【C#设计模式(14)——责任链模式( Chain-of-responsibility Pattern)】

前言

责任链模式通过将请求和处理者解耦，关联多个处理者形成一个链条，使每个处理者都有机会处理请求，避免了将所有处理逻辑集中在一个对象中的复杂性。

代码

//请求者
public class Requestor
{
    private string content;
    public string Content { get { return content; } }
    public Requestor(string content) 
    {
        this.content = content;
    }
}
//处理者
public abstract class Handler
{
    public abstract void SetNext(Handler handler);
    public abstract void HandleRequest(Requestor requestor);
}
//处理者:接收者A
public class ReceiverA : Handler
{
    private Handler nextHandler;
    public override void SetNext(Handler handler)
    {
        nextHandler = handler;
    }

    public override void HandleRequest(Requestor requestor)
    {
        if (requestor.Content.Equals("A")) 
        {
            Console.WriteLine("receiverA handle the request...");
        }
        else if(nextHandler!=null)
        {
            nextHandler.HandleRequest(requestor);
        }
    }
}
//处理者:接收者B
public class ReceiverB : Handler
{
    private Handler nextHandler;
    public override void HandleRequest(Requestor requestor)
    {
        if (requestor.Content.Equals("B"))
        {
            Console.WriteLine("receiverB hanlde the request...");
        }else if (nextHandler != null)
        {
            nextHandler.HandleRequest(requestor);
        }
    }
    public override void SetNext(Handler handler)
    {
        this.nextHandler = handler;
    }
}


/*
 * 行为型模式：Behavioral Pattern
 * 责任链模式： Chain-of-responsibility Pattern
 */
internal class Program
{
    static void Main(string[] args)
    {
        //创建接收请求
        Handler handlerA = new ReceiverA();
        Handler handlerB = new ReceiverB();

        //设置下一个请求处理者
        handlerA.SetNext(handlerB);

        //创建请求者A，并处理请求
        Requestor receiverA = new Requestor("A");
        handlerA.HandleRequest(receiverA);

        Requestor receiverB = new Requestor("B");
        handlerA.HandleRequest(receiverB);

        Requestor requestorC = new Requestor("C");
        handlerA.HandleRequest(requestorC);

        Requestor receiverA2 = new Requestor("A");
        handlerA.HandleRequest(receiverA2);

        Console.ReadLine();
    }
}

运行结果