[索引页]
[源码下载]
作者： webabcd
介绍
在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可将该对象恢复到保存的状态。
示例
有一个Message实体类，某个对象对它的操作有Insert()方法，只有在插入时间符合要求的情况下才能插入成功，因此要求可以保存和恢复Message对象的状态，插入失败后则恢复Message对象的状态，然后只更新时间，再次插入。
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Message实体类（Memento）
/// </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; }
}
}
}
MessageModelCaretaker
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Memento管理者（Caretaker）
/// </summary>
public
class MessageModelCaretaker
{
private MessageModel _messageModel;
/// <summary>
/// Message实体对象（Memento）
/// </summary>
public MessageModel MessageModel
{
get {
return _messageModel; }
set { _messageModel = value; }
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Sql方式操作Message（Originator）
/// </summary>
public
class SqlMessage
{
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; }
}
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
bool Insert(MessageModel mm)
{
// 秒数可以被5整除时，则执行插入操作
if (mm.PublishTime.Second % 5 == 0)
{
// 代码略
return
true;
}
else
{
return
false;
}
}
/// <summary>
/// 保存Memento
/// </summary>
/// <returns></returns>
public MessageModel SaveMemento()
{
return
new MessageModel(_message, _publishTime);
}
/// <summary>
/// 恢复Memento
/// </summary>
/// <param name="mm"></param>
public
void RestoreMemento(MessageModel mm)
{
this._message = mm.Message;
this._publishTime = mm.PublishTime;
}
}
}
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.Memento;
public partial
class Memento : System.Web.UI.Page
{
protected
void Page_Load(
object sender, EventArgs e)
{
SqlMessage m =
new SqlMessage();
m.Message =
"Message内容";
m.PublishTime = DateTime.Now;
MessageModelCaretaker mmc =
new MessageModelCaretaker();
mmc.MessageModel = m.SaveMemento();
bool bln =
false;
while (!bln)
{
bln = m.Insert(
new MessageModel(m.Message, m.PublishTime));
Response.Write(m.Message +
" " + m.PublishTime.ToString() +
" " + bln.ToString());
Response.Write(
"<br />");
if (!bln)
{
System.Threading.Thread.Sleep(1000);
m.RestoreMemento(mmc.MessageModel);
m.PublishTime = DateTime.Now;
}
}
}
}
[源码下载]
乐在其中设计模式(C#) - 备忘录模式(Memento Pattern)
作者： webabcd
介绍
在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可将该对象恢复到保存的状态。
示例
有一个Message实体类，某个对象对它的操作有Insert()方法，只有在插入时间符合要求的情况下才能插入成功，因此要求可以保存和恢复Message对象的状态，插入失败后则恢复Message对象的状态，然后只更新时间，再次插入。
MessageModel
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Message实体类（Memento）
/// </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; }
}
}
}
MessageModelCaretaker
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Memento管理者（Caretaker）
/// </summary>
public
class MessageModelCaretaker
{
private MessageModel _messageModel;
/// <summary>
/// Message实体对象（Memento）
/// </summary>
public MessageModel MessageModel
{
get {
return _messageModel; }
set { _messageModel = value; }
}
}
}
SqlMessage
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Memento
{
/// <summary>
/// Sql方式操作Message（Originator）
/// </summary>
public
class SqlMessage
{
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; }
}
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
bool Insert(MessageModel mm)
{
// 秒数可以被5整除时，则执行插入操作
if (mm.PublishTime.Second % 5 == 0)
{
// 代码略
return
true;
}
else
{
return
false;
}
}
/// <summary>
/// 保存Memento
/// </summary>
/// <returns></returns>
public MessageModel SaveMemento()
{
return
new MessageModel(_message, _publishTime);
}
/// <summary>
/// 恢复Memento
/// </summary>
/// <param name="mm"></param>
public
void RestoreMemento(MessageModel mm)
{
this._message = mm.Message;
this._publishTime = mm.PublishTime;
}
}
}
Test
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.Memento;
public partial
class Memento : System.Web.UI.Page
{
protected
void Page_Load(
object sender, EventArgs e)
{
SqlMessage m =
new SqlMessage();
m.Message =
"Message内容";
m.PublishTime = DateTime.Now;
MessageModelCaretaker mmc =
new MessageModelCaretaker();
mmc.MessageModel = m.SaveMemento();
bool bln =
false;
while (!bln)
{
bln = m.Insert(
new MessageModel(m.Message, m.PublishTime));
Response.Write(m.Message +
" " + m.PublishTime.ToString() +
" " + bln.ToString());
Response.Write(
"<br />");
if (!bln)
{
System.Threading.Thread.Sleep(1000);
m.RestoreMemento(mmc.MessageModel);
m.PublishTime = DateTime.Now;
}
}
}
}
运行结果
Message内容 2007-5-23 21:32:13 False
Message内容 2007-5-23 21:32:14 False
Message内容 2007-5-23 21:32:15 True
参考
http://www.dofactory.com/Patterns/PatternMemento.aspx
OK
[源码下载]
Message内容 2007-5-23 21:32:13 False
Message内容 2007-5-23 21:32:14 False
Message内容 2007-5-23 21:32:15 True
参考
http://www.dofactory.com/Patterns/PatternMemento.aspx
OK
[源码下载]
本文转自webabcd 51CTO博客，原文链接：
http://blog.51cto.com/webabcd/344578
，如需转载请自行联系原作者
