FileUpload

           <asp:FileUpload ID="FileUpload1" runat="server" />             <input type = "submit" name = "Submit" value = "Submit" id="Submit1" runat="server" onserverclick="Submit1_ServerClick"/><!--onclick="return Submit1_onclick()"/-->
        protected void Submit1_ServerClick(object sender, EventArgs e)
        {
             if (FileUpload1.HasFile) {//这里显示是false，为什么呀？
        FileInfo file = new FileInfo (FileUpload1.PostedFile.FileName);
        FileUpload1.SaveAs(Server.MapPath("~/runtime/" + file.Name));
    }