自定义复合控件[3]获取客户信息

using  System;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.ComponentModel;

namespace  csMathControl
{
     ///   <summary>
     ///  从客户端获取数据
     ///   </summary>
    [DefaultProperty( " Text " ), 
        ToolboxData( " <{0}:RenderPostBackText runat=server></{0}:RenderPostBackText> " )]
    [DefaultEvent( " Change " )]
     public   class  RenderPostBackText : System.Web.UI.WebControls.WebControl,IPostBackDataHandler
    {    
        [Bindable( true ), 
            Category( " Appearance " ), 
            DefaultValue( "" )] 
         public   string  Text 
        {
             get
            {
                 if (ViewState[ " text " ] != null )
                 return  ViewState[ " text " ].ToString();
                 else
                     return   null ;
            }

             set
            {
                ViewState[ " text " ] = value;
                
            }
        }
         ///   <summary>  
         ///  将此控件呈现给指定的输出参数。
         ///   </summary>
         ///   <param name="output">  要写出到的 HTML 编写器  </param>
         protected   override   void  Render(HtmlTextWriter output)
        {
             // output.Write(Text);
            output.AddAttribute( " value " , this .Text );
            output.AddAttribute( " name " , this .UniqueID); // [2]必须将这个属性定义成允许使用回递数据
            output.RenderBeginTag( " INPUT " );
            output.RenderEndTag();
        }
         public   event  EventHandler Change;
         protected   virtual   void  OnChange(EventArgs e)
        {
             if (Change != null )
                Change( this ,e);
        }
         #region  IPostBackDataHandler 成员

         public   void  RaisePostDataChangedEvent()
        {
             //  TODO:  添加 RenderPostBackText.RaisePostDataChangedEvent 实现
            OnChange(EventArgs.Empty);
        }

         public   bool  LoadPostData( string  postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
        {
             //  TODO:  添加 RenderPostBackText.LoadPostData 实现
             // return false;
             // 如果用户该便了文本就更新文本属性
             if ( this .Text != postCollection[postDataKey])
            {
                 this .Text = postCollection[postDataKey];
                 // 返回true就会调用上面的RaisePostDataChangeEvent
                 return   true ;

            }
             else
                 return   false ;
        }

         #endregion
    }
}