二十六.职责链模式

职责连模式：

       ChainOfResponsibility:使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

优点：

       请求是沿链传递至有一个ConcreteHandler对象处理它

       但要注意链尾是否能处理所有请求

Demo1：

       //处理请求的接口

   abstract class Handler

    {

       protected Handler successor;

       public void SetSuccessor(Handler successor)//设置继任者

       {

           this.successor = successor;

       }

       //处理请求的抽象方法

       public abstract void HandlerRequest(int request);

    }

       // 有权处理0-10之间

   class ConcreteHandler1:Handler

    {

       public override voidHandlerRequest(int request)

       {

           if (request >= 0 && request < 10)

           {

                Console.WriteLine("{0}处理请求{1}",

                    this.GetType().Name,request);

           }

           else if (successor != null)

           {

               successor.HandlerRequest(request);//转移到下一位

           }

       }

    }

   // 有权处理10-20之间

   class ConcreteHandler2 : Handler

    {

       public override void HandlerRequest(int request)

       {

           if (request >= 10&& request < 20)

           {

                Console.WriteLine("{0}处理请求{1}",

                    this.GetType().Name,request);

           }

           else if (successor != null)

           {

                successor.HandlerRequest(request);//转移到下一位

           }

       }

}

。。。。。。

static void Main(string[]args)

       {

           Handler h1 = new ConcreteHandler1();

           Handler h2 = new ConcreteHandler2();

           Handler h3 = new ConcreteHandler3();

           h1.SetSuccessor(h2);

           h2.SetSuccessor(h3);

           int[] request = { 2,3,12,14,3,28};

           foreach (int i in request)

           {

                h1.HandlerRequest(i);

           }

           Console.ReadKey();

       }