设计模式 - Chain of Responsibility Pattern(责任链模式)

介绍
为解除请求的发送者和接收者之间耦合，而使多个对象都有机会处理这个请求。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它。

示例
有一个Message实体类，某个类对它的操作有Insert()方法。现在要求根据插入信息的字符长度，让不同的对象去处理，这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它。

(图示 见附件)

MessageModel

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

namespace Pattern.ChainOfResponsibility
{ 
    /**//// <summary> 


    /// Message实体类
    /// </summary>
    public class MessageModel
    { 

        /**//// <summary> 
        /// 构造函数
     /// </summary>
        /// <param name="msg">Message内容</param> 
        /// <param name="pt">Message发布时间</param>
        public MessageModel(string msg, DateTime pt)
        { 
            this._message = msg;
            this._publishTime = pt;
        }

        private string _message; 
        /**//// <summary> 
        /// Message内容
        /// </summary>
        public string Message
        { 
            get { return _message; } 
            set { _message = value; } 

        }

        private DateTime _publishTime;
        /**//// <summary> 
        /// Message发布时间
        /// </summary>
        public DateTime PublishTime
        { 

            get { return _publishTime; } 

            set { _publishTime = value; } 
        }
    }
}

 

 

SqlMessage

 

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

namespace Pattern.ChainOfResponsibility
{ 
    /**//// <summary> 

    /// Sql方式操作Message
    /// </summary>
    public class SqlMessage
    { 
        /**//// <summary> 
        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param> 
        /// <returns></returns>
        public bool Insert(MessageModel mm)
        { 
            // 代码略
            return true;
        }
    }
} 

 

 

 

AbstractExecutor

 

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

namespace Pattern.ChainOfResponsibility 

{
    /**//// <summary> 
    /// 抽象处理者(Handler)角色
    /// </summary>
    public abstract class AbstractExecutor
    { 

        /**//// <summary>  
        /// 抽象处理者(Handler)角色
        /// </summary>
        protected AbstractExecutor _executor;

        /**//// <summary> 
        /// 设置责任链的上一级对象
        /// </summary>
        /// <param name="executor"></param>
        public void SetSuccessor(AbstractExecutor executor) 


        {
            this._executor = executor; 

        }

        /**//// <summary> 

        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param> 
        /// <returns>执行者；内容；时间</returns>
        public abstract string Insert(MessageModel mm);
    } 
}

 

 

 

Employee

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

namespace Pattern.ChainOfResponsibility 
{
    /**//// <summary> 
    /// 具体处理者(ConcreteHandler)角色
    /// </summary>
    public class Employee : AbstractExecutor
    { 
        /**//// <summary> 

        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param> 
        /// <returns>执行者；内容；时间</returns>
        public override string Insert(MessageModel mm)
        { 
            string rtn = "";

            // 插入的信息字符数小于5
            if (mm.Message.Length < 5) 
            { 

                SqlMessage m = new SqlMessage();

                if (m.Insert(mm))
                { 
                    rtn = "执行者：雇员" + " 内容：" + mm.Message + " 时间：" + mm.PublishTime.ToString(); 

                }
            }
            // 否则让上级去执行
            else if (base._executor != null) 

            { 

                rtn = _executor.Insert(mm);
            }

            return rtn;
        }
    } 
}

 

 

Leader

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

namespace Pattern.ChainOfResponsibility 

{
    /**//// <summary> 
    /// 抽象处理者(Handler)角色
    /// </summary>
    public class Leader : AbstractExecutor
    { 
        /**//// <summary> 
        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param> 
        /// <returns>执行者；内容；时间</returns>
        public override string Insert(MessageModel mm)
        { 
            string rtn = "";

            // 插入的信息字符数小于10
            if (mm.Message.Length < 10) 
            { 
                SqlMessage m = new SqlMessage();

                if (m.Insert(mm))
                { 
                    rtn = "执行者：主管" + " 内容：" + mm.Message + " 时间：" + mm.PublishTime.ToString(); 
                }
            }
            // 否则让上级去执行
            else if (base._executor != null) 
            { 
                rtn = _executor.Insert(mm);
            }

            return rtn;
        }
    } 

}

 

 

Manager

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

namespace Pattern.ChainOfResponsibility 

{
    /**//// <summary> 
    /// 抽象处理者(Handler)角色
    /// </summary>
    public class Manager : AbstractExecutor
    { 


        /**//// <summary> 

        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param> 


        /// <returns>执行者；内容；时间</returns>
        public override string Insert(MessageModel mm)
        { 
            string rtn = "";

            // 插入的信息字符数小于15
            if (mm.Message.Length < 15) 
            { 

                SqlMessage m = new SqlMessage();

                if (m.Insert(mm))
                { 
                    rtn = "执行者：经理" + " 内容：" + mm.Message + " 时间：" + mm.PublishTime.ToString(); 

                }
            }
            else
            { 

                rtn = "你所插入的Message不符合要求";
            }

            return rtn;
        } 


    }
}

 

 

client

using System;
using System.Data;
using System.Configuration; 


using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts; 


using System.Web.UI.HtmlControls;

using Pattern.ChainOfResponsibility;

public partial class ChainOfResponsibility : System.Web.UI.Page
{ 
    protected void Page_Load(object sender, EventArgs e)
    { 

        AbstractExecutor employee = new Employee();
        AbstractExecutor leader = new Leader();
        AbstractExecutor manager = new Manager(); 
        employee.SetSuccessor(leader);
        leader.SetSuccessor(manager);

        Response.Write(employee.Insert(new MessageModel("abcd", DateTime.Now)));
        Response.Write("<br />"); 

        Response.Write(employee.Insert(new MessageModel("abcdefgh", DateTime.Now)));
        Response.Write("<br />");
        Response.Write(employee.Insert(new MessageModel("abcdefghigkl", DateTime.Now))); 

        Response.Write("<br />");
        Response.Write(employee.Insert(new MessageModel("abcdefghigklmnop", DateTime.Now)));
    }
} 

 

 

运行结果
执行者：雇员 内容：abcd 时间：2007-4-22 20:04:41
执行者：主管 内容：abcdefgh 时间：2007-4-22 20:04:41
执行者：经理 内容：abcdefghigkl 时间：2007-4-22 20:04:41
你所插入的Message不符合要求