职责链模式实例（C#）

下面是使用指责链模式的一个具体的实例，可以方便的理解指责链模式。

其实指责链简单的来说，就是把一个指责的流程定义出来，像一条链路一样，每一个结点有自己的处理范围，若不能处理，则传到自己的引用的下一个结点。

下面的实例也是这样的一个简单的流程。每一笔预算需要不同的人审核，不同的人有不同的审核范围，若款项在自己的处理范围之内，就可以直接处理掉，若不在自己的范围内，就传入到自己的上级进行处理。在写实例的时候，就需要用户把处理的过程给定义出来。既是把那条处理的链路定义出来。

下面是示例的源代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Chain_of_Responsibility_Use
{
    class PurchaseReuest
    {
        private int number;
        private double amount;
        private string purpose;

        public PurchaseReuest(int number, double amount, string purpose)
        {
            this.amount = amount;
            this.number = number;
            this.purpose = purpose;
        }
        public int Number
        {
            get { return number; }
            set { number = value; }
        }
        public double Amount
        {
            get { return amount; }
            set { amount = value; }
        }
        public string Purpose
        {
            get { return purpose; }
            set { purpose = value; }
        }
    }
    abstract class Approver
    {
        protected string name;
        protected Approver successor;

        public Approver(string name)
        {
            this.name = name;
        }
        public void setSuccessor(Approver successor)
        {
            this.successor = successor;
        }
        abstract public void ProcessRequest(PurchaseReuest request);
    }
    //ConcreteHandler
    class Director : Approver
    {
        public Director(string name)
            : base(name) { }
        public override void ProcessRequest(PurchaseReuest request)
        {
            //throw new NotImplementedException();
            if (request.Amount < 10000.0)
                Console.WriteLine("{0} {1} approved request# {2} ", this, name, request.Number);
            else
                if (successor != null)
                    successor.ProcessRequest(request);
        }
    }
    //ConcreteHandler
    class VicePresident : Approver
    {
        public VicePresident(string name) : base(name) { }
        public override void ProcessRequest(PurchaseReuest request)
        {
            //throw new NotImplementedException();
            if (request.Amount < 25000.0)
                Console.WriteLine("{0} {1} approved request# {2} ", this, name, request.Number);
            else
                if (successor != null)
                    successor.ProcessRequest(request);
        }
    }
    //ConcreteHandler
    class President : Approver
    {
        public President(string name) : base(name) { }
        public override void ProcessRequest(PurchaseReuest request)
        {
            //throw new NotImplementedException();
            if (request.Amount < 100000.0)
                Console.WriteLine("{0} {1} approved request# {2} ", this, name, request.Number);
            else
                Console.WriteLine("Request# {0} request " + "an executie meeting ! ", request.Number);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Director Larry = new Director("Larry");
            VicePresident Sam = new VicePresident("Sam");
            President Tammy = new President("Tammy");
            Larry.setSuccessor(Sam);
            Sam.setSuccessor(Tammy);

            PurchaseReuest rs = new PurchaseReuest(2034, 350.00, "Supplies");
            Larry.ProcessRequest(rs);

            PurchaseReuest rx = new PurchaseReuest(2035, 12590.10, "Project X");
            Larry.ProcessRequest(rx);

            PurchaseReuest ry = new PurchaseReuest(2036, 122100.00, "Project Y");
            Larry.ProcessRequest(ry);

            Console.ReadKey();
        }
    }
}

下面是示例的类图：

下面是示例的关系图：

示例的运行截图如下：