自定义复合控件[2]-引发缓存事件

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

namespace  csMathControl
{
     ///   <summary>
     ///  引发缓存事件
     ///   </summary>
    [DefaultProperty( " Text " ), 
        ToolboxData( " <{0}:RenderText runat=server></{0}:RenderText> " )]
     public   class  RenderText : System.Web.UI.WebControls.WebControl
    {
        
        [Bindable( true ), 
            Category( " Appearance " ), 
            DefaultValue( "" )] 
         public   string  Text 
        {
             get
            {
                 if (ViewState[ " text " ] != null )
                 return  ViewState[ " text " ].ToString();
                 else
                     return   null ;
            }
             set
            {
                ViewState[ " text " ]  =  value;
                OnChange(EventArgs.Empty);
            }
        }
         ///   <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.RenderBeginTag( " INPUT " );
            output.RenderEndTag();
        }
         // ---------------事件--------------------
         ///
         public   event  EventHandler Change;
         protected   virtual   void  OnChange(EventArgs e)
        {
             if (Change != null )
                Change( this ,e);
        }
         // ----------------------------------
    }
}