C#行为模式列子

惜

一 、  责任链模式的实际应用案例

下面的责任链模式代码演示了不同职务的人根据所设定的权限对一个购买请求作出决策或将其交给更高的决策者。

[C#] 纯文本查看 复制代码

using System;
// "Handler"
abstract class Approver
{
    // Fields
    protected string name;
    protected Approver successor;
    // Constructors
    protected Approver(string name)
    {
        this.name = name;
    }
    // Methods
    public void SetSuccessor(Approver successor)
    {
        this.successor = successor;
    }
    public abstract void ProcessRequest(PurchaseRequest request);
}
// "ConcreteHandler"
class Director : Approver
{
    // Constructors
    public Director(string name) : base(name) { }
    // Methods
    public override void ProcessRequest(PurchaseRequest request)
    {
        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
{
    // Constructors
    public VicePresident(string name) : base(name) { }
    // Methods
    public override void ProcessRequest(PurchaseRequest request)
    {
        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
{
    // Constructors
    public President(string name) : base(name) { }
    // Methods
    public override void ProcessRequest(PurchaseRequest request)
    {
        if (request.Amount < 100000.0)
            Console.WriteLine("{0} {1} approved request# {2}",
            this, name, request.Number);
        else
            Console.WriteLine("Request# {0} requires " +
            "an executive meeting!", request.Number);
    }
}
// Request details
class PurchaseRequest
{
    // Member Fields
    // Constructors
    public PurchaseRequest(int number,
    double amount, string purpose)
    {
        Number = number;
        Amount = amount;
        Purpose = purpose;
    }
    // Properties
    public double Amount { get; set; }

    public string Purpose { get; set; }

    public int Number { get; set; }
}
/// <summary>
/// ChainApp Application
/// </summary>
public class ChainApp
{
    public static void Main(string[] args)
    {
        // Setup Chain of Responsibility
        Director Larry = new Director("Larry");
        VicePresident Sam = new VicePresident("Sam");
        President Tammy = new President("Tammy");
        Larry.SetSuccessor(Sam);
        Sam.SetSuccessor(Tammy);
        // Generate and process different requests
        PurchaseRequest rs = new PurchaseRequest(2034, 350.00, "Supplies");
        Larry.ProcessRequest(rs);
        PurchaseRequest rx = new PurchaseRequest(2035, 32590.10, "Project X");
        Larry.ProcessRequest(rx);
        PurchaseRequest ry = new PurchaseRequest(2036, 122100.00, "Project Y");
        Larry.ProcessRequest(ry);
    }
}

二 、  责任链模式的实现

    责任链模式并不创建责任链。责任链的创建必须由系统的其它部分创建出来。

    责任链模式降低了请求的发送端和接收端之间的耦合，使多个对象都有机会处理这个请求。一个链可以是一条线，
一个树，也可以是一个环。如下图所示，责任链是一个树结构的一部分。

Amy

强烈支持楼主ing……

范范

我只是路过打酱油的。

liu

强烈支持楼主ing……

站长苏飞

我只是路过打酱油的。

竹林风

我只是路过打酱油的。