[索引页]
[源码下载]
作者： webabcd
介绍
定义对象间的一种一对多的依赖关系,以便当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并自动刷新。
示例
有一个Message实体类，某些对象对它的操作有Insert()方法，当发生某些改变的时候，通知所有这些对象并执行Insert()方法。
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <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; }
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// 操作Message的接口（Observer）
/// </summary>
public
interface IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
string Insert(MessageModel mm);
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Sql方式操作Message（ConcreteObserver）
/// </summary>
public
class SqlMessage : IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
string Insert(MessageModel mm)
{
return
"sql方式：" + mm.Message +
" " + mm.PublishTime.ToString();
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Xml方式操作Message（ConcreteObserver）
/// </summary>
public
class XmlMessage : IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
string Insert(MessageModel mm)
{
return
"xml方式：" + mm.Message +
" " + mm.PublishTime.ToString();
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// 抽象Message主题（Subject）
/// </summary>
public
abstract
class AbstractMessageSubject
{
private MessageModel _messageModel;
private List<IMessage> list =
new List<IMessage>();
/// <summary>
/// 构造函数
/// </summary>
/// <param name="mm">Message实体对象</param>
public AbstractMessageSubject(MessageModel mm)
{
this._messageModel = mm;
}
/// <summary>
/// 添加一个实现IMessage接口的对象
/// </summary>
/// <param name="m">实现IMessage接口的对象</param>
public
void Attach(IMessage m)
{
list.Add(m);
}
/// <summary>
/// 移除一个实现IMessage接口的对象
/// </summary>
/// <param name="m">实现IMessage接口的对象</param>
public
void Detach(IMessage m)
{
list.Remove(m);
}
/// <summary>
/// 通知所有观察者
/// </summary>
/// <returns></returns>
public
string Notify()
{
string s = "";
foreach (IMessage i
in list)
{
s += i.Insert(_messageModel);
s +=
"<br />";
}
return s;
}
/// <summary>
/// Message发布时间
/// </summary>
public DateTime PublishTime
{
get {
return _messageModel.PublishTime; }
set
{
_messageModel.PublishTime = value;
Notify();
}
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Message主题（ConcreteSubject）
/// </summary>
public
class MessageSubject : AbstractMessageSubject
{
/// <summary>
/// 构造函数
/// </summary>
/// <param name="mm">Message实体对象</param>
public MessageSubject(MessageModel mm)
:
base(mm)
{
}
}
}
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.Observer;
public partial
class Observer : System.Web.UI.Page
{
protected
void Page_Load(
object sender, EventArgs e)
{
MessageSubject m =
new MessageSubject(
new MessageModel(
"插入Message", DateTime.Now));
SqlMessage sqlMessage =
new SqlMessage();
XmlMessage xmlMessage =
new XmlMessage();
m.Attach(sqlMessage);
m.Attach(xmlMessage);
// System.Threading.Thread.Sleep(1000);
// 修改了PublishTime就会通知所有观察者
// m.PublishTime = DateTime.Now;
Response.Write(m.Notify());
}
}
[源码下载]
乐在其中设计模式(C#) - 观察者模式(Observer Pattern)
作者： webabcd
介绍
定义对象间的一种一对多的依赖关系,以便当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并自动刷新。
示例
有一个Message实体类，某些对象对它的操作有Insert()方法，当发生某些改变的时候，通知所有这些对象并执行Insert()方法。
MessageModel
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <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; }
}
}
}
IMessage
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// 操作Message的接口（Observer）
/// </summary>
public
interface IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
string Insert(MessageModel mm);
}
}
SqlMessage
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Sql方式操作Message（ConcreteObserver）
/// </summary>
public
class SqlMessage : IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
string Insert(MessageModel mm)
{
return
"sql方式：" + mm.Message +
" " + mm.PublishTime.ToString();
}
}
}
XmlMessage
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Xml方式操作Message（ConcreteObserver）
/// </summary>
public
class XmlMessage : IMessage
{
/// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public
string Insert(MessageModel mm)
{
return
"xml方式：" + mm.Message +
" " + mm.PublishTime.ToString();
}
}
}
AbstractMessageSubject
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// 抽象Message主题（Subject）
/// </summary>
public
abstract
class AbstractMessageSubject
{
private MessageModel _messageModel;
private List<IMessage> list =
new List<IMessage>();
/// <summary>
/// 构造函数
/// </summary>
/// <param name="mm">Message实体对象</param>
public AbstractMessageSubject(MessageModel mm)
{
this._messageModel = mm;
}
/// <summary>
/// 添加一个实现IMessage接口的对象
/// </summary>
/// <param name="m">实现IMessage接口的对象</param>
public
void Attach(IMessage m)
{
list.Add(m);
}
/// <summary>
/// 移除一个实现IMessage接口的对象
/// </summary>
/// <param name="m">实现IMessage接口的对象</param>
public
void Detach(IMessage m)
{
list.Remove(m);
}
/// <summary>
/// 通知所有观察者
/// </summary>
/// <returns></returns>
public
string Notify()
{
string s = "";
foreach (IMessage i
in list)
{
s += i.Insert(_messageModel);
s +=
"<br />";
}
return s;
}
/// <summary>
/// Message发布时间
/// </summary>
public DateTime PublishTime
{
get {
return _messageModel.PublishTime; }
set
{
_messageModel.PublishTime = value;
Notify();
}
}
}
}
MessageSubject
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.Observer
{
/// <summary>
/// Message主题（ConcreteSubject）
/// </summary>
public
class MessageSubject : AbstractMessageSubject
{
/// <summary>
/// 构造函数
/// </summary>
/// <param name="mm">Message实体对象</param>
public MessageSubject(MessageModel mm)
:
base(mm)
{
}
}
}
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.Observer;
public partial
class Observer : System.Web.UI.Page
{
protected
void Page_Load(
object sender, EventArgs e)
{
MessageSubject m =
new MessageSubject(
new MessageModel(
"插入Message", DateTime.Now));
SqlMessage sqlMessage =
new SqlMessage();
XmlMessage xmlMessage =
new XmlMessage();
m.Attach(sqlMessage);
m.Attach(xmlMessage);
// System.Threading.Thread.Sleep(1000);
// 修改了PublishTime就会通知所有观察者
// m.PublishTime = DateTime.Now;
Response.Write(m.Notify());
}
}
运行结果
sql方式：插入Message 2007-5-26 9:38:18
xml方式：插入Message 2007-5-26 9:38:18
参考
http://www.dofactory.com/Patterns/PatternObserver.aspx
OK
[源码下载]
sql方式：插入Message 2007-5-26 9:38:18
xml方式：插入Message 2007-5-26 9:38:18
参考
http://www.dofactory.com/Patterns/PatternObserver.aspx
OK
[源码下载]
本文转自webabcd 51CTO博客，原文链接：
http://blog.51cto.com/webabcd/344584
，如需转载请自行联系原作者
