三.Bridge Pattern(橋接模式)

<% @ Page Language = " C# "  AutoEventWireup = " true "  CodeFile = " Bridge Pattern.aspx.cs "  Inherits = " Pattern_Bridge_Pattern "   %>

< html  xmlns ="http://www.w3.org/1999/xhtml"   >
< head  runat ="server" >
     < title > Bridge Pattern </ title >
</ head >
< body >
     < form  id ="form1"  runat ="server" >
     < div >
         < asp:TextBox  ID ="tb_result"  runat ="server"  TextMode ="MultiLine"  Rows ="5" ></ asp:TextBox >
         < asp:Button  ID ="bt_submit"  runat ="server"  OnClick ="bt_submit_Click"   Text ="BridgePattern"   />     
         < select  id ="strategy_select"  runat ="server" >
             < option  value ="A"  selected ="selected" > A </ option >
             < option  value ="B" > B </ option >             
         </ select >
     </ div >
     </ form >
</ body >
</ html >

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;

///   <summary>
///  優點: 將動作抽象和動作實現層分離,是兩者可以獨立的變化,体現靈活性.
///   </summary>
public  partial  class  Pattern_Bridge_Pattern : System.Web.UI.Page
{
     protected   void  Page_Load( object  sender, EventArgs e)
    {
    }

     protected   void  bt_submit_Click( object  sender, EventArgs e)
    {
        BridgeResult();
    }

     public   void  BridgeResult()
    {
        AbstractClass abclass  =   new  RefinedAbstractClass();
         switch  (strategy_select.Items[strategy_select.SelectedIndex].Value.ToString())
        {

             case   " A " :
                abclass.MyFields  =   new  ConcrateA();                
                 break ;
             case   " B " :
                abclass.MyFields  =   new  ConcrateB();               
                 break ;            
             default :
                abclass.MyFields  =   new  ConcrateB();
                 break ;
        }
        tb_result.Text  =  abclass.Action();
    }
}

///   <summary>
///  定義抽象動作
///   </summary>
abstract   class  Fields
{
     abstract   public   string  Action();
}

class  AbstractClass
{
     protected  Fields fields;
     public  Fields MyFields
    {
         set  { fields  =  value; }
    }
     virtual   public   string  Action()
    {
         return  fields.Action();
    }
}

class  RefinedAbstractClass : AbstractClass
{
     public   override   string  Action()
    {
         return  fields.Action();
    }
}

///   <summary>
///  具體動作類
///   </summary>
class  ConcrateA : Fields
{
     public   override   string  Action()
    {
         return   " A " ;
    }
}

class  ConcrateB : Fields
{
     public   override   string  Action()
    {
         return   " B " ;
    }
}