.net 手动导出excel

private StringWriter GetStringWriter(DataTable dt)
    {
        StringWriter sw = new StringWriter();
        //读列名
        foreach (DataColumn dc in dt.Columns)
            sw.Write(dc.ColumnName + "\t");

        //读列值
        //重新的一行
        sw.Write(sw.NewLine);
        if (dt != null)
        {
            foreach (DataRow dr in dt.Rows)
            {
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    sw.Write(dr[i].ToString() + "\t");
                }
                sw.Write(sw.NewLine);
            }
        }
        sw.Close();

        return sw;
    }

    protected void ExcelImport(DataTable dt, string ExportFileName)
    {
        StringWriter sw = GetStringWriter(dt);
        //当前编码
        HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
        //把输出的文件名进行编码
        string fileName = HttpUtility.UrlEncode(ExportFileName, System.Text.Encoding.UTF8);
        //文件名
        string str = "attachment;filename=" + fileName + ".xls";
        //  sw.ContentType = "application/vnd.ms-excel";
        //把文件头输出，此文件头激活文件下载框
        HttpContext.Current.Response.AppendHeader("Content-Disposition", str);//http报头文件
        HttpContext.Current.Response.ContentType = "application/ms-excel";
        this.Page.EnableViewState = false;

        Response.Write(sw);
        Response.End();
    }