1、在Unity中点击Button显示文本的方法
①在Button上挂载脚本
代码语言：c#复制using UnityEngine;
using UnityEngine.UI;
public class BtnClick:MonoBehaviour
{
public Text text;
private void Awake()
{
GetComponent<Button>().onClick.AddListener(()=>
{
text.text = "这是一条文本";
});
}
}在Button组件上挂载脚本，拖动文本到Button组件脚本上。
这种方式的耦合性太强，一旦文本丢失或者未将文本拖如到Button的脚本上的话，就会导致程序无法执行。
②通过单例模式，在文本组件上挂载脚本
text上挂载的脚本
代码语言：c#复制using UnityEngine;
using UnityEngine.UI;
public class ShowText : MonoBehaviour
{
public static ShowText Instance;
private void Awake()
{
Instance = this;
}
public void Show(string str)
{
GetComponent<Text>().text = str;
}
}
Button组件上挂载的脚本
代码语言：c#复制using UnityEngine;
using UnityEngine.UI;
public class BtnClick:MonoBehaviour
{
private void Awake()
{
GetComponent<Button>().onClick.AddListener(()=>
{
ShowText.Instance.Show("这是一条文本");
});
}
}单例模式存在的问题：当text上的单例模式没被赋值时，按钮上的脚本依然有问题，耦合性依然比较强。
③采用事件监听解耦合
text上挂载的脚本
代码语言：c#复制using UnityEngine;
using UnityEngine.UI;
public class ShowText : MonoBehaviour
{
private void Awake()//添加监听
{
gameObject.SetActive(false);
EventCenter.AddListener<string>(EventType.ShowText,Show);//委托，<>中变量类型与Show函数中的参数有关
}
private void OnDestroy()//消除监听
{
EventCenter.RemoveListener<string>(EventType.ShowText,Show);
}
public void Show(string str)
{
gameObject.SetActive(true);
GetComponent<Text>().text = str;
}
}
Button组件上挂载的脚本
代码语言：c#复制using UnityEngine;
using UnityEngine.UI;
public class BtnClick:MonoBehaviour
{
private void Awake()
{
GetComponent<Button>().onClick.AddListener(()=>
{
EventCenter.Broadcast(EventType.ShowText,"这是一条文本");
});
}
}Button组件发布一个广播，谁监听到就处理，没有监听的也不会报错，只是不会执行相应程序，耦合性小了很多。
其中EventCenter类如下：
代码语言：c#复制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>();
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()));
}
}
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}，要移除的委托类型为{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));
}
}
private static void OnListenerRemoved(EventType eventType)
{
if (m_EventTable[eventType] == null)
{
m_EventTable.Remove(eventType);
}
}
//no parameters
public static void AddListener(EventType eventType, CallBack callBack)
{
OnListenerAdding(eventType, callBack);
m_EventTable[eventType] = (CallBack)m_EventTable[eventType] callBack;
}
//Single parameters
public static void AddListener<T>(EventType eventType, CallBack<T> callBack)
{
OnListenerAdding(eventType, callBack);
m_EventTable[eventType] = (CallBack<T>)m_EventTable[eventType] callBack;
}
//two parameters
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 parameters
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 parameters
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 parameters
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;
}
//no parameters
public static void RemoveListener(EventType eventType, CallBack callBack)
{
OnListenerRemoving(eventType, callBack);
m_EventTable[eventType] = (CallBack)m_EventTable[eventType] - callBack;
OnListenerRemoved(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;
OnListenerRemoved(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;
OnListenerRemoved(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;
OnListenerRemoved(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;
OnListenerRemoved(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;
OnListenerRemoved(eventType);
}
//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));
}
}
}
}
EventType类中处理了不同事件类型的监听
EventType为事件的枚举，可以自定义添加监听的事件：
代码语言：c#复制public enum EventType
{
ShowText,
}
CallBack为定义委托的类
代码语言：c#复制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);就以上内容看，事件的监听是处理解耦的好的方法。
关于事件监听的弊端：添加监听的时候的参数类型的顺序必须是和函数的参数的顺序是一致的，当参数较多的时候，比较容易出错
