ASP.NET中使用多个runat=server form

ASP.NET 在同一个页面不支持多个 runat=server forms，要解决这个问题，可以把每个 form 放在一个单独的 panel 控件中，这样用户就可以简单地通过单选按钮在不同 panel 间切换。
代码如下：
2FormExample.aspx

<%@ Page language="c#" Codebehind="2FormExample.cs" AutoEventWireup="false"
Inherits="_3leaf_app.C2FormExample" %>
<html><head>
<meta name=vs_targetSchema content="HTML 4.0">
<meta name="GENERATOR" Content="Microsoft Visual Studio 7.0">
<meta name="CODE_LANGUAGE" Content="C#"></head>
<body>

<form method="post" runat="server" ID=Form1>
    <p>Lookup by
    <asp:RadioButton id=RadioButton1 runat="server" Text="First Name" AutoPostBack="True"  groupname=g1
checked=True></asp:RadioButton>
    <asp:RadioButton id=RadioButton2 runat="server" Text="Last Name" AutoPostBack="True"
groupname=g1></asp:RadioButton></p>
    <p></p>
    <p>
    <asp:Panel id=Panel1 runat="server" visible=True>
        First Name :
        <asp:TextBox id=TextBox1 runat="server"></asp:TextBox>
        <asp:RequiredFieldValidator id=RequiredFieldValidator1 runat="server" ErrorMessage="*"
ControlToValidate="TextBox1"></asp:RequiredFieldValidator>
        <asp:Button id=Button1 runat="server" Text="Submit"></asp:Button>
    </asp:Panel>
    <asp:Panel id=Panel2 runat="server" visible=False>
        Last Name :
        <asp:TextBox id=TextBox2 runat="server"></asp:TextBox>
        <asp:RequiredFieldValidator id=RequiredFieldValidator2 runat="server" ErrorMessage="*"
ControlToValidate="TextBox2"></asp:RequiredFieldValidator>
        <asp:Button id=Button2 runat="server" Text="Submit"></asp:Button>
    </asp:Panel>
    <p></p>
    <p>
        <asp:label id=Label1 runat="server"></asp:label>
    </p>
</form>

</body></html>

2FormExample.cs

namespace _3leaf_app
{
    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Web;
    using System.Web.SessionState;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.HtmlControls;

    /// <summary>
    ///    Summary description for C2FormExample.
    /// </summary>
    public class C2FormExample : System.Web.UI.Page
    {
  protected System.Web.UI.WebControls.Button Button2;
  protected System.Web.UI.WebControls.RequiredFieldValidator RequiredFieldValidator2;
  protected System.Web.UI.WebControls.TextBox TextBox2;
  protected System.Web.UI.WebControls.Button Button1;
  protected System.Web.UI.WebControls.RequiredFieldValidator RequiredFieldValidator1;
  protected System.Web.UI.WebControls.TextBox TextBox1;
  protected System.Web.UI.WebControls.Label Label1;
  protected System.Web.UI.WebControls.Panel Panel2;
  protected System.Web.UI.WebControls.Panel Panel1;
  protected System.Web.UI.WebControls.RadioButton RadioButton2;
  protected System.Web.UI.WebControls.RadioButton RadioButton1;

    public C2FormExample()
    {
        Page.Init += new System.EventHandler(Page_Init);
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
            }
        }

        protected void Page_Init(object sender, EventArgs e)
        {
            //
            // CODEGEN: This call is required by the ASP+ Windows Form Designer.
            //
            InitializeComponent();
        }

        /// <summary>
        ///    Required method for Designer support - do not modify
        ///    the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
  {
   RadioButton1.CheckedChanged += new System.EventHandler (this.RadioButton1_CheckedChanged);
   Button1.Click += new System.EventHandler (this.Button1_Click);
   RadioButton2.CheckedChanged += new System.EventHandler (this.RadioButton2_CheckedChanged);
   Button2.Click += new System.EventHandler (this.Button2_Click);
   this.Load += new System.EventHandler (this.Page_Load);
  }

        public void Button2_Click (object sender, System.EventArgs e)
        {
            Label1.Text = "You want to search on last name";
        }

        public void Button1_Click (object sender, System.EventArgs e)
        {
            Label1.Text = "You want to search on first name";
        }

        public void RadioButton2_CheckedChanged (object sender, System.EventArgs e)
        {
            Panel1.Visible = false;
            Panel2.Visible = true;
        }

        public void RadioButton1_CheckedChanged (object sender, System.EventArgs e)
        {
            Panel1.Visible = true;
            Panel2.Visible = false;
        }
    }
}