Unity 游戏框架搭建 2019 (四十八) MonoBehaviourSimplify 中的消息策略完善

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在上一篇，笔者说，MonoBehaviourSimplify 中的消息策略还有一些小问题。我们在这篇试着解决一下。

先贴出来代码:

using System;
using System.Collections.Generic;namespace QFramework
{public abstract partial class MonoBehaviourSimplify{Dictionary<string, Action<object>> mMsgRegisterRecorder = new Dictionary<string, Action<object>>();protected void RegisterMsg(string msgName, Action<object> onMsgReceived){MsgDispatcher.Register(msgName, onMsgReceived);mMsgRegisterRecorder.Add(msgName, onMsgReceived);}private void OnDestroy(){OnBeforeDestroy();foreach (var keyValuePair in mMsgRegisterRecorder){MsgDispatcher.UnRegister(keyValuePair.Key,keyValuePair.Value);                }mMsgRegisterRecorder.Clear();}protected abstract void OnBeforeDestroy();}public class B : MonoBehaviourSimplify{private void Awake(){RegisterMsg("Do", DoSomething);RegisterMsg("DO1", _ => { });RegisterMsg("DO2", _ => { });RegisterMsg("DO3", _ => { });}void DoSomething(object data){// do something}protected override void OnBeforeDestroy(){}}
}

我们是使用字典进行注册消息的记录的，使用字典就要保证字典中的 key 是唯一的。而我们很可能在一个脚本中对一个关键字注册多次，这样用字典这个数据结构就显得不合理了。

相比字典，List 更合适，因为我们有有可能有重复的内容，而字典更适合做一些查询工作，但是 List 并不支持键值对，怎么办呢？

我们只好创建一个结构来存储我们的消息名和对应的委托，这个结构是一个类叫做 MsgRecord

消息策略部分的代码如下:

    public abstract partial class MonoBehaviourSimplify{List<MsgRecord> mMsgRecorder = new List<MsgRecord>();private class MsgRecord{public string Name;public Action<object> OnMsgReceived;}protected void RegisterMsg(string msgName, Action<object> onMsgReceived){MsgDispatcher.Register(msgName, onMsgReceived);mMsgRecorder.Add(new MsgRecord{Name = msgName,OnMsgReceived = onMsgReceived});}private void OnDestroy(){OnBeforeDestroy();foreach (var msgRecord in mMsgRecorder){MsgDispatcher.UnRegister(msgRecord.Name,msgRecord.OnMsgReceived);                }mMsgRecorder.Clear();}protected abstract void OnBeforeDestroy();}

代码比较简单。

而我们的示例代码，如下，增加了一行重复注册的代码。

    public class B : MonoBehaviourSimplify{private void Awake(){RegisterMsg("Do", DoSomething);RegisterMsg("Do", DoSomething);RegisterMsg("DO1", _ => { });RegisterMsg("DO2", _ => { });RegisterMsg("DO3", _ => { });}void DoSomething(object data){// do something}protected override void OnBeforeDestroy(){}}

而我们的 MonoBehaviourSimplify 内部实现发生了天翻地覆的变化，也没有对我们的示例代码产生一点影响，这叫封装。

那么到这里，我们的消息策略还有问题吗？

还有的，问题在创建 MsgRecord 的部分。
如下:

mMsgRecorder.Add(new MsgRecord
{Name = msgName,OnMsgReceived = onMsgReceived
});

我们每次注册消息，都要 new 一个 MsgRecord 对象出来，而我们在注销的时候，对这个对象是什么都没有做的，注销的代码如下:

foreach (var msgRecord in mMsgRecorder)
{MsgDispatcher.UnRegister(msgRecord.Name,msgRecord.OnMsgReceived);                
}

这样会造成一个性能问题，这个性能问题主要是有 new 时候寻址造成的，具体原因自行搜索，当然在本专栏的后边还是会介绍的。我们要做的，就是减少 new 的发生次数，要想减少，就得让我们的 MsgRecord 能够回收利用。

如何回收利用呢，答案是维护一个容器，比如 List 或者 Queue、Stack 等，也就是传说中的对象池。由于我们的 MsgRecord 的作用仅仅是作为一个存储结构而已，而存储的顺序也不是很重要，所以我们就用做简单的 Stack 结构，也就是栈，来作为 MsgRecord 对象池的容器。

其实现如下:

private class MsgRecord
{static Stack<MsgRecord> mMsgRecordPool = new Stack<MsgRecord>();public static MsgRecord Allocate(){if (mMsgRecordPool.Count > 0){return mMsgRecordPool.Pop();}return new MsgRecord();}public void Recycle(){Name = null;OnMsgReceived = null;mMsgRecordPool.Push(this);}public string Name;public Action<object> OnMsgReceived;
}

由于这个对象池只给 MsgRecord 用，所以就在 MsgRecord 内部实现了。
Allocate 是申请，也就是获取对象。Recycle 就是回收，当不用的时候调用一下就好了。

原理很简单。而 mMsgRecordPool 之所以设置成了 private 访问权限，是因为，不希望被外部访问到。对于一个类的设计来讲，MsgRecord 是一个非常合格的类了。

应用到我们的消息策略的代码如下:

protected void RegisterMsg(string msgName, Action<object> onMsgReceived)
{MsgDispatcher.Register(msgName, onMsgReceived);// var msgRecord = MsgRecord.Allocate();msgRecord.Name = msgName;msgRecord.OnMsgReceived = onMsgReceived;mMsgRecorder.Add(msgRecord);
}private void OnDestroy()
{OnBeforeDestroy();foreach (var msgRecord in mMsgRecorder){MsgDispatcher.UnRegister(msgRecord.Name,msgRecord.OnMsgReceived);  //msgRecord.Recycle();}mMsgRecorder.Clear();
}

我们发现，在申请对象部分可以简化成如下:

// var msgRecord = MsgRecord.Allocate();
//            
// msgRecord.Name = msgName;
// msgRecord.OnMsgReceived = onMsgReceived;
//            
// mMsgRecorder.Add(msgRecord);mMsgRecorder.Add(MsgRecord.Allocate(msgName, onMsgReceived));

只需要向 MsgRecord.Allocate 增加参数，代码如下:

public static MsgRecord Allocate(string msgName,Action<object> onMsgReceived)
{MsgRecord retMsgRecord = null;retMsgRecord = mMsgRecordPool.Count > 0 ? mMsgRecordPool.Pop() : new MsgRecord();retMsgRecord.Name = msgName;retMsgRecord.OnMsgReceived = onMsgReceived;return retMsgRecord;
}

代码不难，那么到这里，我们的完整的第十三个示例就写完了。

完整示例代码如下:

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;namespace QFramework
{public abstract partial class MonoBehaviourSimplify{List<MsgRecord> mMsgRecorder = new List<MsgRecord>();private class MsgRecord{private static readonly Stack<MsgRecord> mMsgRecordPool = new Stack<MsgRecord>();public static MsgRecord Allocate(string msgName,Action<object> onMsgReceived){MsgRecord retMsgRecord = null;retMsgRecord = mMsgRecordPool.Count > 0 ? mMsgRecordPool.Pop() : new MsgRecord();retMsgRecord.Name = msgName;retMsgRecord.OnMsgReceived = onMsgReceived;return retMsgRecord;}public void Recycle(){Name = null;OnMsgReceived = null;mMsgRecordPool.Push(this);}public string Name;public Action<object> OnMsgReceived;}protected void RegisterMsg(string msgName, Action<object> onMsgReceived){MsgDispatcher.Register(msgName, onMsgReceived);mMsgRecorder.Add(MsgRecord.Allocate(msgName, onMsgReceived));}private void OnDestroy(){OnBeforeDestroy();foreach (var msgRecord in mMsgRecorder){MsgDispatcher.UnRegister(msgRecord.Name,msgRecord.OnMsgReceived);  msgRecord.Recycle();}mMsgRecorder.Clear();}protected abstract void OnBeforeDestroy();}public class MsgDistapcherInMonoBehaviourSimplify : MonoBehaviourSimplify{
#if UNITY_EDITOR[UnityEditor.MenuItem("QFramework/13.消息机制集成到 MonoBehaviourSimplify", false, 14)]private static void MenuClicked(){UnityEditor.EditorApplication.isPlaying = true;new GameObject("MsgReceiverObj").AddComponent<MsgDistapcherInMonoBehaviourSimplify>();}
#endifprivate void Awake(){RegisterMsg("Do", DoSomething);RegisterMsg("Do", DoSomething);RegisterMsg("DO1", _ => { });RegisterMsg("DO2", _ => { });RegisterMsg("DO3", _ => { });}private IEnumerator Start(){MsgDispatcher.Send("Do","hello");yield return new WaitForSeconds(1.0f);MsgDispatcher.Send("Do","hello1");}void DoSomething(object data){// do somethingDebug.LogFormat("Received Do msg:{0}",data);}protected override void OnBeforeDestroy(){}}
}

运行结果如下图: