unity 观察者模式应用(事件的广播和监听系统)

首先，分别新建以下三个脚本 脚本1，脚本名：CallBack

//定义了具有不同参数数量的委托类型，提供给EventCenter使用 public delegate void CallBack(); public delegate void CallBack<T>(T arg); public delegate void CallBack<T, X>(T arg1, X arg2); public delegate void CallBack<T, X, Y>(T arg1, X arg2, Y arg3); public delegate void CallBack<T, X, Y, Z>(T arg1, X arg2, Y arg3, Z arg4); public delegate void CallBack<T, X, Y, Z, W>(T arg1, X arg2, Y arg3, Z arg4, W arg5); 

脚本名2：EventType

public enum EventType { //定义枚举，为EventCenter提供事件类型 ShowText, } 

脚本名3：EventCenter

using System; using System.Collections; using System.Collections.Generic; using UnityEngine; public class EventCenter { private static Dictionary<EventType, Delegate> m_EventTable = new Dictionary<EventType, Delegate>(); //添加监听 private static void OnListenerAdding(EventType eventType,Delegate callBack) { if (!m_EventTable.ContainsKey(eventType)) { m_EventTable.Add(eventType, null); } Delegate d = m_EventTable[eventType]; if (d != null && d.GetType() != callBack.GetType()) { throw new Exception(string.Format("尝试为事件{0}添加不同类型的委托，当前事件所对应的委托是{1},要添加的委托类型为{2}", eventType, d.GetType(), callBack.GetType())); } } //移除监听 private static void OnListenerRemoving(EventType eventType,Delegate callBack) { if (m_EventTable.ContainsKey(eventType)) { Delegate d = m_EventTable[eventType]; if (d == null) { throw new Exception(string.Format("移除监听错误：事件{0}没有对应的委托", eventType)); } else if (d.GetType() != callBack.GetType()) { throw new Exception(string.Format("移除监听错误：尝试为事件{0}移除不同类型的委托，当前委托类型为{1},要移除的类型为{2}", eventType, d.GetType(), callBack.GetType())); } } else { throw new Exception(string.Format("移除监听错误：没有事件码{0}", eventType)); } } //移除监听后，刷新监听事件列表 public static void OnListenerRemoeved(EventType eventType) { if (m_EventTable[eventType] == null) { m_EventTable.Remove(eventType); } } //六种参数数量的添加监听方法 //no parameters没有参数 public static void AddListener(EventType eventType,CallBack callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack)m_EventTable[eventType] + callBack; } //Single parametener一个参数 public static void AddListener<T>(EventType eventType, CallBack<T> callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack<T>)m_EventTable[eventType] + callBack; } //two parametener两个参数 public static void AddListener<T,X>(EventType eventType, CallBack<T,X> callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack<T,X>)m_EventTable[eventType] + callBack; } //three parametener三个参数 public static void AddListener<T, X, Y>(EventType eventType, CallBack<T, X, Y> callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y>)m_EventTable[eventType] + callBack; } //four parametener四个参数 public static void AddListener<T, X, Y, Z>(EventType eventType, CallBack<T, X, Y, Z> callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y, Z>)m_EventTable[eventType] + callBack; } //five parametener五个参数 public static void AddListener<T, X, Y, Z, W>(EventType eventType, CallBack<T, X, Y, Z, W> callBack) { OnListenerAdding(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y, Z, W>)m_EventTable[eventType] + callBack; } //六种参数数量情况下的事件移除方法 //no parameters public static void RemoveListener(EventType eventType,CallBack callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //Single parameters public static void RemoveListener<T>(EventType eventType, CallBack<T> callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack<T>)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //two parameters public static void RemoveListener<T,X>(EventType eventType, CallBack<T,X> callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack<T,X>)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //three parameters public static void RemoveListener<T, X, Y>(EventType eventType, CallBack<T, X, Y> callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y>)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //four parameters public static void RemoveListener<T, X, Y, Z>(EventType eventType, CallBack<T, X, Y, Z> callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y, Z>)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //five parameters public static void RemoveListener<T, X, Y, Z, W>(EventType eventType, CallBack<T, X, Y, Z, W> callBack) { OnListenerRemoving(eventType, callBack); m_EventTable[eventType] = (CallBack<T, X, Y, Z, W>)m_EventTable[eventType] - callBack; OnListenerRemoeved(eventType); } //六种参数数量情况下的广播方法 //no parameters public static void Broadcast(EventType eventType) { Delegate d; if (m_EventTable.TryGetValue(eventType,out d)) { CallBack callBack = d as CallBack; if (callBack != null) { callBack(); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型",eventType)); } } } //Single parameters public static void Broadcast<T>(EventType eventType,T arg) { Delegate d; if (m_EventTable.TryGetValue(eventType, out d)) { CallBack<T> callBack = d as CallBack<T>; if (callBack != null) { callBack(arg); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型", eventType)); } } } //two parameters public static void Broadcast<T,X>(EventType eventType, T arg1,X arg2) { Delegate d; if (m_EventTable.TryGetValue(eventType, out d)) { CallBack<T, X> callBack = d as CallBack<T, X>; if (callBack != null) { callBack(arg1,arg2); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型", eventType)); } } } //three parameters public static void Broadcast<T, X, Y>(EventType eventType, T arg1, X arg2, Y arg3) { Delegate d; if (m_EventTable.TryGetValue(eventType, out d)) { CallBack<T, X, Y> callBack = d as CallBack<T, X, Y>; if (callBack != null) { callBack(arg1, arg2, arg3); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型", eventType)); } } } //four parameters public static void Broadcast<T, X, Y, Z>(EventType eventType, T arg1, X arg2, Y arg3, Z arg4) { Delegate d; if (m_EventTable.TryGetValue(eventType, out d)) { CallBack<T, X, Y, Z> callBack = d as CallBack<T, X, Y, Z>; if (callBack != null) { callBack(arg1, arg2, arg3, arg4); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型", eventType)); } } } //five parameters public static void Broadcast<T, X, Y, Z, W>(EventType eventType, T arg1, X arg2, Y arg3, Z arg4, W arg5) { Delegate d; if (m_EventTable.TryGetValue(eventType, out d)) { CallBack<T, X, Y, Z, W> callBack = d as CallBack<T, X, Y, Z, W>; if (callBack != null) { callBack(arg1, arg2, arg3, arg4, arg5); } else { throw new Exception(string.Format("广播事件错误：事件{0}对应委托具有不同的类型", eventType)); } } } } 

场景中新建button，添加一个脚本：

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI; public class BtnClick : MonoBehaviour { private void Awake() { GetComponent<Button>().onClick.AddListener(() => { //按下按钮，发送广播 EventCenter.Broadcast(EventType.ShowText,"你好","吗",3.0F,6,5); }); } } 

场景中新建一个text，添加一个脚本：

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI; public class ShowText : MonoBehaviour { private void Awake() { gameObject.SetActive(false); //添加广播监听，并绑定事件方法为Show EventCenter.AddListener<string,string,float,int,int>(EventType.ShowText, Show); } private void OnDestroy() { //移除广播监听 EventCenter.RemoveListener<string, string, float, int, int>(EventType.ShowText, Show); } public void Show(string str, string str1, float a, int b, int c) { gameObject.SetActive(true); GetComponent<Text>().text = str + str1 + a + b + c; } } 

脚本准备完毕， 把text多复制几份像下图这样 运行场景，点击button，你会发现，BtnClick脚本里发送的广播消息，被显示在了text上，然而button和text之间并没有直接的相互干预(所有的Text上只要挂了脚本“ShowText ”，就都能同一时间接收到btnClick中发送的消息)，这就是观察者模式的作用了。 观察者模式的好处就是，避免了在脚本组件上拖拽物体的方式，降低了代码耦合度。在CallBack中我们定义了CallBack的多个重写，是为了应对不同参数数量的情况。

注意事项：在我们需要更改消息参数数量的时候需要同步在发送时（BtnClick中）、接收时（ShowText中）的参数数量，然后如果CallBack脚本中没有你想使用的委托类型你需要新增，EventCenter脚本中也要添加对应的事件“添加、删除、广播”三种方法

参考视频：http://www.sikiedu.com/my/course/304