将GridView内数据导入到Excel

以下是导出数据的后台类：

using System;
using System.Data;
using System.Data.SqlClient;
using System.IO;

namespace WebUtility
...{
    /**//// <summary>
    /// 将Table的数据导出Excel;
    /// 标题为Table的标题;
    /// 使用文件操作来完成此功能:
    /// 缺点:不能操作Excel;标题可能是英文,没有边框,没有格式;
    /// </summary>
    public class OutExcel:DBUtility.DBHelper
    ...{
        /**//// <summary>
        /// 导出EXCEL
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="FileName"></param>
        /// <returns></returns>
        public int Export(DataTable dt,string FileName)
        ...{
            try
            ...{
                //文件名;创建;可写
                FileStream fs=new FileStream(FileName,FileMode.Create,FileAccess.Write); 
                StreamWriter sw=new StreamWriter(fs,System.Text.Encoding.GetEncoding("gb2312"));
                //标题
                string Title = "";
                //内容
                string Line = "";
                for (int i=0;i<dt.Columns.Count;i++)
                ...{
                    Title = Title + dt.Columns[i].ToString() + " ";
                }
                //去掉最后的回车符
                Title = Title.Substring(0,Title.Length -1);
                //将标题写入流
                sw.WriteLine(Title); 
                foreach(DataRow dr in dt.Rows) 
                ...{ 
                    for (int i=0;i<dt.Columns.Count;i++)
                    ...{
                        Line = Line+dr[i] + " ";
                    }
                    Line = Line.Substring(0,Line.Length -1);
                    //将数据写入文件流
                    sw.WriteLine(Line); 
                    Line = "";
                } 
                sw.Close();
                return 0;
            }
            catch
            ...{
                return 1;
            }
        }
        //===============================================================================================
    }
}

 在页面上进行调用：

protected void btnOut_Click(object sender, EventArgs e)
    ...{
        public WebUtility.OutExcel myOut = new WebUtility.OutExcel();
        //导出日志到Excel
        System.Data.DataTable dt = user.DataSetLoginLog(WebUtility.SysUser.LoginLogType.all).Tables[0];
        string DownloadPath = Server.MapPath(".") + "//" + string.Format("登录日志备份{0}.XLS",System.DateTime.Now.ToShortDateString());
        //导出
        this.myOut.Export(dt, DownloadPath);
        //以下代码将 pdf 文件写入客户端浏览器。
        Response.ClearContent();
        Response.ClearHeaders();
        //作为附件下载
        Response.AddHeader("Content-Disposition", "attachment; filename=" + Server.UrlEncode(DownloadPath));
        Response.ContentType = "application/ms-excel";
        Response.WriteFile(DownloadPath);
        Response.Flush();
        Response.Close();
        //从磁盘删除导出的文件
        System.IO.File.Delete(DownloadPath);
    }