设计模式 - State Pattern(状态模式)
[源码下载]
设计模式 - State Pattern(状态模式)
作者：webabcd 介绍 允许一个对象在其内部状态改变时改变它的行为。对象看起来似乎修改了它所属的类。 示例 有一个Message实体类，对它的操作有Insert()和Get()方法，持久化数据在sqlServer数据库中或Xml文件里。在对象内部可以根据用户的不同选择不同的数据持久化方案。
MessageModel
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.State
{
/**//// <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; }
}
}
}
AbstractMessageState
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.State
{
/**//// <summary>
/// 状态模式抽象类
/// </summary>
public abstract class AbstractMessageState
{
/**//// <summary>
/// Context类型
/// </summary>
protected Message _message;
/**//// <summary>
/// Context类型属性
/// </summary>
public Message Message
{
get
{ return _message; }
set
{ _message = value; }
}
/**//// <summary>
/// 改变状态
/// </summary>
public abstract void StateChangeCheck();
/**//// <summary>
/// 获取Message
/// </summary>
/// <returns></returns>
public abstract List<MessageModel> Get();
/**//// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public abstract bool Insert(MessageModel mm);
}
}
XmlMessage
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.State
{
/**//// <summary>
/// Xml方式操作Message
/// </summary>
public class XmlMessage : AbstractMessageState
{
/**//// <summary>
/// 构造函数
/// </summary>
/// <param name="message">Context类型参数</param>
public XmlMessage(Message message)
{
this._message = message;
}
/**//// <summary>
/// 改变状态
/// </summary>
public override void StateChangeCheck()
{
// 如果UserId是admin则变换状态为sqlMessage
if (this._message.UserId == "admin")
{
this._message.AbstractMessageState = new sqlMessage(this._message);
}
}
/**//// <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;
}
/**//// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public override bool Insert(MessageModel mm)
{
// 代码略
return true;
}
}
}
sqlMessage
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.State
{
/**//// <summary>
/// sql方式操作Message
/// </summary>
public class sqlMessage : AbstractMessageState
{
/**//// <summary>
/// 构造函数
/// </summary>
/// <param name="message">Context类型参数</param>
public sqlMessage(Message message)
{
this._message = message;
}
/**//// <summary>
/// 改变状态
/// </summary>
public override void StateChangeCheck()
{
}
/**//// <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;
}
/**//// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public override bool Insert(MessageModel mm)
{
// 代码略
return true;
}
}
}
Message
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Pattern.State
{
/**//// <summary>
/// Context类
/// </summary>
public class Message
{
/**//// <summary>
/// 类型为状态模式抽象类的私有变量
/// </summary>
private AbstractMessageState _abstractMessageState;
/**//// <summary>
/// 类型为状态模式抽象类的属性
/// </summary>
public AbstractMessageState AbstractMessageState
{
get
{ return _abstractMessageState; }
set
{ _abstractMessageState = value; }
}
/**//// <summary>
/// UserId私有变量
/// </summary>
private string _userId;
/**//// <summary>
/// UserId
/// </summary>
public string UserId
{
get
{ return _userId; }
set
{ _userId = value; }
}
/**//// <summary>
/// 构造函数
/// </summary>
/// <param name="userId">UserId</param>
public Message(string userId)
{
this._userId = userId;
_abstractMessageState = new XmlMessage(this);
}
/**//// <summary>
/// 获取Message
/// </summary>
/// <returns></returns>
public List<MessageModel> Get()
{
// 修改状态
_abstractMessageState.StateChangeCheck();
return _abstractMessageState.Get();
}
/**//// <summary>
/// 插入Message
/// </summary>
/// <param name="mm">Message实体对象</param>
/// <returns></returns>
public bool Insert(MessageModel mm)
{
// 修改状态
_abstractMessageState.StateChangeCheck();
return _abstractMessageState.Insert(mm);
}
}
}
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.State;
public
partial
class
State : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Message m = new Message("admin");
Response.Write(m.Insert(new MessageModel("插入", DateTime.Now)));
Response.Write("<br />");
Response.Write(m.Get()[0].Message + " " + m.Get()[0].PublishTime.ToString());
Response.Write("<br />");
m = new Message("user");
Response.Write(m.Insert(new MessageModel("插入", DateTime.Now)));
Response.Write("<br />");
Response.Write(m.Get()[0].Message + " " + m.Get()[0].PublishTime.ToString());
Response.Write("<br />");
}
}
运行结果 True sql方式获取Message 2007-3-6 22:58:17 True XML方式获取Message 2007-3-6 22:58:17 OK [源码下载]
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