Unity-自定义事件派发器的两次尝试

一、前言：

在游戏开发的很多时候，需要引用其他类的方法，但是一旦类多起来了，相互引用会导致引用关系混乱，极其难以阅读。

以前初次做抖音小游戏时，和一位经验老道的cocos程序员合作，看到我写的代码他不禁皱起眉头，说我的引用关系太乱了，看不懂，但是他又不知道unity的事件派发器怎么写，就去网上找了一个。简直惊艳到我了。后来在现在公司做，又见到了一种事件派发器，于是心生感慨，模仿写了一个，并写博客记录一下。

二、现在做的事件派发器

1.声明对应的委托，此委托主要为事件用的。委托的所有返回类型都为Void，简化派发器的复杂程度；明确委托的方法参数类型，有几种类型就定义几种委托。

public delegate void VoidDelegate();
public delegate void BoolDelegate(params bool[] parameters);
public delegate void NumberDelegate(params float[] parameters);
public delegate void GameObjectDelegate(params GameObject[] parameters);

2.存储容器，用于存储事件

private static List<VoidDelegate> GameStart_List;

3.监听者，暴露给外部调用者的接口，对监听者的+=或-=对应容器里的Add和Remove

public static event VoidDelegate GameStart_Listener
    {
        add
        {
            if(value != null)
            {
                if(GameStart_List == null)
                {
                    GameStart_List = new List<VoidDelegate>(1);
                }
                GameStart_List.Add(value);
            }
        }
        remove
        {
            if(value != null)
            {
                for(int i = 0;i<GameStart_List.Count;i++)
                {
                    if(GameStart_List[i] != null && GameStart_List[i].Equals(value))
                    {
                        GameStart_List.RemoveAt(i);
                        break;
                    }
                }
            }
        }
    }

4.派发者，因为event只能在声明类内部Invoke，所以需要暴露给外部调用者接口

public static void GameStart_Dispatch()
    {
        if(GameStart_List == null || GameStart_List.Count <= 0)
        {
            return;
        }
        for(int i = 0;i < GameStart_List.Count;i++)
        {
            GameStart_List[i]?.Invoke();
        }
    }

5.上文可看见我的事件叫GameStart,那么我想新增一个GameEnd的事件，岂不是又要写一遍？而且假如我的方法参数是float呢？是bool呢？是GameObject呢？岂不是改动很大？所以我在Unity做了一个自动生成事件的工具

5.1 定义ScriptObject作为配置文件，可随时修改以添加或者删除事件

[CreateAssetMenu]
public class EventHandlerSetting:ScriptableObject
{
    public List<EventType> types;
    public List<EventItem> items;
}

[System.Serializable]
public class EventItem
{
    public string eventName;
    public string typeName;
}

[System.Serializable]
public class EventType
{
    public string typeName;
    public string typeDelegate;
}

5.2 自动生成脚本工具

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

public class CodeGen
{
    private static string SettingPath = @"EventHandleSetting";
    private static EventHandlerSetting SettingObj;
    private static string CodePath = @"Assets\EventHandler\";
    private static string CodeName = "EventHandler.cs";
    private static string LineFeed = "\r\n";
    private static string LineTable = "\t";

    [MenuItem("Tools/EventCodeGen")]
    public static void CreateEventCode()
    {
        if (File.Exists(CodePath+CodeName))
        {
            File.Delete(CodePath + CodeName);
        }
        File.Create(CodePath + CodeName).Dispose();
        LoadSetting();

        File.AppendAllText(CodePath + CodeName, CreateNamespace());
        File.AppendAllText(CodePath + CodeName, CreateDelegate());
        File.AppendAllText(CodePath + CodeName, CreateClass());

        AssetDatabase.Refresh();
    }

    /// <summary>
    /// 加载配置文件
    /// </summary>
    static void LoadSetting()
    {
        SettingObj = Resources.Load<EventHandlerSetting>(SettingPath);
    }

    static string CreateNamespace()
    {
        StringBuilder result = new StringBuilder();
        result.Append("using System;" + LineFeed);
        result.Append("using System.Collections;" + LineFeed);
        result.Append("using System.Collections.Generic;" + LineFeed);
        result.Append("using UnityEngine;" + LineFeed+LineFeed);
        return result.ToString();
    }

    /// <summary>
    /// 创建委托类型
    /// </summary>
    /// <returns></returns>
    static string CreateDelegate()
    {
        StringBuilder result = new StringBuilder();
        string commnPrefix = "public delegate void ";
        using (var e = SettingObj.types.GetEnumerator())
        {
            while (e.MoveNext())
            {
                result.Append(commnPrefix + e.Current.typeDelegate + ";" + LineFeed);
            }
        }
        result.Append(LineFeed);
        return result.ToString();
    }

    /// <summary>
    /// 创建EventHandler类
    /// </summary>
    /// <returns></returns>
    static string CreateClass()
    {
        StringBuilder result = new StringBuilder();
        result.Append("public class EventHandler"+LineFeed);
        result.Append("{"+LineFeed);
        List<EventItem> ls = SettingObj.items;
        for (int i = 0; i < ls.Count; i++)
        {
            string eventName = ls[i].eventName;
            string eventType = ls[i].typeName;
            result.Append(CreateEvent(eventName, eventType));
        }
        result.Append("}");
        return result.ToString();
    }

    /// <summary>
    /// 创建事件派发器
    /// </summary>
    /// <param name="eventName"></param>
    /// <param name="eventType"></param>
    /// <returns></returns>
    static string CreateEvent(string eventName,string eventType)
    {
        StringBuilder result = new StringBuilder();
        result.Append(LineFeed + "#region " + eventName + LineFeed);
        result.Append(MutiLineTable(1) + string.Format("private static List<{0}> {1}_List;", eventType + "Delegate", eventName) + LineFeed);//创建List
        result.Append(CreateListener(eventName, eventType));
        result.Append(CreateDispatch(eventName, eventType));
        result.Append("#endregion"+LineFeed);
        return result.ToString();
    }

    /// <summary>
    /// 创建Listener
    /// </summary>
    /// <param name="eventName"></param>
    /// <param name="eventType"></param>
    /// <returns></returns>
    static string CreateListener(string eventName,string eventType)
    {
        StringBuilder result = new StringBuilder();
        result.Append(MutiLineTable(1) + string.Format("public static event {0} {1}_Listener", eventType + "Delegate", eventName) + LineFeed);
        result.Append(MutiLineTable(1) + "{" + LineFeed);
        #region add
        result.Append(MutiLineTable(2) + "add" + LineFeed);
        result.Append(MutiLineTable(2) + "{" + LineFeed);
        result.Append(MutiLineTable(3) + "if(value != null)" + LineFeed);
        result.Append(MutiLineTable(3) + "{" + LineFeed);
        result.Append(MutiLineTable(4) + string.Format("if({0}_List == null)", eventName) + LineFeed);
        result.Append(MutiLineTable(4) + "{" + LineFeed);
        result.Append(MutiLineTable(5) + string.Format("{0}_List = new List<{1}>(1);", eventName, eventType + "Delegate")+LineFeed);
        result.Append(MutiLineTable(4) + "}" + LineFeed);
        result.Append(MutiLineTable(4) + string.Format("{0}_List.Add(value);", eventName) + LineFeed);
        result.Append(MutiLineTable(3) + "}" + LineFeed);
        result.Append(MutiLineTable(2) + "}" + LineFeed);
        #endregion
        #region remove
        result.Append(MutiLineTable(2) + "remove" + LineFeed);
        result.Append(MutiLineTable(2) + "{" + LineFeed);
        result.Append(MutiLineTable(3) + "if(value != null)" + LineFeed);
        result.Append(MutiLineTable(3) + "{" + LineFeed);
        result.Append(MutiLineTable(4) + string.Format("for(int i = 0;i<{0}_List.Count;i++)", eventName) + LineFeed);
        result.Append(MutiLineTable(4) + "{" + LineFeed);
        result.Append(MutiLineTable(5) + string.Format("if({0}_List[i] != null && {1}_List[i].Equals(value))",eventName,eventName) + LineFeed);
        result.Append(MutiLineTable(5) + "{" + LineFeed);
        result.Append(MutiLineTable(6) + string.Format("{0}_List.RemoveAt(i);" ,eventName) + LineFeed);
        result.Append(MutiLineTable(6) + "break;" + LineFeed);
        result.Append(MutiLineTable(5) + "}" + LineFeed);
        result.Append(MutiLineTable(4) + "}" + LineFeed);
        result.Append(MutiLineTable(3) + "}" + LineFeed);
        result.Append(MutiLineTable(2) + "}" + LineFeed);
        #endregion
        result.Append(MutiLineTable(1) + "}" + LineFeed);
        return result.ToString();
    }

    /// <summary>
    /// 创建Dispatch
    /// </summary>
    /// <param name="eventName"></param>
    /// <param name="eventType"></param>
    /// <returns></returns>
    static string CreateDispatch(string eventName,string eventType)
    {
        StringBuilder result = new StringBuilder();
        result.Append(MutiLineTable(1) + string.Format("public static void {0}_Dispatch({1})", eventName, GetTypeParameter(eventType)) + LineFeed);
        result.Append(MutiLineTable(1) + "{" + LineFeed);
        result.Append(MutiLineTable(2) + string.Format("if({0}_List == null || {1}_List.Count <= 0)", eventName, eventName) + LineFeed);
        result.Append(MutiLineTable(2) + "{" + LineFeed);
        result.Append(MutiLineTable(3) + "return;" + LineFeed);
        result.Append(MutiLineTable(2) + "}" + LineFeed);
        result.Append(MutiLineTable(2) + string.Format("for(int i = 0;i < {0}_List.Count;i++)", eventName) + LineFeed);
        result.Append(MutiLineTable(2) + "{" + LineFeed);
        if (!string.IsNullOrEmpty(GetTypeParameter(eventType)))
        {
            result.Append(MutiLineTable(3) + string.Format("{0}_List[i]?.Invoke(parameters[i]);", eventName) + LineFeed);
        }
        else
        {
            result.Append(MutiLineTable(3) + string.Format("{0}_List[i]?.Invoke();", eventName) + LineFeed);
        }
        result.Append(MutiLineTable(2) + "}" + LineFeed);
        result.Append(MutiLineTable(1) + "}" + LineFeed);
        return result.ToString();
    }

    /// <summary>
    /// 获取字符串中括号中的内容
    /// </summary>
    /// <param name="typeName"></param>
    /// <returns></returns>
    static string GetTypeParameter(string typeName)
    {
        if (string.IsNullOrEmpty(typeName))
        {
            return string.Empty;
        }
        using (var e=SettingObj.types.GetEnumerator())
        {
            while (e.MoveNext())
            {
                if (e.Current.typeName==typeName)
                {
                    string @delegate = e.Current.typeDelegate;
                    string result = @delegate.Substring(@delegate.IndexOf("(") + 1, @delegate.IndexOf(")") - (@delegate.IndexOf("(") + 1));
                    Debug.Log(result);
                    return result;
                }
            }
        }
        return string.Empty;
    }

    /// <summary>
    /// 多个table
    /// </summary>
    /// <param name="count"></param>
    /// <returns></returns>
    static string MutiLineTable(int count)
    {
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < count; i++)
        {
            result.Append(LineTable);
        }
        return result.ToString() ;
    }
}

6.总结

当然，我的这一套事件系统肯定还是有问题的。如果方法参数不止一个float呢？第二个参数是bool？组合起来呢？还有一个问题是，配置文件不够人性化，全部都是字符串，假如多大一个空格或者标点就废了。还有一个非常严重的问题，如果生成的脚本，在语法上有错，不能通过编译器，Unity就会报错，再次点击生成就不会生效。我认识的一个主程让我在Unity外部生成，不要依赖Unity，且使用类似Lua、Python这种脚本语言，目前还不会哈哈哈哈。

三、以前做的事件派发器

1.需要一个通用的参数类型，叫EventArgs,基础类型为Systen.Object

public class EventArgs
{
    private List<System.Object> parameters;
    public int Count
    {
        get
        {
            if (parameters!=null)
            {
                return parameters.Count;
            }
            else
            {
                Debug.Log("parameters is not init");
                return 0;
            }
        }
    }
    public EventArgs(params System.Object[] parameters)
    {
        if (this.parameters==null)
        {
            this.parameters = new List<object>();
        }
        for (int i = 0; i < parameters.Length; i++)
        {
            this.parameters.Add(parameters[i]);
        }
    }
    public System.Object this[int index]
    {
        get
        {
            if (index>=0||index<parameters.Count)
            {
                return parameters[index];
            }
            else
            {
                Debug.LogError("index must be in range of parameters");
                return null;
            }
        }
    }
}

2.还是那句老话，事件派发器需要容器、监听、派发三部分。

public class EventDispatcher
{
    public delegate void Listener(EventArgs args);
    private static Dictionary<string, Listener> cacheEvents = new Dictionary<string, Listener>();

    public static void Attach(string tag,Listener listen)
    {
        if (cacheEvents==null)
        {
            cacheEvents = new Dictionary<string, Listener>();
        }
        if (cacheEvents.ContainsKey(tag))
        {
            Debug.LogWarning("this tag already exsit in cache,please check agin,tag name:" + tag);
            return;
        }
        if (listen==null)
        {
            Debug.LogWarning("listen is null,cache failed");
            return;
        }
        cacheEvents.Add(tag, listen);
    }

    public static void Detach(string tag)
    {
        if (!cacheEvents.ContainsKey(tag))
        {
            Debug.LogWarning("tag is not exsit in cache,tag name:"+tag);
            return;
        }
        cacheEvents.Remove(tag);
    }

    public static void Dispatch(string tag,EventArgs args)
    {
        if (!cacheEvents.ContainsKey(tag))
        {
            Debug.LogWarning("this tag does not exsit in cache,please check agin,tag name:" + tag);
            return;
        }
        if (cacheEvents[tag]==null)
        {
            Debug.LogWarning("this listen is null,invoke failed");
            return;
        }
        cacheEvents[tag].Invoke(args);
    }
}

3.总结：

此事件派发器也存在缺陷，任何方法的参数类型都会被转换成System.Object类型，有多余的封装箱操作。且不能重复添加一个方法，至少他的tag不能一样。代码可读性差，报错了都不知道在哪儿。

四、关于事件派发器自己的看法

我相信没有完美的派发器这一说，好的派发器与坏的派发器区别在于，调用是否方便？会不会存在隐藏的危险bug？性能上如何？不同项目有不同的事件派发器，适合自己的才是最好的。如果强行将事件派发器做成那种万金油工具，且不论他是否真的是万金油，代码开发成本之大，耗费时间之长，也不是一般小游戏公司能够耗得起的。上文所述两个派发器，实际上都可以用，而且经历过实战的，并没有什么大问题。