ASP.NET 动态创建TextBox 以及取值问题

<asp:Panel ID="Panel1" runat="server">  

<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

<br />  

<asp:Button ID="Button2" runat="server" onclick="Button2_Click" Text="Button2" />  

<asp:TextBox ID="TextBox1" runat="server">

protected void Page_Load(object sender, EventArgs e) {

}

protected void Page_Init(object sender, EventArgs e) {  

TextBox t1 = new TextBox(); t1.ID = "TextBox2";

TextBox t2 = new TextBox(); t2.ID = "TextBox3";

t1.EnableViewState = true;

t2.EnableViewState = true;

t1.ViewStateMode = ViewStateMode.Enabled;

t2.ViewStateMode = ViewStateMode.Enabled;

Panel1.Controls.Add(t1); Panel1.Controls.Add(t2);

t1.Visible = false;

t2.Visible = false; }

protected void Button1_Click(object sender, EventArgs e) { 

TextBox t1 = (TextBox)Panel1.FindControl("TextBox2");

TextBox t2 = (TextBox)Panel1.FindControl("TextBox3");

t1.Visible = true;

t2.Visible = true;

}

protected void Button2_Click(object sender, EventArgs e) {  

 TextBox t1 = (TextBox)Panel1.FindControl("TextBox2");

TextBox t2 = (TextBox)Panel1.FindControl("TextBox3");

String a =t1.Text.ToString();

String b =t2.Text.ToString();

}

点击button1后页面出现事先定义好的textbox

点击button2把textbox内填入的值取回