支持 导入 导出Excel，导出Word， 导出PDF。

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using iTextSharp;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;
using System.Text;
using System.Data.OleDb;

using System.Collections.Generic;
using System.Linq;

namespace LinkPower.CivilAviation.Web.UICommon
{
    public class toDownLoad
    {
        private string strFileName = "";
        public toDownLoad(string _strFileName)
        {
            //
            //TODO: 在此处添加构造函数逻辑
            //
            strFileName = HttpUtility.UrlEncode(_strFileName.Trim(), System.Text.Encoding.UTF8) + DateTime.Now.ToString(@"_yyyyMMddhhmmss");
        }
        /// <summary>
        /// 导出Excel
        /// </summary>
        /// <param name="table">参数类型：DataTable</param>
        public void toExcel(DataTable table)
        {
            try
            {

                DataTable dt = new DataTable();
                dt = table;
                StringBuilder sb = new StringBuilder();
                sb.Append("<table cellspacing="0" cellpadding="5" rules="all" border="1">");
                sb.Append("<tr style="font-weight: bold; white-space: nowrap;">");
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    sb.Append("<td>").Append(dt.Columns[i].ColumnName).Append("</td>");
                }
                sb.Append("</tr>");

                foreach (DataRow row in dt.Rows)
                {
                    sb.Append("<tr>");
                    for (int i = 0; i < dt.Columns.Count; i++)
                    {
                        sb.Append("<td>").Append(row[i].ToString()).Append("</td>");
                    }
                    sb.Append("</tr>");
                }
                sb.Append("</table>");
                toResponse(sb.ToString(), "application/vnd.ms-excel", ".xls");
            }
            catch
            { }
        }
        /// <summary>
        /// 导出Word
        /// </summary>
        /// <param name="table">参数类型：DataTable</param>
        public void toWord(DataTable table)
        {
            try
            {
                DataTable dt = new DataTable();
                dt = table;
                StringBuilder sb = new StringBuilder();
                sb.Append("<table cellspacing="0" cellpadding="5" rules="all" border="1">");
                sb.Append("<tr style="font-weight: bold; white-space: nowrap;">");
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    sb.Append("<td>").Append(dt.Columns[i].ColumnName).Append("</td>");
                }
                sb.Append("</tr>");

                foreach (DataRow row in dt.Rows)
                {
                    sb.Append("<tr>");
                    for (int i = 0; i < dt.Columns.Count; i++)
                    {
                        sb.Append("<td>").Append(row[i].ToString()).Append("</td>");
                    }
                    sb.Append("</tr>");
                }
                sb.Append("</table>");
                toResponse(sb.ToString(), "application/vnd.ms - word", ".doc");
            }
            catch
            { }
        }
        /// <summary>
        /// 导出Excel
        /// </summary>
        /// <param name="table">参数类型：String 可以包含Html代码</param>
        public void toExcel(string strHtmlValue)
        {
            toResponse(strHtmlValue, "application/vnd.ms-excel", ".xls");
        }
        /// <summary>
        /// 导出Word
        /// </summary>
        /// <param name="table">参数类型：String 可以包含Html代码</param>
        public void toWord(string strHtmlValue)
        {
            toResponse(strHtmlValue, "application/vnd.ms-word", ".doc");
        }
        /// <summary>
        /// 导出Excel
        /// </summary>
        /// <param name="table">参数类型：System.Web.UI.Control 建议GridView</param>
        public void toExcel(System.Web.UI.Control source)
        {
            try
            {
                HttpResponse Response = HttpContext.Current.Response;
                Response.Clear();
                Response.Buffer = true;
                Response.Write("<meta http-equiv=Content-Type content=text/html;charset=gb2312>");
                Response.AppendHeader("Content-Disposition", "attachment;filename=" + strFileName + ".xls");
                Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
                Response.AddHeader("base", "target=_blank");
                Response.ContentType = "application/vnd.ms-excel";

                //关闭控件的视图状态
                source.Page.EnableViewState = false;

                //初始化HtmlWriter
                System.IO.StringWriter writer = new System.IO.StringWriter();
                System.Web.UI.HtmlTextWriter htmlWriter = new System.Web.UI.HtmlTextWriter(writer);
                //source.RenderControl(htmlWriter);

                //预防出现控件必须放在具有 runat=server 的窗体标记内的错误
                System.Web.UI.Page page = new System.Web.UI.Page();
                HtmlForm form = new HtmlForm();
                source.EnableViewState = false;
                page.EnableEventValidation = false;
                page.DesignerInitialize();
                page.Controls.Add(form);
                form.Controls.Add(source);
                page.RenderControl(htmlWriter);

                //输出
                Response.Write(writer.ToString());
                Response.End();
            }
            catch
            {
            }
        }
        /// <summary>
        /// 导出Word
        /// </summary>
        /// <param name="table">参数类型：System.Web.UI.Control 建议GridView</param>
        public void toWord(System.Web.UI.Control source)
        {
            try
            {
                HttpResponse Response = HttpContext.Current.Response;
                Response.Clear();
                Response.Buffer = true;
                Response.Write("<meta http-equiv=Content-Type content=text/html;charset=gb2312>");
                Response.AppendHeader("Content-Disposition", "attachment;filename=" + strFileName + ".doc");
                Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
                Response.AddHeader("base", "target=_blank");
                Response.ContentType = "application/vnd.ms-word";

                //关闭控件的视图状态
                source.Page.EnableViewState = false;

                //初始化HtmlWriter
                System.IO.StringWriter writer = new System.IO.StringWriter();
                System.Web.UI.HtmlTextWriter htmlWriter = new System.Web.UI.HtmlTextWriter(writer);
                //source.RenderControl(htmlWriter);

                //预防出现控件必须放在具有 runat=server 的窗体标记内的错误
                System.Web.UI.Page page = new System.Web.UI.Page();
                HtmlForm form = new HtmlForm();
                source.EnableViewState = false;
                page.EnableEventValidation = false;
                page.DesignerInitialize();
                page.Controls.Add(form);
                form.Controls.Add(source);
                page.RenderControl(htmlWriter);

                //输出
                Response.Write(writer.ToString());
                Response.End();
            }
            catch
            { }
        }
        /// <summary>
        /// 导出PDF
        /// </summary>
        /// <param name="strPath">参数类型：System 建议使用Server.MapPath("~")获取根目录</param>
        /// <param name="datatable">参数类型：DataTable</param>
        public void toPDF(string strPath, DataTable datatable)
        {
            try
            {
                string strFilesPath = strPath + "\TempPDF";
                if (!Directory.Exists(strFilesPath))
                {
                    Directory.CreateDirectory(strFilesPath);
                }
                strFilesPath = strFilesPath + "\" + strFileName + ".pdf";
                Document document = new Document();
                PdfWriter.GetInstance(document, new FileStream(strFilesPath, FileMode.Create));
                document.Open();
                BaseFont bfChinese = BaseFont.CreateFont("C://WINDOWS//Fonts//simsun.ttc,1", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
                Font fontChinese = new Font(bfChinese, 12, Font.NORMAL, new Color(0, 0, 0));

                //document.Add(new Paragraph(this.TextBox1.Text.ToString(), fontChinese));

                //iTextSharp.text.Image jpeg = iTextSharp.text.Image.GetInstance(Server.MapPath("pic015.jpg"));
                //document.Add(jpeg);
                PdfPTable table = new PdfPTable(datatable.Columns.Count);

                for (int i = 0; i < datatable.Rows.Count; i++)
                {
                    for (int j = 0; j < datatable.Columns.Count; j++)
                    {
                        table.AddCell(new Phrase(datatable.Rows[i][j].ToString(), fontChinese));
                    }
                }
                document.Add(table);

                document.Close();

                String FullFileName = strFilesPath;
                FileInfo DownloadFile = new FileInfo(FullFileName);
                System.Web.HttpContext.Current.Response.Clear();
                System.Web.HttpContext.Current.Response.ClearHeaders();
                System.Web.HttpContext.Current.Response.Buffer = false;
                System.Web.HttpContext.Current.Response.ContentType = "application/octet-stream";
                System.Web.HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + strFileName + ".pdf");
                System.Web.HttpContext.Current.Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
                System.Web.HttpContext.Current.Response.WriteFile(DownloadFile.FullName);
                System.Web.HttpContext.Current.Response.Flush();
                System.Web.HttpContext.Current.Response.End();
            }
            catch
            {
            }
        }
        protected void toResponse(string strResValue, string strContentType, string strGS)
        {
            HttpResponse Response = HttpContext.Current.Response;
            Response.Clear();
            Response.Buffer = true;
            Response.Write("<meta http-equiv=Content-Type content=text/html;charset=gb2312>");
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + strFileName + strGS);
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            Response.AddHeader("base", "target=_blank");
            Response.ContentType = strContentType;
            Response.Write(strResValue);
            Response.End();
        }
        /// <summary>
        /// 从Excel中导出数据到DataTable中
        /// </summary>
        /// <param name="TempFilePath">参数类型：Excel文件的位置</param>
        /// <param name="strSheetName">参数类型：Excel文件中包含数据的Sheet名称，默认为""=Sheet1</param>
        /// <returns name="DataTable">返回Excel中数据</returns>
        public DataTable intoDataTable(string TempFilePath, string strSheetName)
        {
            string strSheetNameValue = "Sheet1{1}quot;;
            if (strSheetName.Trim() != "")
            {
                strSheetNameValue = strSheetName + "{1}quot;;
            }
            string strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + TempFilePath + ";Extended Properties=Excel 8.0";
            //链接Excel
            OleDbConnection cnnxls = new OleDbConnection(strConn);
            //读取Excel里面有 表Sheet1
            OleDbDataAdapter oda = new OleDbDataAdapter("select * from [" + strSheetNameValue + "]", cnnxls);
            DataSet ds = new DataSet();
            //将Excel里面有表内容装载到内存表中！
            oda.Fill(ds);
            DataTable dt = ds.Tables[0];
            return dt;
        }
    }
}

其中using  iTextSharp;的引用dll 下载地址：http://sourceforge.net/projects/itextsharp/