ASP.NET 页面生命周期-动态控件编程（动态添加控件并使用动态控件值）

当页面进行回发时，如点击按钮，事件会按一下顺序执行：

1. OnPreInit
2. OnInit
3. OnInitComplete
4. OnPreLoad
5. Page_Load
6. OnLoad
7. Button_Click
8. OnLoadComplete
9. OnPreRender

这里只做Page_Load和Button_Click的例子来实现页面动态添加控件并使用动态控件的值

首先编写一个页面：

<div style="900px;  margin:auto"  >
        <asp:TextBox ID="TextBox3" runat="server" ></asp:TextBox>
        <asp:Button ID="Button4" runat="server"   Text="添加到动物" OnClick="Button4_Click1" />
            
        <asp:Button ID="Button5" runat="server" Text="添加到食物" OnClick="Button5_Click1" />
        <div  id="div_big" runat="server"  style=" 750px; height: 70px; padding: 10px; margin-top: 0px;">
            <div id="div_animal"  style=" 250px; float: left; height: 30px; padding: 10px">
                <asp:Label ID="Label1" runat="server" Text="动物："></asp:Label>
                <asp:DropDownList ID="DropDownList2" runat="server">
                    <asp:ListItem>狗</asp:ListItem>
                </asp:DropDownList>
            </div >
            <div id="div_food" runat="server"  style=" 459px; height: 30px; padding: 10px">
                <asp:Label ID="Label2" runat="server" Text="食物："></asp:Label>
            </div>
        </div>
        <div style=" 750px;  height: 40px; padding:10px ;text-align:center" >
        <asp:Button ID="Button6" runat="server" Text="提交" OnClick="Button6_Click1" Width="100px" Height="37px"  />
            </div>
        <asp:TextBox ID="TextBox4" runat="server" Width="763px" Height="36px"  ></asp:TextBox>
        <br />
        <asp:TextBox ID="TextBox5" runat="server" Width="762px" Height="36px"   Visible="false"></asp:TextBox>
            </div>

效果图：

从上端文本框中输入相应的值后点击“添加到动物”或“添加到食物”会将数据动态的添加到页面中，点击“提交”来动态的获取其中的值。

效果：

后台代码实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default2 : System.Web.UI.Page
{

    CheckBox ch;
    
    protected void Page_Load(object sender, EventArgs e)
    {   
        for (int h = 0; h < div_food.Controls.Count;h++ ) {
            if (div_food.Controls[i] is CheckBox ) {
                div_food.Controls.RemoveAt(i);
            }
        }
        if (TextBox5.Text != "")
        {
            string[] ary = TextBox5.Text.Split(',');
            for(int s=0;s<ary.Length;s++){
                ch = new CheckBox();
                ch.Text = ary[s];
                if (ch.Text != "")
                {
                    div_food.Controls.Add(ch);
                }
        }
            }
    }
   
    protected void Button4_Click1(object sender, EventArgs e)
    {
        string str = TextBox3.Text;
        ListItem item = new ListItem();
        item.Text = str;
        item.Value = str;
        DropDownList2.Items.Add(item);
        TextBox3.Text = "";
    }
    protected void Button5_Click1(object sender, EventArgs e)
    {
      if(TextBox3.Text!=""){
          ch=new CheckBox();
          ch.Text = TextBox3.Text;
          div_food.Controls.Add(ch);
          TextBox5.Text += TextBox3.Text + ",";
      }
      TextBox3.Text = ""; 
    }
    protected void Button6_Click1(object sender, EventArgs e)
    {
        string str = "";
        
        CheckBox tt;
        foreach (Control cc in div_food.Controls )
        {
            if (cc is CheckBox)
            {
                tt = (CheckBox)cc;
                if (tt.Checked)
                {
                    str += tt.Text + "、";
                }
            }
        }
        if (str == "") {
            str = "还没有选择食物！";
        }
        TextBox4.Text = DropDownList2.Text + "所喜欢的食物是：" + str;
    }
}

站在巨人的肩膀上真的会看的更远更清晰！

　　　　　　　　　　　　　　　　　　　　　　　　　　　-----用志不分，乃凝于神