C# 观察者模式实现
代码：
using System;
using System.Collections.Generic;public delegate void NotificationObserverCallback(object obj);public class NotificationObserver
{public NotificationObserverCallback Selector = null;public string KeyName = "";
}public class NotificationCenter{private static NotificationCenter _instance;private Dictionary<object, List<NotificationObserver>> _allObserversDic;public static NotificationCenter Instance{get { if (_instance == null) { _instance = new NotificationCenter(); } return _instance; }}private NotificationCenter(){_allObserversDic = new Dictionary<object, List<NotificationObserver>>();}private bool ObserverExisted(object target, string name){if (target != null) {if (_allObserversDic.ContainsKey(target)){var lists = _allObserversDic[target];foreach(var item in lists){if (item.KeyName == name){return true;}}}}return false;}public void AddObserver(object target, NotificationObserverCallback selector, string name){if (target != null && name.Length > 0) {if (this.ObserverExisted(target, name) == false){var observer = new NotificationObserver();observer.Selector = selector;observer.KeyName = name;if (_allObserversDic.ContainsKey(target) == false){var lists = new List<NotificationObserver>();lists.Add(observer);_allObserversDic.Add(target, lists);}else{_allObserversDic[target].Add(observer);}}}}public void RemoveObserver(object target, string name){if (_allObserversDic.ContainsKey(target)){var lists = _allObserversDic[target];foreach (var item in lists){if (item.KeyName == name){lists.Remove(item);break;}}if (lists.Count == 0){_allObserversDic.Remove(target);}}}public void RemoveAllObservers(object target){_allObserversDic.Remove(target);}private void TryPostNotification(string name,object obj){foreach (var pair in _allObserversDic){foreach (var item in pair.Value){if (item.KeyName == name) {if (item.Selector != null) {item.Selector(obj);}}}}}public void PostNotification(string name){this.TryPostNotification(name, null);}
}添加监听
public void Init()
{NotificationCenter.Instance.AddObserver(this, TestRespond, "test__");
}private void TestRespond(object obj) {}抛出事件
NotificationCenter.Instance.PostNotification("test__");