eventbus 源码分析
2016-10-17 13:07:01 0 举报AI智能生成
EventBus 是一个 Android 事件发布/订阅框架，通过解耦发布者和订阅者，简化了应用内部的组件通信。源码分析显示，EventBus 主要包含四个部分：粘性事件、线程池、优先级队列和反射。粘性事件用于在事件处理过程中保持上下文信息；线程池用于并发处理事件；优先级队列用于对事件进行排序；反射则用于实现动态注册和解注册。EventBus 的实现原理是基于观察者模式，通过发布事件和订阅事件来实现组件之间的通信。
作者其他创作
大纲/内容
findUsingInfo
FindState findState = prepareFindState();
synchronized (FIND_STATE_POOL) {
for (int i = 0; i < POOL_SIZE; i++) {
FindState state = FIND_STATE_POOL[i];
if (state != null) {
FIND_STATE_POOL[i] = null;
return state;
}
}
}
在FIND_STATE_POOL中取出FindState;
return new FindState();
若FIND_STATE_POOL所有元素都空，则返回new FindState()
findState.initForSubscriber(subscriberClass);
this.subscriberClass = clazz = subscriberClass;
skipSuperClasses = false;
subscriberInfo = null;
while (findState.clazz != null) {
findState.subscriberInfo = getSubscriberInfo(findState);
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);
}
findState.moveToSuperclass();
}
private SubscriberInfo getSubscriberInfo(FindState findState) {
if (findState.subscriberInfo != null && findState.subscriberInfo.getSuperSubscriberInfo() != null) {
SubscriberInfo superclassInfo = findState.subscriberInfo.getSuperSubscriberInfo();
if (findState.clazz == superclassInfo.getSubscriberClass()) {
return superclassInfo;
}
}
if (subscriberInfoIndexes != null) {
for (SubscriberInfoIndex index : subscriberInfoIndexes) {
SubscriberInfo info = index.getSubscriberInfo(findState.clazz);
if (info != null) {
return info;
}
}
}
return null;
}
如果父类有SubscriberInfo和当前subsrciberInfo一样返回父类的
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 {
if (existing instanceof Method) {
if (!checkAddWithMethodSignature((Method) existing, eventType)) {
// Paranoia check
throw new IllegalStateException();
}
// Put any non-Method object to "consume" the existing Method
anyMethodByEventType.put(eventType, this);
}
return checkAddWithMethodSignature(method, eventType);
}
}
private boolean checkAddWithMethodSignature(Method method, Class eventType) {
methodKeyBuilder.setLength(0);
methodKeyBuilder.append(method.getName());
methodKeyBuilder.append('>').append(eventType.getName());
String methodKey = methodKeyBuilder.toString();
Class methodClass = method.getDeclaringClass();
Class methodClassOld = subscriberClassByMethodKey.put(methodKey, methodClass);
if (methodClassOld == null || methodClassOld.isAssignableFrom(methodClass)) {
// Only add if not already found in a sub class
return true;
} else {
// Revert the put, old class is further down the class hierarchy
subscriberClassByMethodKey.put(methodKey, methodClassOld);
return false;
}
}
getMethodsAndRelease(findState)
0 条评论
下一页
