//取数据dt   

                      string path = Server.MapPath("~\\tempzt\\");

                      if (dt.Rows.Count > 0)

                    {

                        System.Text.StringBuilder sb = new System.Text.StringBuilder();

                        string wjmc =  "xxxxxxxxxxxx".txt";

                        for (int n = 0; n < dt.Rows.Count; n++)

                        {

                            for (int m = 0; m < dt.Columns.Count; m++)

                            {

                                sb.Append(dt.Rows[n][m].ToString());

                                sb.Append("\t");

                            }

                            sb.Append("\r\n");

                        }

                        txt_export(sb, wjmc, path);

                    }

                }

            }

            //zip下载

            string[] files = Directory.GetFiles(path);

            if (files.Length > 0)

            {

                string name = "xxxxxxxxxxxx.zip";

                ZipFileMain(files, path + name, 9);

                DownLoadZip(path + name, name);

            }

            else

            {

                Response.Write("<script>alert('没有目标文件！请先写入')</script>");

            }

public void txt_export(StringBuilder sb, string wjmc, string path)

        {

            //zip下载

            string txtPath = path + wjmc;

            if (!Directory.Exists(path))

            {

                Directory.CreateDirectory(path);

            }

            if (File.Exists(txtPath))

            {

                File.Delete(txtPath);

            }

            StreamWriter sw = new StreamWriter(txtPath, false, System.Text.Encoding.Default);

            sw.Write(sb.ToString());

            sw.Close();

            //zip下载

        }

        //zip下载

        /// <summary>

        /// 压缩文件

        /// </summary>

        /// <param name="fileName">要压缩的所有文件（完全路径)</param>

        /// <param name="name">压缩后文件路径</param>

        /// <param name="Level">压缩级别</param>

        public void ZipFileMain(string[] filenames, string name, int Level)

        {

            if (File.Exists(name))

            {

                File.Delete(name);

            }

            ZipOutputStream s = new ZipOutputStream(File.Create(name));

            Crc32 crc = new Crc32();

            //压缩级别

            s.SetLevel(Level); // 0 - store only to 9 - means best compression

            try

            {

                foreach (string file in filenames)

                {

                    if (!Path.GetExtension(file).Equals(".txt"))

                    {

                        continue;

                    }

                    //打开压缩文件

                    FileStream fs = File.OpenRead(file);//文件地址

                    byte[] buffer = new byte[fs.Length];

                    fs.Read(buffer, 0, buffer.Length);

                    //建立压缩实体

                    ZipEntry entry = new ZipEntry(Path.GetFileName(file));//原文件名

                                                                          //时间

                    entry.DateTime = DateTime.Now;

                    //空间大小

                    entry.Size = fs.Length;

                    fs.Close();

                    crc.Reset();

                    crc.Update(buffer);

                    entry.Crc = crc.Value;

                    s.PutNextEntry(entry);

                    s.Write(buffer, 0, buffer.Length);

                    File.Delete(file);

                }

            }

            catch

            {

                throw;

            }

            finally

            {

                s.Finish();

                s.Close();

            }

        }

        public void DownLoadZip(string fileName,string name)

        {

            Response.ContentType = "application/x-zip-compressed";

            Response.AddHeader("Content-Disposition", "attachment;filename=" + name + "");

            Response.TransmitFile(fileName);

        }