责任链模式(Chain of Responsibility Pattern)
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。
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