Unity3D之通过C#使用Advanced CSharp Messenger

Advanced CSharp Messenger 属于C#事件的一种。 维基百科中由详细的说明http://wiki.unity3d.com/index.php?title=Advanced_CSharp_Messenger

Advanced CSharp Messenger的特点可以将游戏对象做为参数发送。到底Advanced CSharp Messenger有什么用呢？先创建一个立方体对象，然后把Script脚本绑定在这个对象中。脚本中有一个方法叫DoSomething()。写一段简单的代码，通常我们在调用方法的时候需要这样来写。

 private Script script;
 void Awake()
 {
     GameObject cube = GameObject.Find("Cube");
     script = cube.GetComponent<Script>();
 }

 void Update()
 {
     if(Input.GetMouseButtonDown())
     {
         script.DoSomething();
     }
 }

代码比较简单，我就不注释了。 原理就是先获取游戏对象，接着获取脚本组件对象，最后通过脚本组件对象去调用对应脚本中的方法，这样的调用方法我们称之为直接调用。

这个例子中我只调用了一个对象的方法，如果说有成千上万个对象，那么这样调用是不是感觉自己的代码非常的丑？因为你需要一个一个的获取对象然后获取脚本组件然后在调用方法。。。。。 （想想都恐怖！！）

下面我们在用Advanced CSharp Messenger来实现事件的调用。按照维基百科中首先把Message.cs 和Callback.cs拷贝在你的工程中。

CallBack.cs

 public delegate void Callback();
 public delegate void Callback<T>(T arg1);
 public delegate void Callback<T, U>(T arg1, U arg2);
 public delegate void Callback<T, U, V>(T arg1, U arg2, V arg3);

 Message.cs

 /*
  * Advanced C# messenger by Ilya Suzdalnitski. V1.0
  *
  * Based on Rod Hyde's "CSharpMessenger" and Magnus Wolffelt's "CSharpMessenger Extended".
  *
  * Features:
      * Prevents a MissingReferenceException because of a reference to a destroyed message handler.
      * Option to log all messages
      * Extensive error detection, preventing silent bugs
  *
  * Usage examples:
      1. Messenger.AddListener<GameObject>("prop collected", PropCollected);
         Messenger.Broadcast<GameObject>("prop collected", prop);
      2. Messenger.AddListener<float>("speed changed", SpeedChanged);
         Messenger.Broadcast<float>("speed changed", 0.5f);
  *
  * Messenger cleans up its evenTable automatically upon loading of a new level.
  *
  * Don't forget that the messages that should survive the cleanup, should be marked with Messenger.MarkAsPermanent(string)
  *
  */

 //#define LOG_ALL_MESSAGES
 //#define LOG_ADD_LISTENER
 //#define LOG_BROADCAST_MESSAGE
 #define REQUIRE_LISTENER

 using System;
 using System.Collections.Generic;
 using UnityEngine;

 static internal class Messenger {
     #region Internal variables

     //Disable the unused variable warning
 #pragma warning disable 0414
     //Ensures that the MessengerHelper will be created automatically upon start of the game.
     static private MessengerHelper messengerHelper = ( new GameObject("MessengerHelper") ).AddComponent< MessengerHelper >();
 #pragma warning restore 0414

     static public Dictionary<string, Delegate> eventTable = new Dictionary<string, Delegate>();

     //Message handlers that should never be removed, regardless of calling Cleanup
     static public List< string > permanentMessages = new List< string > ();
     #endregion
     #region Helper methods
     //Marks a certain message as permanent.
     static public void MarkAsPermanent(string eventType) {
 #if LOG_ALL_MESSAGES
         Debug.Log("Messenger MarkAsPermanent \t\"" + eventType + "\"");
 #endif

         permanentMessages.Add( eventType );
     }

     static public void Cleanup()
     {
 #if LOG_ALL_MESSAGES
         Debug.Log("MESSENGER Cleanup. Make sure that none of necessary listeners are removed.");
 #endif

         List< string > messagesToRemove = new List<string>();

         foreach (KeyValuePair<string, Delegate> pair in eventTable) {
             bool wasFound = false;

             foreach (string message in permanentMessages) {
                 if (pair.Key == message) {
                     wasFound = true;
                     break;
                 }
             }

             if (!wasFound)
                 messagesToRemove.Add( pair.Key );
         }

         foreach (string message in messagesToRemove) {
             eventTable.Remove( message );
         }
     }

     static public void PrintEventTable()
     {
         Debug.Log("\t\t\t=== MESSENGER PrintEventTable ===");

         foreach (KeyValuePair<string, Delegate> pair in eventTable) {
             Debug.Log("\t\t\t" + pair.Key + "\t\t" + pair.Value);
         }

         Debug.Log("\n");
     }
     #endregion

     #region Message logging and exception throwing
     static public void OnListenerAdding(string eventType, Delegate listenerBeingAdded) {
 #if LOG_ALL_MESSAGES || LOG_ADD_LISTENER
         Debug.Log("MESSENGER OnListenerAdding \t\"" + eventType + "\"\t{" + listenerBeingAdded.Target + " -> " + listenerBeingAdded.Method + "}");
 #endif

         if (!eventTable.ContainsKey(eventType)) {
             eventTable.Add(eventType, null );
         }

         Delegate d = eventTable[eventType];
         if (d != null && d.GetType() != listenerBeingAdded.GetType()) {
             throw new ListenerException(string.Format("Attempting to add listener with inconsistent signature for event type {0}. Current listeners have type {1} and listener being added has type {2}", eventType, d.GetType().Name, listenerBeingAdded.GetType().Name));
         }
     }

     static public void OnListenerRemoving(string eventType, Delegate listenerBeingRemoved) {
 #if LOG_ALL_MESSAGES
         Debug.Log("MESSENGER OnListenerRemoving \t\"" + eventType + "\"\t{" + listenerBeingRemoved.Target + " -> " + listenerBeingRemoved.Method + "}");
 #endif

         if (eventTable.ContainsKey(eventType)) {
             Delegate d = eventTable[eventType];

             if (d == null) {
                 throw new ListenerException(string.Format("Attempting to remove listener with for event type \"{0}\" but current listener is null.", eventType));
             } else if (d.GetType() != listenerBeingRemoved.GetType()) {
                 throw new ListenerException(string.Format("Attempting to remove listener with inconsistent signature for event type {0}. Current listeners have type {1} and listener being removed has type {2}", eventType, d.GetType().Name, listenerBeingRemoved.GetType().Name));
             }
         } else {
             throw new ListenerException(string.Format("Attempting to remove listener for type \"{0}\" but Messenger doesn't know about this event type.", eventType));
         }
     }

     static public void OnListenerRemoved(string eventType) {
         if (eventTable[eventType] == null) {
             eventTable.Remove(eventType);
         }
     }

     static public void OnBroadcasting(string eventType) {
 #if REQUIRE_LISTENER
         if (!eventTable.ContainsKey(eventType)) {
             throw new BroadcastException(string.Format("Broadcasting message \"{0}\" but no listener found. Try marking the message with Messenger.MarkAsPermanent.", eventType));
         }
 #endif
     }

     static public BroadcastException CreateBroadcastSignatureException(string eventType) {
         return new BroadcastException(string.Format("Broadcasting message \"{0}\" but listeners have a different signature than the broadcaster.", eventType));
     }

     public class BroadcastException : Exception {
         public BroadcastException(string msg)
             : base(msg) {
         }
     }

     public class ListenerException : Exception {
         public ListenerException(string msg)
             : base(msg) {
         }
     }
     #endregion

     #region AddListener
     //No parameters
     static public void AddListener(string eventType, Callback handler) {
         OnListenerAdding(eventType, handler);
         eventTable[eventType] = (Callback)eventTable[eventType] + handler;
     }

     //Single parameter
     static public void AddListener<T>(string eventType, Callback<T> handler) {
         OnListenerAdding(eventType, handler);
         eventTable[eventType] = (Callback<T>)eventTable[eventType] + handler;
     }

     //Two parameters
     static public void AddListener<T, U>(string eventType, Callback<T, U> handler) {
         OnListenerAdding(eventType, handler);
         eventTable[eventType] = (Callback<T, U>)eventTable[eventType] + handler;
     }

     //Three parameters
     static public void AddListener<T, U, V>(string eventType, Callback<T, U, V> handler) {
         OnListenerAdding(eventType, handler);
         eventTable[eventType] = (Callback<T, U, V>)eventTable[eventType] + handler;
     }
     #endregion

     #region RemoveListener
     //No parameters
     static public void RemoveListener(string eventType, Callback handler) {
         OnListenerRemoving(eventType, handler);
         eventTable[eventType] = (Callback)eventTable[eventType] - handler;
         OnListenerRemoved(eventType);
     }

     //Single parameter
     static public void RemoveListener<T>(string eventType, Callback<T> handler) {
         OnListenerRemoving(eventType, handler);
         eventTable[eventType] = (Callback<T>)eventTable[eventType] - handler;
         OnListenerRemoved(eventType);
     }

     //Two parameters
     static public void RemoveListener<T, U>(string eventType, Callback<T, U> handler) {
         OnListenerRemoving(eventType, handler);
         eventTable[eventType] = (Callback<T, U>)eventTable[eventType] - handler;
         OnListenerRemoved(eventType);
     }

     //Three parameters
     static public void RemoveListener<T, U, V>(string eventType, Callback<T, U, V> handler) {
         OnListenerRemoving(eventType, handler);
         eventTable[eventType] = (Callback<T, U, V>)eventTable[eventType] - handler;
         OnListenerRemoved(eventType);
     }
     #endregion

     #region Broadcast
     //No parameters
     static public void Broadcast(string eventType) {
 #if LOG_ALL_MESSAGES || LOG_BROADCAST_MESSAGE
         Debug.Log("MESSENGER\t" + System.DateTime.Now.ToString("hh:mm:ss.fff") + "\t\t\tInvoking \t\"" + eventType + "\"");
 #endif
         OnBroadcasting(eventType);

         Delegate d;
         if (eventTable.TryGetValue(eventType, out d)) {
             Callback callback = d as Callback;

             if (callback != null) {
                 callback();
             } else {
                 throw CreateBroadcastSignatureException(eventType);
             }
         }
     }

     //Single parameter
     static public void Broadcast<T>(string eventType, T arg1) {
 #if LOG_ALL_MESSAGES || LOG_BROADCAST_MESSAGE
         Debug.Log("MESSENGER\t" + System.DateTime.Now.ToString("hh:mm:ss.fff") + "\t\t\tInvoking \t\"" + eventType + "\"");
 #endif
         OnBroadcasting(eventType);

         Delegate d;
         if (eventTable.TryGetValue(eventType, out d)) {
             Callback<T> callback = d as Callback<T>;

             if (callback != null) {
                 callback(arg1);
             } else {
                 throw CreateBroadcastSignatureException(eventType);
             }
         }
     }

     //Two parameters
     static public void Broadcast<T, U>(string eventType, T arg1, U arg2) {
 #if LOG_ALL_MESSAGES || LOG_BROADCAST_MESSAGE
         Debug.Log("MESSENGER\t" + System.DateTime.Now.ToString("hh:mm:ss.fff") + "\t\t\tInvoking \t\"" + eventType + "\"");
 #endif
         OnBroadcasting(eventType);

         Delegate d;
         if (eventTable.TryGetValue(eventType, out d)) {
             Callback<T, U> callback = d as Callback<T, U>;

             if (callback != null) {
                 callback(arg1, arg2);
             } else {
                 throw CreateBroadcastSignatureException(eventType);
             }
         }
     }

     //Three parameters
     static public void Broadcast<T, U, V>(string eventType, T arg1, U arg2, V arg3) {
 #if LOG_ALL_MESSAGES || LOG_BROADCAST_MESSAGE
         Debug.Log("MESSENGER\t" + System.DateTime.Now.ToString("hh:mm:ss.fff") + "\t\t\tInvoking \t\"" + eventType + "\"");
 #endif
         OnBroadcasting(eventType);

         Delegate d;
         if (eventTable.TryGetValue(eventType, out d)) {
             Callback<T, U, V> callback = d as Callback<T, U, V>;

             if (callback != null) {
                 callback(arg1, arg2, arg3);
             } else {
                 throw CreateBroadcastSignatureException(eventType);
             }
         }
     }
     #endregion
 }

 //This manager will ensure that the messenger's eventTable will be cleaned up upon loading of a new level.
 public sealed class MessengerHelper : MonoBehaviour {
     void Awake ()
     {
         DontDestroyOnLoad(gameObject);
     }

     //Clean up eventTable every time a new level loads.
     public void OnDisable() {
         Messenger.Cleanup();
     }
 }

然后就可以开始使用了，Messager.Broadcast()这样就好比我们发送了一条广播。

     void Update()
     {
         if(Input.GetMouseButtonDown())
         {
             Messenger.Broadcast("Send");
         }
     }

在需要这条广播的类中来接受它，同样是刚刚说的Script类。接受广播的标志是 Messager.AddListener()参数1表示广播的名称，参数2表示广播所调用的方法。

 using UnityEngine;
 using System.Collections;

 public class Script : MonoBehaviour {

     void Awake()
     {
         Messenger.AddListener( "Send", DoSomething );
     }
     public void DoSomething()
     {
         Debug.Log("DoSomething");
     }
 }

这样一来，只要发送名称为”Send”的方法，就可以在别的类中接收它了。

我们在说说如何通过广播来传递参数,这也是那天那个哥们主要问我的问题。（其实是维基百科上写的不是特别特别的清楚，那哥们误解了）在Callback中可以看出参数最多可以是三个，参数的类型是任意类型，也就是说我们不仅能传递 int float bool 还能传递gameObject类型。

如下所示，发送广播的时候传递了两个参数，参数1是一个游戏对象，参数2是一个int数值。

     void Update()
     {
         if(Input.GetMouseButtonDown())
         {
             GameObject cube = GameObject.Find("Cube");
             Messenger.Broadcast<GameObject,int>("Send",cube,);
         }
     }

然后是接受的地方 参数用<>存在一起。游戏对象也可以完美的传递。

 using UnityEngine;
 using System.Collections;

 public class Script : MonoBehaviour {

     void Awake()
     {
         Messenger.AddListener<GameObject,int>( "Send", DoSomething );
     }
     public void DoSomething(GameObject obj,int i)
     {
         Debug.Log("name " + obj.name + " id =" + i);
     }
 }

如果传递一个参数<T>

两个参数<T,T>

三个参数<T,T,T>   

怎么样使用起来还是挺简单的吧？

我觉得项目中最好不要大量的使用代理事件这类的方法（根据需求而定），虽然可以让你的代码非常的简洁，但是它的效率不高大概比直接调用慢5-倍左右吧，就好比美好的东西一定都有瑕疵一样。 还记得Unity自身也提供了一种发送消息的方法吗？，用过的都知道效率也非常低下，虽然我们看不到它具体实现的源码是如何实现的，但是我觉得原理可能也是这样的。 欢迎和大家一起讨论与学习。