读写Excel

　　　　 public string ShiPin()
        {
            //获取项目下的目录
            string filePath = AppDomain.CurrentDomain.BaseDirectory.Replace("\\", "/") + "视频.xls";

            //根据路径读取Excel，装进DataTable里
            System.Data.DataTable table = GetTableFromExcel("sheet1", filePath);

            //克隆 System.Data.DataTable 的结构，包括所有 System.Data.DataTable 架构和约束。（为了抓异常数据）
            System.Data.DataTable table200 = table.Clone();

            //清除数据
            table200.Clear();

            //视频路径
            string fileFullName = string.Empty;

            //根据条件查询Excel里列名为用户ID = user_id的第一条数据
            //DataRow dr = table.Select(string.Format("用户ID = ‘{0}‘", user_id)).First();

            if (table != null && table.Rows.Count > 0)
            {
                for (int i = 0; i < table.Rows.Count; ++i)
                {
                    //获取第i+1行的Excel数据
                    DataRow dateRow = table.Rows[i];
                    //获取视频路径，例：www.baidu.com/Files/1.f4v 或wmv格式
                    string path = dateRow["RESOURSE_URL"].ToString();
                    if (!string.IsNullOrEmpty(path))
                    {
                        //获取本地视频路径
                        fileFullName = path.Replace("www.baidu.com/Files", "F:/视频").Replace(".f4v", ".mp4").Replace(".wmv", ".mp4");
                        //判断视频是否存在
                        if (System.IO.File.Exists(fileFullName))
                        {
                            //读取视频
                            FileStream fs = new FileStream(fileFullName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
                            //判断视频大于200M
                            if (fs.Length > 209715200)
                            {
                                string destPath = Path.Combine(@"E:\视频", Path.GetFileName(fileFullName));
　　　　　　　　　　　　　　　　　　 //复制原有视频，到新的目录下
                                System.IO.File.Copy(fileFullName, destPath, true);
                                table200.ImportRow(dateRow);
                            }
                            else
                            {
                                byte[] str2 = new byte[fs.Length];
                                fs.Read(str2, 0, str2.Length);
                                fs.Close();
                                fs.Dispose();
                                //上传视频（未写）
                            }
                        }
                    }
                    //回收
                    GC.Collect();
                }
            }
            //如果有异常数据，则将异常数据输出到dayu200文件夹的1.xls里
            if (table200 != null && table200.Rows.Count > 0)
            {
                DataTabletoExcel(table200, AppDomain.CurrentDomain.BaseDirectory.Replace("\\", "/") + "dayu200/1.xls");
            }
            return "";
        }

        /// <summary>
        /// 获取Excel内容。
        /// </summary>
        /// <param name="sheetName">工作表名称，例：sheet1</param>
        /// <param name="filePath">Excel路径</param>
        /// <returns></returns>
        private DataTable GetTableFromExcel(string sheetName, string filePath)
        {
            const string connStrTemplate = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=Excel 8.0;";
            DataTable dt = null;
            if (!System.IO.File.Exists(filePath))
            {
                // don‘t find file
                return null;
            }
            OleDbConnection conn = new OleDbConnection(string.Format(connStrTemplate, filePath));
            try
            {
                conn.Open();
                if (sheetName == null || sheetName.Trim().Length == 0)
                {
                    DataTable schemaTable = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                    sheetName = schemaTable.Rows[0]["TABLE_NAME"].ToString().Trim();
                }
                else
                {
                    sheetName += "$";
                }

                string strSQL = "Select * From [" + sheetName + "]";
                OleDbDataAdapter da = new OleDbDataAdapter(strSQL, conn);
                DataSet ds = new DataSet();
                da.Fill(ds);
                dt = ds.Tables[0];
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                conn.Close();
            }

            return dt;
        }

        /// <summary>
        /// 将DataTable的数据写进Excel里
        /// </summary>
        /// <param name="tmpDataTable">DataTable数据</param>
        /// <param name="strFileName">Excel路径</param>
        public static void DataTabletoExcel(System.Data.DataTable tmpDataTable, string strFileName)
        {
            if (tmpDataTable == null)
            {
                return;
            }
            int rowNum = tmpDataTable.Rows.Count;
            int columnNum = tmpDataTable.Columns.Count;
            int rowIndex = 1;
            int columnIndex = 0;

            //需要引用Microsoft.Office.Interop.Excel.dll
            Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.ApplicationClass();
            xlApp.DefaultFilePath = "";
            xlApp.DisplayAlerts = true;
            xlApp.SheetsInNewWorkbook = 1;
            Microsoft.Office.Interop.Excel.Workbook xlBook = xlApp.Workbooks.Add(true);

            //将DataTable的列名导入Excel表第一行
            foreach (DataColumn dc in tmpDataTable.Columns)
            {
                columnIndex++;
                xlApp.Cells[rowIndex, columnIndex] = dc.ColumnName;
            }

            //将DataTable中的数据导入Excel中
            for (int i = 0; i < rowNum; i++)
            {
                rowIndex++;
                columnIndex = 0;
                for (int j = 0; j < columnNum; j++)
                {
                    columnIndex++;
                    xlApp.Cells[rowIndex, columnIndex] = tmpDataTable.Rows[i][j].ToString();
                }
            }

            //xlBook.SaveCopyAs(HttpUtility.UrlDecode(strFileName, System.Text.Encoding.UTF8));
            xlBook.SaveCopyAs(strFileName);
        }