【第四篇】androidEventbus源代码阅读和分析

public static EventBus getDefault() {
        if (sDefaultBus == null) {
            synchronized (EventBus.class) {
                if (sDefaultBus == null) {
                    sDefaultBus = new EventBus();
                }
            }
        }
        return sDefaultBus;
    }

1 public void register(Object subscriber) {
2         if (subscriber == null) {
3             return;
4         }
5         synchronized (this) {
6             mMethodHunter.findSubcribeMethods(subscriber);
7         }
8     }

1 /**
2 * the subscriber method hunter, find all of the subscriber‘s methods
3 * annotated with @Subcriber
4 */
5 SubsciberMethodHunter mMethodHunter =newSubsciberMethodHunter(mSubcriberMap);

 1 public void findSubcribeMethods(Object subscriber) {
 2         if (mSubcriberMap == null) {
 3             throw new NullPointerException("the mSubcriberMap is null. ");
 4         }
 5         Class<?> clazz = subscriber.getClass();
 6         // 查找类中符合要求的注册方法,直到Object类
 7         while (clazz != null && !isSystemCalss(clazz.getName())) {
 8             final Method[] allMethods = clazz.getDeclaredMethods();
 9             for (int i = 0; i < allMethods.length; i++) {
10                 Method method = allMethods[i];
11                 // 根据注解来解析函数
12                 Subscriber annotation = method.getAnnotation(Subscriber.class);
13                 if (annotation != null) {
14                     // 获取方法参数
15                     Class<?>[] paramsTypeClass = method.getParameterTypes();
16                     // 订阅函数只支持一个参数
17                     if (paramsTypeClass != null && paramsTypeClass.length == 1) {
18                         Class<?> paramType = convertType(paramsTypeClass[0]);
19                         EventType eventType = new EventType(paramType, annotation.tag());
20                         TargetMethod subscribeMethod = new TargetMethod(method, eventType,
21                                 annotation.mode());
22                         subscibe(eventType, subscribeMethod, subscriber);
23                     }
24                 }
25             } // end for
26               // 获取父类,以继续查找父类中符合要求的方法
27             clazz = clazz.getSuperclass();
28         }
29     }

/**
     * the event bus‘s subscriber‘s map
     */
    Map<EventType, CopyOnWriteArrayList<Subscription>> mSubcriberMap;

 1 /**
 2      * 按照EventType存储订阅者列表,这里的EventType就是事件类型,一个事件对应0到多个订阅者.
 3      * 
 4      * @param event 事件
 5      * @param method 订阅方法对象
 6      * @param subscriber 订阅者
 7      */
 8     private void subscibe(EventType event, TargetMethod method, Object subscriber) {
 9         CopyOnWriteArrayList<Subscription> subscriptionLists = mSubcriberMap.get(event);
10         if (subscriptionLists == null) {
11             subscriptionLists = new CopyOnWriteArrayList<Subscription>();
12         }
13         Subscription newSubscription = new Subscription(subscriber, method);
14         if (subscriptionLists.contains(newSubscription)) {
15             return;
16         }
17         subscriptionLists.add(newSubscription);
18         // 将事件类型key和订阅者信息存储到map中
19         mSubcriberMap.put(event, subscriptionLists);
20     }