C#中关于委托练习的一个例子

委托的本质就是一个类，任何可以声明类的地方都可以声明委托。

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace @delegate

{

delegate void EatDelegate(string food);

class program //定义一个类

{

static void zsEat(string food) //定义静态的方法

{

Console.WriteLine("张三" + food);

}

static void lsEat(string food)

{

Console.WriteLine("李四" + food);

}

static void wwEat(string food)

{

Console.WriteLine("王五" + food);

}

static void Main(string[] args)

{

EatDelegate zs = new EatDelegate(zsEat);

EatDelegate ls = new EatDelegate(lsEat);

EatDelegate ww = new EatDelegate(wwEat);

EatDelegate eatChain;

Console.WriteLine("张三、李四、王五开座谈会");

eatChain = zs + ls + ww;

eatChain("西瓜");

Console.WriteLine("李四出去接电话");

eatChain -= ls;

eatChain("香蕉");

Console.WriteLine("李四回来了");

eatChain += ls;

eatChain("桔子");

}

}

}

//上面的例子是委托对静态方法的代理，下面改为对动态方法的代理，代码如下：

namespace @delegate

{

delegate void EatDelegate(string food);

class Man //定义一个类Man

{

private string name; //定义一个字段name

public Man(string name) //构造Man函数，为了给字段name赋值

{

this.name = name;

}

public void eat(string food) //定义吃东西的方法

{

Console.WriteLine(name + "吃" + food);

}

}

class Party

{

static void eatToghter(string food, params EatDelegate[] value)

{

if (value == null)

{

Console.WriteLine("座谈会结束");

}

else

{

EatDelegate eatChain = null;

foreach (EatDelegate ed in value)

eatChain += ed;

eatChain(food);

Console.WriteLine();

}

}

static void Main(string[] args)

{

Man ZS = new Man("张三"); //实例化一个张三

Man LS = new Man("李四"); //实例化一个李四

Man WW = new Man("王五"); //实例化一个王五

EatDelegate zs = new EatDelegate(ZS.eat); //使用代理

EatDelegate ls = new EatDelegate(LS.eat);

EatDelegate ww = new EatDelegate(WW.eat);

EatDelegate eatChain = null;

Console.WriteLine("张三、李四、王五开座谈会");

eatToghter("西瓜", zs, ls, ww);

Console.WriteLine("李四出去接电话");

eatToghter("香蕉", zs, ww);

Console.WriteLine("李四回来了");

eatToghter("桔子", zs, ls, ww);

eatToghter(null, null);

}

}

}