判断是否为按钮单击事件触发的page_load

<form   runat=server>  
  <asp:Button   id="Button1"   Text="Button1"   runat=server   onclick="Button1_Click"   />   
    </form>  
  <script   language=C#   runat=server>  
   
  void   Page_Load(object   o,   EventArgs   e)  
  {  
    if   (IsPostBack)  
    {  
          if   (Request.Form[Button1.UniqueID]   !=   null)  
          {  
      Response.Write("Page_Load:   Button   1   clicked<BR>");  
          }   
    }  
  }  
   
  void   Button1_Click(Object   o,   EventArgs   e)  
  {  
      Response.Write("Button   1   clicked");  
  }   
        
  </script>

来源：https://www.cnblogs.com/WormCanFly/archive/2009/02/10/1387414.html