责任链模式(Chain of Responsibility Pattern)

using System;

class ChainofResponsibilityPattern {

// Chain of responsibility pattern       Judith Bishop June 2007

class Handler {
Handler next;
int id;
public int Limit {get; set;}

public Handler (int id, Handler handler) {
this.id = id;
Limit = id*1000;
next = handler;
}

public string HandleRequest(int data) {
if (data < Limit)
return "Request for " +data+" handled at level "+id;
else if (next!=null)
return next.HandleRequest(data);
else return ("Request for " +data+" handled BY DEFAULT at level "+id);
}
}

static void Main () {

Handler start = null;
for (int i=5; i>0; i--) {
Console.WriteLine("Handler "+i+" deals up to a limit of "+i*1000);
start = new Handler(i,  start);
}

int [] a = {50,2000,1500,10000,175,4500};
foreach (int i in a)
Console.WriteLine(start.HandleRequest(i));
Console.ReadKey();
}
}
/*
Handler 5 deals up to a limit of 5000
Handler 4 deals up to a limit of 4000
Handler 3 deals up to a limit of 3000
Handler 2 deals up to a limit of 2000
Handler 1 deals up to a limit of 1000
Request for 50 handled at level 1
Request for 2000 handled at level 3
Request for 1500 handled at level 2
Request for 10000 handled BY DEFAULT at level 5
Request for 175 handled at level 1
Request for 4500 handled at level 5
*/