dataset 导出Excel

 /// <summary>   
        ///    
        /// </summary>   
        /// <param name="dataSet">要导出的数据来源</param>   
        /// <param name="fileName">导出的Excel名称</param>   
        /// <param name="saveDirectoryName">要保存到服务器上文件夹的名称</param>   
        /// <param name="deleteOldFile">指示是否删除旧文件</param>   
        /// [特别说明] 当指定DataTable某列加入链接时，需在数据源给DataTable增设两个扩展属性  如下格式：   
        ///    DataTableShowLinkSettingsModel dsm=new DataTableShowLinkSettingsModel();   
        ///    dsm.IsShowLink = true;//设置该表是否显示超链接   
        ///    dsm.ShowLinkColumns = new int[] { 2};//设置哪一列显示为超链接   
        ///    dt2.ExtendedProperties.Add("DataTableShowLinkSettings", dsm);//放入扩展属性   
        public static string DataSetToLocalExcel(DataSet dataSet, string fileName, string saveDirectoryName, bool deleteOldFile)
        {
            if (dataSet==null)
            {
                return "count:0";
            }
            //设置导出文件在服务器上的文件夹   
            //saveDirectoryName = string.Empty;
            deleteOldFile = true;
            string exportDir = string.Empty;
            string directoryPath = string.Empty;
            string rootPath = HttpContext.Current.Server.MapPath(HttpContext.Current.Request.ApplicationPath);
            if (string.IsNullOrEmpty(saveDirectoryName))
            {
                directoryPath = rootPath + "UploadFiles\\ExportExcelFile";
            }
            else
            {
                directoryPath = rootPath + saveDirectoryName;
            }
            if (!Directory.Exists(directoryPath))
            {
                Directory.CreateDirectory(directoryPath);
            }
            exportDir = directoryPath;
            //设置文件在服务器上的路径   
            string outputPath = exportDir + "\\" + fileName;
            string dowloadUrl = "/UploadFiles/ExportExcelFile/" + fileName;
            if (deleteOldFile)
            {
                if (System.IO.File.Exists(outputPath)) { System.IO.File.Delete(outputPath); }
            }
            object missing = System.Reflection.Missing.Value;
            Excel.Application app = new Excel.ApplicationClass();
            app.Application.Workbooks.Add(true);
            Excel.Workbook excelWorkbook =  (Excel.Workbook)app.ActiveWorkbook;//获取添加的workbook


            //创建Excel应用实例
            //Application excelApp = new Application();

            //创建Excel文档  
            //Workbook excelWorkbook = excelApp.Workbooks.Add(Type.Missing);

            //for (int i = 0; i < dataSet.Tables.Count; i++)
            //{
            //    //excelWorkbook.Sheets.Add();
            //    excelWorkbook.Worksheets.Add(Type.Missing,Type.Missing,1,Type.Missing);
            //}
            
            int sheetIndex = 0;


            foreach (System.Data.DataTable dt in dataSet.Tables)
            {

                try
                {
                     //每个table都要放到数组中以便于Excel绑定
                    object[,] rawData = new object[dt.Rows.Count + 1, dt.Columns.Count];


                    for (int col = 0; col < dt.Columns.Count; col++)
                    {
                        //把列明放到数组的第一行中 
                        rawData[0, col] = dt.Columns[col].ColumnName;

                        //将数据放到数组中中每一列都添加到数组
                        for (int row = 0; row < dt.Rows.Count; row++)
                        {
                            rawData[row + 1, col] = dt.Rows[row].ItemArray[col];
                        }
                    }


                    //创建列标   
                    string finalColLetter = string.Empty;
                    string colCharset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
                    int colCharsetLen = colCharset.Length;

                    if (dt.Columns.Count > colCharsetLen)
                    {
                        finalColLetter = colCharset.Substring(
                            (dt.Columns.Count - 1) / colCharsetLen - 1, 1);
                    }

                    finalColLetter += colCharset.Substring(
                            (dt.Columns.Count - 1) % colCharsetLen, 1);



                    ++sheetIndex;                   
                    //这种方式会自动创建一个sheet，因此先用了默认的，然后再添加
                    Microsoft.Office.Interop.Excel.Worksheet excelSheet = (Microsoft.Office.Interop.Excel.Worksheet)excelWorkbook.Worksheets[sheetIndex];
                    
                    //下一个页小于等于表格总数就加一个sheet
                    if (sheetIndex+1<=dataSet.Tables.Count)
                    {
                        excelWorkbook.Worksheets.Add(Type.Missing, Type.Missing, 1, Type.Missing);
                    }                    
                    

                    excelSheet.Name = dt.TableName;
                    //工作区中的范围设定 
                    string excelRange = string.Format("A1:{0}{1}",
                        finalColLetter, dt.Rows.Count + 1);

                    excelSheet.get_Range(excelRange, Type.Missing).Value2 = rawData;

                    // 第一行变成粗体  
                    ((Range)excelSheet.Rows[1, Type.Missing]).Font.Bold = true;

                    //调整列宽为自适应
                    Range allColumn = excelSheet.Columns; 
                    allColumn.AutoFit(); 
                }
                catch (Exception)
                {

                    throw;
                }

                #region 设置超链接
                //DataTableShowLinkSettingsModel dsm = dt.ExtendedProperties["DataTableShowLinkSettings"] == null ? null : (DataTableShowLinkSettingsModel)dt.ExtendedProperties["DataTableShowLinkSettings"];
                //if (dsm != null)
                //{
                //    bool flag = dsm.IsShowLink;
                //    int[] addHyperlinksColumnsList = dsm.ShowLinkColumns;
                //    if (flag)
                //    {
                //        if (addHyperlinksColumnsList != null && addHyperlinksColumnsList.Length > 0)
                //        {
                //            int rowsCount = excelSheet.UsedRange.Rows.Count;
                //            int columnCount = excelSheet.UsedRange.Columns.Count;
                //            for (int i = 1; i < rowsCount; i++)
                //            {
                //                for (int j = 0; j < addHyperlinksColumnsList.Length; j++)
                //                {
                //                    Range range = (Range)excelSheet.Cells[i + 1, addHyperlinksColumnsList[j]];
                //                    //要添加的单元格位置   
                //                    string link = range.Cells.Value2 == null ? "" : range.Cells.Value2.ToString();
                //                    excelSheet.Hyperlinks.Add(range, link, Type.Missing, Type.Missing, Type.Missing);
                //                }
                //            }
                //        }
                //    }
                //}
                #endregion
            }
             
            app.Application.DisplayAlerts = false;//过程中的提示不弹出
            //保存文档
            excelWorkbook.SaveAs(outputPath);
            
            excelWorkbook.Close(true, missing,missing);
            excelWorkbook = null;

            //释放应用 
            app.Quit();
            app = null;

            //回收对象
            GC.Collect();
            GC.WaitForPendingFinalizers();
            //DownExcelFromServer(outputPath, fileName);
            return dowloadUrl;
        }