TextBox1验证是否为空传统的

<asp:TextBox ID="TextBox1" runat="server" Height="51px" Width="161px" Rows="10" TextMode="MultiLine"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ForeColor="Red" text="用户名不能为空" ControlToValidate ="TextBox1" ></asp:RequiredFieldValidator>