public string CreateExcel(string SelectedBizType, string strReportDate, DropDownList ddlYQ, DropDownList ddlDataTable, ref string strFilePath)
        {
            Application m_objExcel = new Application();
            int pid;
            GetWindowThreadProcessId(new IntPtr(m_objExcel.Hwnd), out pid);
            Workbooks m_objBooks = (Workbooks)m_objExcel.Workbooks;
            string strTepPath = string.Empty;
            string strTemplate = string.Empty;
            if (SelectedBizType == "3a448698-b695-4a5a-b405-df18f44da86f")
            {
                strTepPath = ConfigurationManager.AppSettings["TRQBBTemplate"];
                strTemplate = "天然气报表.xls";
            }
            else if (SelectedBizType == "969c388f-b0e2-4571-9876-4312b6a74a54")
            {
                strTepPath = ConfigurationManager.AppSettings["YCBBTemplate"];
                strTemplate = "油藏报表.xls";
            }
            try
            {
                string strFileDir = strTepPath + strReportDate + @"/";//将导出的excel保存到该路径下
                if (System.IO.Directory.Exists(strFileDir))//用来解决产能下载不稳定的问题
                {
                    System.IO.Directory.Delete(strFileDir, true);//如果由于上一次导出未成功，而留下了痕迹，先删除此文件夹，再创建
                }
                System.IO.Directory.CreateDirectory(strFileDir);//创建导出文件夹
                IDataBase oDB = DBFactory.GetDBInstance();

                string strYQName = string.Empty;
                string strTemplateChild = string.Empty;
                //遍历油区
                for (int i = 0; i < ddlYQ.Items.Count; i++)
                {
                    strYQName = ddlYQ.Items[i].Text;
                    //遍历表
                    for (int j = 0; j < ddlDataTable.Items.Count; j++)
                    {
                        string strShortCode = string.Empty;
                        string strDtName = ddlDataTable.Items[j].Text;
                      strTemplateChild = "XXXXX.xls";
                     strShortCode = "XXXXXXXXXXXX";
                                             //查询业务表数据
                        string strSql = string.Format("select * from " + strShortCode + " where ny=‘{0}‘ and yq=‘{1}‘", strReportDate.Substring(0, 6), strYQName);
                        System.Data.DataTable dtLast = oDB.GetDataTable(strSql);
                        if (dtLast.Rows.Count == 0)
                        {
                            continue;
                        }
                        _Workbook m_objBook = (_Workbook)m_objBooks.Add(strTepPath + strTemplateChild);
                        Sheets m_objSheets = (Sheets)m_objBook.Worksheets;
                        _Worksheet m_objSheet = (_Worksheet)(m_objSheets.get_Item(1));
                        //查询表结构字段
                        //                        string strSchama = string.Format(@"select column_name EnKey from user_tab_columns
                        //                                                                                            where upper(table_name)=upper(‘{0}‘)
                        //                                                                                            order by COLUMN_ID", strShortCode);
                        //                        System.Data.DataTable dtCols = oDB.GetDataTable(strSchama);
                        //                        string colNames = string.Empty;
                        //                        for (int k = 0; k < dtCols.Rows.Count; k++)
                        //                        {
                        //                            colNames += dtCols.Rows[k][0].ToString() + ",";
                        //                        }
                        //                        if (colNames.Length > 0)
                        //                        {
                        //                            colNames = colNames.Substring(0, colNames.Length - 1);
                        //                        }
                        //                        DownloadMutiRefineTable ddR = new DownloadMutiRefineTable();
                        //                        System.Data.DataTable dtResource = ddR.GetTableSchema(dtLast, colNames);
                        System.Data.DataTable dtResource = dtLast.Copy();
                        //将dataTable中的数据写入sheet
                        int headRows = m_objSheet.UsedRange.Rows.Count;
                        for (int k = 0; k < dtResource.Rows.Count; k++)
                        {
                            for (int m = 0; m < dtResource.Columns.Count; m++)
                            {
                                if (dtResource.Columns[m].ColumnName.ToUpper() == "STATUS")
                                {
                                    continue;
                                }
                                m_objSheet.Cells[k + headRows + 1, m + 1] = dtResource.Rows[k][m].ToString();
                            }
                        }
                        Range rCells = m_objSheet.Range[m_objSheet.Cells[headRows, 1],
                            m_objSheet.Cells[m_objSheet.UsedRange.Rows.Count, m_objSheet.UsedRange.Columns.Count]];  //shiying20140326 用来解决产能下载不稳定的问题
                        rCells.Borders.LineStyle = XlLineStyle.xlContinuous;
                        string save_path = strFileDir + ddlYQ.Items[i].Text + "_" + strReportDate + "_" + strTemplateChild;
                        m_objBook.SaveAs(save_path, XlFileFormat.xlXMLSpreadsheet, null, null, false, false,
                            XlSaveAsAccessMode.xlNoChange, null, null, null, null, null);
                        m_objBook.Close(false, null, null);
                    }
                }
                m_objBooks.Close();
                m_objExcel.Application.Quit();
                m_objExcel.Quit();

                //将得到的excel打包
                Crc32 crc = new Crc32();
                strFilePath = strTepPath + strReportDate + strTemplate.Replace(".xls", ".zip");
                ZipOutputStream zos = new ZipOutputStream(File.Create(strFilePath));
                //zos.SetLevel(6);
                DirectoryInfo di = new DirectoryInfo(strFileDir);
                foreach (FileInfo item in di.GetFiles())
                {
                    FileStream fs = File.OpenRead(item.FullName);
                    byte[] buffer = new byte[fs.Length];
                    fs.Read(buffer, 0, buffer.Length);
                    ZipEntry entry = new ZipEntry(strReportDate + strTemplate.Substring(0, strTemplate.Length - 4) + @"/" + item.Name);
                    entry.Size = fs.Length;
                    fs.Close();
                    crc.Reset();
                    crc.Update(buffer);
                    entry.Crc = crc.Value;
                    zos.PutNextEntry(entry);
                    zos.Write(buffer, 0, buffer.Length);
                }
                zos.Finish();
                zos.Close();
                System.IO.Directory.Delete(strFileDir, true);//删除导出文件夹             
            }
            catch (Exception err)
            {
                Message = err.Message;
            }
            return Message;
        }

excel 下载