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设计模式 - Template Method Pattern(模板
方法模式)
作者：
webabcd
介绍
定义
一个操作中的算法的骨架，而将一些步骤延迟到子类中。Template Method使得子类可以不改变
一个算法的结构即可重定义该算法的某些特定步骤。
示例
有
一个Message
实体类，对它的操作有Get()
方法，每次Get()之前要使用ValidateUser()
方法来检查当前
用户是否有权限，
获取数据可能在
sqlServer
数据库中或Xml
文件里。（这里先检查
用户的权限，再
获取数据就是算法的骨架，
获取数据延迟到子类中实现）
MessageModel
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.TemplateMethod
{
/**//// <summary>
/// Message实体类
/// </summary>
public class MessageModel
{
/**//// <summary>
/// 构造函数
/// </summary>
/// <p@R_502_6460@m name="msg">Message内容</p@R_502_6460@m>
/// <p@R_502_6460@m name="pt">Message发布时间</p@R_502_6460@m>
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
{
@H_56_502@
get
{ return _publishTime; }
set
{ _publishTime = value; }
}
}
}
AbstractMessageTemplate
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.TemplateMethod
{
/**//// <summary>
/// 模板方法抽象类
/// </summary>
public abstract class AbstractMessageTemplate
{
/**//// <summary>
/// UserId
/// </summary>
protected string _userId;
/**//// <summary>
/// 构造函数
/// </summary>
/// <p@R_502_6460@m name="userId">UserId</p@R_502_6460@m>
public AbstractMessageTemplate(string userId)
{
this._userId = userId;
}
/**//// <summary>
/// 验证用户是否合法
/// </summary>
/// <returns></returns>
public virtual bool ValidateUser()
{
if (this._userId == "admin")
{
return true;
}
else
{
return false;
}
}
/**//// <summary>
/// 获取MessageModel列表
/// </summary>
/// <returns></returns>
public abstract List<MessageModel> Get();
/**//// <summary>
/// 模板方法：先验证用户是否合法，再获取MessageModel列表
/// </summary>
/// <returns></returns>
public List<MessageModel> TemplateMethodGet()
{
if (ValidateUser())
{
return Get();
}
else
{
List<MessageModel> l = new List<MessageModel>();
l.Add(new MessageModel("无权获取", DateTime.Now));
return l;
}
}
}
}
sqlMessage
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.TemplateMethod
{
/**//// <summary>
/// sql方式操作Message
/// </summary>
public class sqlMessage : AbstractMessageTemplate
{
/**//// <summary>
/// 构造函数
/// </summary>
/// <p@R_502_6460@m name="userId">UserId</p@R_502_6460@m>
public sqlMessage(string userId)
: base(userId)
{
}
/**//// <summary>
/// 获取Message
/// </summary>
/// <returns></returns>
public override List<MessageModel> Get()
{
List<MessageModel> l = new List<MessageModel>();
l.Add(new MessageModel("sql方式获取Message", DateTime.Now));
return l;
}
}
}
XmlMessage
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.TemplateMethod
{
/**//// <summary>
/// Xml方式操作Message
/// </summary>
public class XmlMessage : AbstractMessageTemplate
{
/**//// <summary>
/// 构造函数
/// </summary>
/// <p@R_502_6460@m name="userId">UserId</p@R_502_6460@m>
public XmlMessage(string userId)
: base(userId)
{
}
/**//// <summary>
/// 获取Message
/// </summary>
/// <returns></returns>
public override List<MessageModel> Get()
{
List<MessageModel> l = new List<MessageModel>();
l.Add(new MessageModel("XML方式获取Message", DateTime.Now));
return l;
}
}
}
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.TemplateMethod;
public
partial
class
TemplateMethod : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
AbstractMessageTemplate m = new XmlMessage("user");
Response.Write(m.TemplateMethodGet()[0].Message + " " + m.TemplateMethodGet()[0].PublishTime.ToString());
Response.Write("<br />");
m = new sqlMessage("admin");
Response.Write(m.TemplateMethodGet()[0].Message + " " + m.TemplateMethodGet()[0].PublishTime.ToString());
Response.Write("<br />");
}
}
运行结果
无权
获取 2007-3-13 22:29:55
sql方式
获取Message 2007-3-13 22:29:55
OK
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