嵌套的UpdatePanel

     < form id = " form1 "  runat = " server " >
         < asp:ScriptManager ID = " ScriptManager1 "  runat = " server " >
         </ asp:ScriptManager >

     < asp:UpdatePanel ID = " UpdatePanel1 "  runat = " server "  UpdateMode = " Conditional " >
         < ContentTemplate >
             <%=  DateTime.Now  %>
             < asp:UpdatePanel ID = " UpdatePanel2 "  runat = " server " >
                 < ContentTemplate >
                     <%=  DateTime.Now  %>
                     < asp:Button ID = " Button1 "  runat = " server "  Text = " Button "   />
                 </ ContentTemplate >
             </ asp:UpdatePanel >
         </ ContentTemplate >
     </ asp:UpdatePanel >

     </ form >

点击 Button1按钮，只有 UpdatePanel2里面的时间会更新，而 UpdatePanel1中的时间不会更新，当前套 UpdatePanel时，里面的UpdatePanel的控件回发不会引起外面一层的UpdatePanel更新