ASP.net指定框架显示

 <form id="form1" runat="server" >
    <div>
    <asp:TextBox ID="Txt1" runat="server"></asp:TextBox>
       
        <input type="button" name="Button1" value="test" onclick="document.forms[0].target='frame1' ;document.forms[0].action='testiframe.aspx'; document.forms[0].submit();" />
        <iframe id="frame1"  name ="frame1"  src =testiframe.aspx ></iframe>
    </div>
   
    </form>

testiframe.aspx

protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.Form["Txt1"] != null)
        {
            string str = Request.Form["Txt1"].ToString();
            Response.Write(str);
        }
    }