乐在其中设计模式(C#) - 外观模式(Facade Pattern)

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乐在其中设计模式(C#) - 外观模式(Facade Pattern)

作者： webabcd


介绍
为子系统中的一组接口提供一个一致的界面，Facade模式定义了一个高层接口，这个接口使得这一子系统更加容易使用。


示例
有一个Message实体类，某对象对它的操作有Get()方法，另外还有一个对象有一个Validate()方法来判断用户是否有权限。现在提供一个高层接口来封装这两个方法。

 

MessageModel

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Facade 
{ 
         /// <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; } 
                } 
        } 
}

 

User

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Facade 
{ 
         /// <summary> 
         /// 用户相关类 
         /// </summary> 
         public  class User 
        { 
                 /// <summary> 
                 /// 验证用户是否合法 
                 /// </summary> 
                 /// <param name="userId">UserId</param> 
                 /// <returns></returns> 
                 public  bool Validate( string userId) 
                { 
                         if (userId ==  "admin") 
                        { 
                                 return  true; 
                        } 
                         else 
                        { 
                                 return  false; 
                        } 
                } 
        } 
}

 

SqlMessage

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Facade 
{ 
         /// <summary> 
         /// Sql方式操作Message 
         /// </summary> 
         public  class SqlMessage 
        { 
                 /// <summary> 
                 /// 获取Message 
                 /// </summary> 
                 /// <returns></returns> 
                 public List<MessageModel> Get() 
                { 
                        List<MessageModel> l =  new List<MessageModel>(); 
                        l.Add( new MessageModel( "SQL方式获取Message", DateTime.Now)); 
 
                         return l; 
                } 
        } 
}

 

Message

using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Facade 
{ 
         /// <summary> 
         /// Facade类 
         /// </summary> 
         public  class Message 
        { 
                 private  string _userId = ""; 
 
                 /// <summary> 
                 /// 构造函数 
                 /// </summary> 
                 /// <param name="userId">UserId</param> 
                 public Message( string userId) 
                { 
                         this._userId = userId; 
                } 
 
                 /// <summary> 
                 /// 获取Message 
                 /// 首先使用User类的Validate()方法验证用户是否合法 
                 /// 然后使用SqlMessage类的Get()方法获取Message 
                 /// </summary> 
                 /// <returns></returns> 
                 public List<MessageModel> Get() 
                { 
                        User u =  new User(); 
                        SqlMessage m =  new SqlMessage(); 
 
                         if (u.Validate(_userId)) 
                        { 
                                 return m.Get(); 
                        } 
                         else 
                        { 
                                List<MessageModel> l =  new List<MessageModel>(); 
                                l.Add( new MessageModel( "无权获取", 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.Facade; 
 
public partial  class Facade : System.Web.UI.Page 
{ 
         protected  void Page_Load( object sender, EventArgs e) 
        { 
                Message m =  new Message( "user"); 
                Response.Write(m.Get()[0].Message +  " " + m.Get()[0].PublishTime.ToString()); 
                Response.Write( "<br />"); 
 
                m =  new Message( "admin"); 
                Response.Write(m.Get()[0].Message +  " " + m.Get()[0].PublishTime.ToString()); 
                Response.Write( "<br />"); 
        } 
}

 

 

运行结果
无权获取 2007-3-20 22:16:50
SQL方式获取Message 2007-3-20 22:16:50


参考
http://www.dofactory.com/Patterns/PatternFacade.aspx


OK
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     本文转自webabcd 51CTO博客，原文链接：http://blog.51cto.com/webabcd/344536 ，如需转载请自行联系原作者