IPerson接口。通过上面的分析可以得出结论：在传递对象（Person）的时候，订阅事件中参数为被传递对象的所有父类订阅事件（IPerson）也都会被调用。笔者已经验证通过，感兴趣的同学可以再验证一下。
EventBus#postSingleEventForEventType()
private boolean postSingleEventForEventType(Object event, PostingThreadState postingState, Class<?> eventClass)
CopyOnWriteArrayList<Subscription> subscriptions;
synchronized (this)
// 根据订阅事件查找所有已经注册过的订阅者
// 注意：这里第一次传递进来的是订阅事件，之后会逐个传递进来订阅事件的父类
subscriptions = subscriptionsByEventType.get(eventClass);
if (subscriptions != null && !subscriptions.isEmpty())
for (Subscription subscription : subscriptions)
postingState.event = event;
postingState.subscription = subscription;
boolean aborted = false;
try
// 参数解释：subscription-被遍历到的订阅者;event-订阅事件参数(子类);
postToSubscription(subscription, event, postingState.isMainThread);
aborted = postingState.canceled;
finally
postingState.event = null;
postingState.subscription = null;
postingState.canceled = false;
if (aborted)
break;
return true;
return false;
在EventBus#register()最后总结道：将订阅事件作为key，所有订阅了此订阅事件的订阅者作为value存放进subscriptionsByEventType。这里就依据订阅事件然后查找对应所有的订阅者。注意：由于遍历订阅事件参数所有父类的原因，一个订阅事件的Post第一次执行postToSubscription()时，subscription参数，遍历时为订阅事件的订阅者。之后再调用postToSubscription()时，subscription参数都为订阅时间父类的订阅者。而event参数则一直是订阅事件中的唯一参数（最底层子类）。
EventBus#postToSubscription()
private void postToSubscription(Subscription subscription, Object event, boolean isMainThread)
switch (subscription.subscriberMethod.threadMode)
case POSTING:
invokeSubscriber(subscription, event);
break;
case MAIN:
if (isMainThread)
invokeSubscriber(subscription, event);
else
mainThreadPoster.enqueue(subscription, event);
break;
case BACKGROUND:
if (isMainThread)
backgroundPoster.enqueue(subscription, event);
else
invokeSubscriber(subscription, event);
break;
case ASYNC:
asyncPoster.enqueue(subscription, event);
break;
default:
throw new IllegalStateException("Unknown thread mode: " + subscription.subscriberMethod.threadMode);
看到这里差不多可以松口气，终于要分发调用订阅者的订阅事件了！写了整整一下午，容我抽支烟再。
首先根据ThreadMode确定分发类型。这里以最常用的Main为例，其余两个Poster同理。如果是isMainThread=true，那么直接调用invokeSubscriber()，否则调用mainThreadPoster.enqueue()。下面分别解释这两种情况。
EventBus#invokeSubscriber()
void invokeSubscriber(Subscription subscription, Object event)
try
// 反射调用
subscription.subscriberMethod.method.invoke(subscription.subscriber, event);
catch (InvocationTargetException e)
handleSubscriberException(subscription, event, e.getCause());
catch (IllegalAccessException e)
throw new IllegalStateException("Unexpected exception", e);
没撒好说的，直接反射调用订阅者的订阅事件。注意：参数event是子类对象，就算调用订阅事件中唯一参数是参数的父类，那么传递的仍然是子类对象。笔者已经验证，感兴趣的同学可以自行验证。然后查看HandlerPoster#enqueue()。
HandlerPoster#enqueue()
final class HandlerPoster extends Handler
...
void enqueue(Subscription subscription, Object event)
// 尝试从pendingPostPool中获取pendingPost，没有则直接new PendingPost
PendingPost pendingPost = PendingPost.obtainPendingPost(subscription, event);
synchronized (this)
// 加入队列
queue.enqueue(pendingPost);
if (!handlerActive)
handlerActive = true;
// 发送空消息 调用handleMessage
if (!sendMessage(obtainMessage()))
throw new EventBusException("Could not send handler message");
@Override
public void handleMessage(Message msg)
// 已经切换到主线程
while (true)
// 遍历获取queue中的PendingPost对象
PendingPost pendingPost = queue.poll();
...
// 调用eventBus.invokeSubscriber
eventBus.invokeSubscriber(pendingPost);
...
EventBus#invokeSubscriber()
void invokeSubscriber(PendingPost pendingPost)
// 提取订阅事件
Object event = pendingPost.event;
// 提取订阅者
Subscription subscription = pendingPost.subscription;
// 释放pendingPost
PendingPost.releasePendingPost(pendingPost);
if (subscription.active)
// 反射调用订阅者的订阅事件
invokeSubscriber(subscription, event);
至此，订阅者在相应线程调用订阅事件完成，EventBus.getDefault().Post()流程完毕。
EventBus#Post()也只做了三件事
1. 根据订阅事件在subscriptionsByEventType中查找相应的订阅者
2. 分发订阅者的订阅事件调用线程
2. 通过反射调用订阅者的订阅事件
3. unregister流程
EventBus#getDefault()
获取EventBus实例。和Register流程中一样，不再赘述。
EventBus#unregister()
public synchronized void unregister(Object subscriber)
List<Class<?>> subscribedTypes = typesBySubscriber.get(subscriber);
if (subscribedTypes != null)
for (Class<?> eventType : subscribedTypes)
unsubscribeByEventType(subscriber, eventType);
typesBySubscriber.remove(subscriber);
else
Log.w(TAG, "Subscriber to unregister was not registered before: " + subscriber.getClass());
EventBus#unsubscribeByEventType()
private void unsubscribeByEventType(Object subscriber, Class<?> eventType)
List<Subscription> subscriptions = subscriptionsByEventType.get(eventType);
if (subscriptions != null)
int size = subscriptions.size();
for (int i = 0; i < size; i++)
Subscription subscription = subscriptions.get(i);
if (subscription.subscriber == subscriber)
subscription.active = false;
subscriptions.remove(i);
i--;
size--;
在EventBus#register()最后总结道：
将订阅事件作为key，所有订阅了此订阅事件的订阅者作为value存放进subscriptionsByEventType。
将订阅者作为key，订阅者的所有订阅事件作为value存放进typesBySubscriber。
现在要反注册咯。移除相应的key、value即可。EventBus3.0的使用及源码解析到此结束，Have a nice day~
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