asp.net ListBox单选、全选、清除等功能

1：注意要得把两个listbox的selectectionmode属性设置为mutiple

2 后台代码：

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

public partial class TestListBox : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
           
            ListBox2Bind();
          
        }
    }

    private void ListBox2Bind()
    {
        string[] str = new string[] { "北京","上海","福建","广东","浙江" };
        for (int i = 0; i < str.Length - 1; i++)
        {
            ListBox2.Items.Add(str[i]);
        }

    }
    protected void btnAdd_Click(object sender, EventArgs e)
    {
        
        int count = ListBox2.Items.Count;
        int index = 0;
        for (int i = 0; i < count; i++)
        {
            ListItem item = ListBox2.Items[index];
            if (ListBox2.Items[index].Selected == true)
            {
                ListBox2.Items.Remove(item);
                ListBox3.Items.Add(item);
                index--;
            }
            index++;
        }
    }
    protected void btnDel_Click(object sender, EventArgs e)
    {
        int count = ListBox3.Items.Count;
        int index = 0;
        for (int i = 0; i < count; i++)
        {
            ListItem item = ListBox3.Items[index];
            if (ListBox3.Items[index].Selected == true)
            {
                ListBox3.Items.Remove(item);
                ListBox2.Items.Add(item);
                index--;
            }
            index++;
        }

    }
    protected void AddAll_Click(object sender, EventArgs e)
    {
        int count = ListBox2.Items.Count;
        int index = 0;
        for (int i = 0; i < count; i++)
        {
            ListItem item = ListBox2.Items[index];
            ListBox2.Items.Remove(item);
            ListBox3.Items.Add(item);
        }
        index++;
    }
    protected void DelAll_Click(object sender, EventArgs e)
    {
        int count = ListBox3.Items.Count;
        int index = 0;
        for (int i = 0; i < count; i++)
        {
            ListItem item = ListBox3.Items[index];
            ListBox3.Items.Remove(item);
            ListBox2.Items.Add(item);
        }
        index++;
    }
}

　3：效果图