<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="FileUpload1"
ErrorMessage="必须是 jpg或者gif文件" ValidationExpression="^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.jpg|.Jpg|.gif|.Gif)$"></asp:RegularExpressionValidator>
转载于:https://www.cnblogs.com/z2002m/archive/2008/07/03/1234473.html