C#之—委托

（1）定义委托：（百度百科样例，只有写了才有收获）

namespace Entrust
{
    public delegate void GreetingDelegate(string name); //定义委托
    class Class1
    {
        public void EnglishGreeting(string name)
        {
            Console.WriteLine("Good Morning." + name);
        }

        public void ChineseGreeting(string name)
        {
            Console.WriteLine("早上好." +name);
        }

        public void GreetPeople(string name, GreetingDelegate MakeGreeting)
        {
            MakeGreeting(name);
        }
    }
}

测试类：

namespace Entrust
{
    class TestMain
    {
        static void Main(string[] args)
        {
            Class1 c = new Class1();

            //c.GreetPeople("San Zhang",c.EnglishGreeting);
            //c.GreetPeople("张三", c.ChineseGreeting);

            //Console.WriteLine("委托变量！");
            //GreetingDelegate delegate1 = c.EnglishGreeting;
            //GreetingDelegate delegate2 = c.ChineseGreeting;
            //c.GreetPeople("张三", delegate2);
            //c.GreetPeople("San Zhang", delegate1);

            //Console.WriteLine("多个方法绑定同一个委托！");
            //GreetingDelegate delegate1;
            //delegate1 = c.EnglishGreeting;
            //delegate1 += c.ChineseGreeting;
            //c.GreetPeople("李四",delegate1);

            //Console.WriteLine("直接调用委托！");
            //GreetingDelegate delegate1;
            //delegate1 = c.EnglishGreeting;
            //delegate1 += c.ChineseGreeting;
            //delegate1("小张");

            //GreetingDelegate delegate1 = new GreetingDelegate(c.EnglishGreeting);
            //delegate1 += c.ChineseGreeting;
            //delegate1("小李");

            GreetingDelegate delegate1 = c.EnglishGreeting;
            delegate1 += c.ChineseGreeting; //绑定委托
            delegate1 -= c.EnglishGreeting; //解除委托
            delegate1("小张");
        }
    }
}

（2）定义委托事件（封装属性和方法）

namespace Entrust
{
    public delegate void GreetingDelegate1(string name);

    class GreetingManage
    {
        public event GreetingDelegate1 MakeGreet;//这里声明一个事件

        public GreetingDelegate1 delegate1;
        public void GreetPeople(string name)
        {
            //if (delegate1 != null)
            //    delegate1(name);
            MakeGreet(name);
        }
    }
}

执行的方法类

namespace Entrust
{
    class GreetingLanguage
    {
        public void EnglishGreeting(string name)
        {
            Console.WriteLine("Morning, " + name);
        }

        public void ChineseGreeting(string name) 
        {
            Console.WriteLine("早上好, " + name);
        }
    }
}

测试类：

namespace Entrust
{
    class TestMain
    {
        static void Main(string[] args)
        {
            GreetingLanguage gl = new GreetingLanguage();
            GreetingManage gm = new GreetingManage();
            //gm.delegate1 = gl.EnglishGreeting;
            gm.MakeGreet += gl.ChineseGreeting;
            gm.GreetPeople("小张");
            Console.ReadKey();
        }
    }
}

（3）委托弥补观察者模式的不足（若观察者不存在）详见（设计模式之—观察者模式）
通知者接口类（Subject）

namespace Observer_Pattern.CLASS
{
    interface Subject
    {
        void Notify(); //通知
        string SubjectState
        {
            get;
            set;
        }
    }
}

秘书类（secreter）实现通知者接口

namespace Observer_Pattern.CLASS
{
    public delegate void EventHandler(); //声明一个委托
    class Secretary:Subject
    {
        public event EventHandler Update; //声明一事件Update，类型为委托EventHandler
        private string action;

        /// <summary>
        /// 通知
        /// </summary>
        public void Notify() 
        {
            Update();
        }

        public string SubjectState
        {
            get { return action; }
            set { action = value; }
        }
    }
}

 炒股工作者（stockWorker）

namespace Observer_Pattern.CLASS
{
    class StockObserver
    {
        private string name;
        private Subject sub;
        public StockObserver(string name, Subject sub)
        {
            this.name = name;
            this.sub = sub;
        }
        public void StockUpdate()
        {
            Console.WriteLine("{0} ，{1} 关闭股票软件，继续工作！",sub.SubjectState,name);
        }
    }
}

看NBA工作者（NBAWorker）

namespace Observer_Pattern.CLASS
{
    class NBAObserver
    {
        private string name;
        private Subject sub;
        public NBAObserver(string name, Subject sub)
        {
            this.name = name;
            this.sub = sub;
        }

        public void NBAUpdate()
        {
            Console.WriteLine("{0} ，{1} 关闭NBA视频，继续工作！",sub.SubjectState,name);
        }
    }
}

测试类（TestMain）

namespace ObserverPattern_Entrust_
{
    class TestMain
    {
        static void Main(string[] args)
        {
            Secretary mishu = new Secretary();
            StockObserver worker1 = new StockObserver("小张", mishu);
            NBAObserver worker2 = new NBAObserver("小李", mishu);

            mishu.Update += worker1.StockUpdate; //绑定委托
            mishu.Update += worker2.NBAUpdate; //绑定委托

            mishu.SubjectState = "老板回来了";
            mishu.Notify(); //调用委托

            Console.ReadLine();
        }
    }
}

测试结果：