如何在ASP.NET Web应用程序中显示错误消息

protected void Button1_Click(object sender, EventArgs e)
{
    try
    {
        // 执行可能引发异常的代码
    }
    catch (Exception ex)
    {
        Response.Write("<font color='red'>错误消息：" + ex.Message + "</font>");
    }
}

<asp:Label ID="ErrorLabel" runat="server" ForeColor="Red" Visible="False"></asp:Label>

protected void Button1_Click(object sender, EventArgs e)
{
    try
    {
        // 执行可能引发异常的代码
    }
    catch (Exception ex)
    {
        ErrorLabel.Text = "错误消息：" + ex.Message;
        ErrorLabel.Visible = true;
    }
}

<asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="错误消息" OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator>

protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
{
    try
    {
        // 执行可能引发异常的代码
        args.IsValid = true;
    }
    catch (Exception ex)
    {
        CustomValidator1.ErrorMessage = "错误消息：" + ex.Message;
        args.IsValid = false;
    }
}

<asp:ValidationSummary ID="ValidationSummary1" runat="server" ForeColor="Red" />

protected void Button1_Click(object sender, EventArgs e)
{
    try
    {
        // 执行可能引发异常的代码
    }
    catch (Exception ex)
    {
        ValidationSummary1.AddError("错误消息：" + ex.Message);
    }
}