详解CocosCreator消息分发机制

/**
 * 消息监听回调方法
 */
export type NotifyListener = (src: any, data: any) => void;

private static msg2listDict: Dictionary< string, Array<NotifyListenerInfo> > = new Dictionary< string, Array<NotifyListenerInfo> >();

/**
 * 添加多次监听者，需要手动移除
 * @param msg
 * @param listener
 * @param target
 */
public static addListener(msg: string, listener: NotifyListener, target?: any): void {}
 
/**
 * 添加单次监听者，事件触发后即移除
 * @param msg
 * @param listener
 * @param target
 */
public static addOnceListener(msg: string, listener: NotifyListener, target?: any): void {}
 
/**
 * 移除指定消息指定的监听者
 * @param msg
 * @param listener
 */
public static removeMsgListener(msg: string, listener: NotifyListener): void {}
 
/**
 * 移除指定消息所有监听者
 * @param msg
 */
public static removeMsgAllListeners(msg: string): void {}
 
/**
 * 移除指定目标对指定消息的监听
 * @param msg
 * @param target
 */
public static removeTargetMsgListen(msg: string, target: any): void {}
 
/**
 * 移除指定目标所有消息监听
 * @param target
 */
public static removeTargetAllMsgListen(target: any): void {}
 
/**
 * 派发消息
 * @param msg
 * @param src
 * @param data
 */
public static notify(msg: string, src: any, data: any): void {}

private static listener2add: Array<NotifyListenerInfo> = [];

// 该消息正在派发，放入待添加队列
if (NotifyCenter.notifyMsgs.indexOf(msg) >= 0) {
    NotifyCenter.listener2add.push(info);
    return;
}

private static listener2remove: Array<NotifyListenerInfo> = [];

// 该消息正在派发，放入待移除队列
if (NotifyCenter.notifyMsgs.indexOf(msg) >= 0) {
    NotifyCenter.listener2remove.push(list[i]);
} else {
    list.splice(i, 1);
}

// 队列不存在，不需要处理
let list = NotifyCenter.msg2listDict.get(msg);
if (!list) {
    return;
}
 
// 标记消息正在派发，多个消息可能同时在派发，同一消息可能标记多次
NotifyCenter.notifyMsgs.push(msg);
 
// 处理消息派发
for (let i = 0, n = list.length; i < n; i++) {
    NotifyCenter._dispatch(list[i], src, data, false);
}

// 在移除队列，不派发
if (NotifyCenter.listener2remove.indexOf(info) >= 0) {
    return;
}

// 处理待添加队列派发
for (let i = 0, n = msg2add.length; i < n; i++) {
    if (listener2add[i].msg == msg) {
        NotifyCenter._dispatch(listener2add[i], src, data, true);
    }
}