Question

我开始.net并开始我将动态创建多个文本框。

我写了这个：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Page sans titre</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="Button1" runat="server" Text="Button" onclick="OnclickButton" />
    </div>
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <br />
    </form>
</body>
</html>

和这个

namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {    
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void OnclickButton(object sender, EventArgs ea)
        {
            Random random = new Random();
            int randomNumber = random.Next(0, 100);

            Button btnSomeButton = sender as Button;
            btnSomeButton.Text = "I was clicked!" + randomNumber;

            TextBox txt = new TextBox();
            txt.ID = "txt_" + randomNumber;
            form1.Controls.Add(txt);
        }    
    }
}

我不明白为什么当我在Button1上单击2次时，只出现1个文本框。

为什么会这样？做我想要的好方法是什么？提前谢谢你

Answer 1

每次点击按钮都会回复。请阅读postbacks

系统一次只能处理一次回发。它需要等待回发返回才能处理另一个动作。

另请阅读Page lifecycle enter image description here

Answer 2

Web状态较少。换句话说，服务器不知道有多少控件是动态添加的，除非您存储信息以便在回发后保留。

因此，您希望将数据保存到 ViewState（或SessionState） ，然后使用相同的ID重新加载 < / strong>在帖子后面。

<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click"/> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> private List<int> ControlIds { get { return (List<int>) ViewState["ControlIds"] ?? new List<int>(); } set { ViewState["ControlIds"] = value; } } protected void Page_Load(object sender, EventArgs e) { if (IsPostBack) { // Reload the controls on post back var ids = ControlIds; foreach (var id in ids) { var txt = new TextBox {ID = "txt_" + id}; form1.Controls.Add(txt); } } } protected void Button1_Click(object sender, EventArgs e) { var random = new Random(); int randomNumber = random.Next(0, 100); var ids = ControlIds; if (ids.Contains(randomNumber)) { // Randam number already exists. // We cannot add controls with same ID. return; } ids.Add(randomNumber); ControlIds = ids; var btnSomeButton = sender as Button; btnSomeButton.Text = "I was clicked!" + randomNumber; var txt = new TextBox { ID = "txt_" + randomNumber, Text = randomNumber.ToString() // Just for testing }; form1.Controls.Add(txt); }

添加多个文本框.net

2 个答案: