GoF——职责链模式

职责链模式（chain of Responsibility）：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。

结构图：

using System;
using System.Collections.Generic;
using System.Text;

namespace 职责链模式
{
class Program
{
static void Main(string[] args)
{
Handler h1 = new ConcreteHandler1();
Handler h2 = new ConcreteHandler2();
Handler h3 = new ConcreteHandler3();
h1.SetSuccessor(h2);
h2.SetSuccessor(h3);

int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 };

foreach (int request in requests)
{
h1.HandleRequest(request);
}

Console.Read();

}
}

abstract class Handler
{
protected Handler successor;

public void SetSuccessor(Handler successor)
{
this.successor = successor;
}

public abstract void HandleRequest(int request);
}

class ConcreteHandler1 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 0 && request < 10)
{
Console.WriteLine("{0}  处理请求  {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}

class ConcreteHandler2 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 10 && request < 20)
{
Console.WriteLine("{0}  处理请求  {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}

class ConcreteHandler3 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 20 && request < 30)
{
Console.WriteLine("{0}  处理请求  {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}

}

View Code

2016-04-08