string Name;
        string Path;
        protected void Button2_Click(object sender, EventArgs e)
        {
            foreach (Control control in Panel1.Controls)
            {
                try
                {
                    if (((CheckBox)control).Checked)
                    {
                      //获取选择文件的相对路径。我将文件的相对路径写在了CssClass里面
                        Path = ((CheckBox)control).CssClass;
                        string[] path = Path.Split('/');
                        Name = path[path.Length - 1];
                        download(Path, Name);
                    }
                }
                catch (Exception)
                { continue; }
            }
        }

        private void download(string Path, string Name)
        {
            //用户下载文件时保存文件使用的默认命名
            string downLoadFileName = Name;
            //设定响应类型为下载
            this.Response.ContentType = "application/x-zip-compressed";
            //获取下载文件在服务器端的物理路径
            string downLoadPath = this.Server.MapPath(Path);

            //添加响应头标示信息  this.Server.UrlPathEncode对下载文件名进行编码 防止文件名乱码
            this.Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}", this.Server.UrlPathEncode(downLoadFileName)));
            //下载文件输出
            this.Response.TransmitFile(downLoadPath);
            this.Response.End();
        }