20151215：练习：全选

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            TextDataContext context = new TextDataContext();
            CheckBoxList1.DataSource = context.Nation;
            CheckBoxList1.DataTextField = "Name";
            CheckBoxList1.DataValueField = "Code";
            CheckBoxList1.DataBind();
        }
    }
    protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
    {
        //设置点击全选和取消全选
        foreach( ListItem item in CheckBoxList1.Items )
        {
            item.Selected = CheckBox1.Checked;
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        //取值
        string zhi = "";
        foreach( ListItem item in CheckBoxList1.Items )
        {
            if(item.Selected)
            {
                zhi += item.Value.ToString()+",";//用，分割
            }
        }
        //去掉最后多余的逗号
        zhi = zhi.Substring(0, zhi.Length - 1);
        //拆分字符串,把选中的每一项都弹出一个窗体
        string[] codes;
        codes = zhi.Split(‘,‘);
        //造js代码
        string js = "<script type=‘text/javascript‘>";

        for (int i = 0; i < codes.Length; i++)
        {
            js += "alert(‘"+codes[i]+"‘);";
        }

        js += "</script>";

        Literal1.Text = js;
            //弹出一个窗体，显示选中的值，借助一个工具Literall，在Literall中写js代码
            //Literal1.Text = "<script type=‘text/javascript‘>alert(‘" + zhi + "‘)</script>";

    }