c# 读取和写入excel数据

private void button1_Click(object sender, EventArgs e)
        {
            DataTable dt = GetDataFromExcelByConn();
            dataGridView1.DataSource = dt.DefaultView;
        }

        DataTable GetDataFromExcelByConn(bool hasTitle = false)
        {
            OpenFileDialog openFile = new OpenFileDialog();
            openFile.Filter = "Excel(*.xlsx)|*.xlsx|Excel(*.xls)|*.xls";
            openFile.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
            openFile.Multiselect = false;
            if (openFile.ShowDialog() == DialogResult.Cancel) return null;
            var filePath = openFile.FileName;
            string fileType = System.IO.Path.GetExtension(filePath);
            if (string.IsNullOrEmpty(fileType)) return null;

            using (DataSet ds = new DataSet())
            {
                // Microsoft.Jet.OLEDB.{0}.0.12.0
                string strCon = string.Format("Provider=Microsoft.ACE.OLEDB.{0}.0;" +
                                "Extended Properties=\"Excel {1}.0;HDR={2};IMEX=1;\";" +
                                "data source={3};",
                                (fileType == ".xls" ? 4 : 12), (fileType == ".xls" ? 8 : 12), (hasTitle ? "Yes" : "NO"), filePath);
                string strCom = " SELECT * FROM [Sheet1$]";
                using (OleDbConnection myConn = new OleDbConnection(strCon))
                using (OleDbDataAdapter myCommand = new OleDbDataAdapter(strCom, myConn))
                {
                    myConn.Open();
                    myCommand.Fill(ds);
                }
                if (ds == null || ds.Tables.Count <= 0) return null;
                return ds.Tables[0];
            }
        }

       //将数据写入已存在Excel
        public static void writeExcel(string result, string filepath)
        {
            //1.创建Applicaton对象
            Microsoft.Office.Interop.Excel.Application xApp = new

            Microsoft.Office.Interop.Excel.Application();

            //2.得到workbook对象，打开已有的文件
            Microsoft.Office.Interop.Excel.Workbook xBook = xApp.Workbooks.Open(filepath,
                                  Missing.Value, Missing.Value, Missing.Value, Missing.Value,
                                  Missing.Value, Missing.Value, Missing.Value, Missing.Value,
                                  Missing.Value, Missing.Value, Missing.Value, Missing.Value);

            //3.指定要操作的Sheet
            Microsoft.Office.Interop.Excel.Worksheet xSheet = (Microsoft.Office.Interop.Excel.Worksheet)xBook.Sheets[1];

            //在第一列的左边插入一列  1:第一列
            //xlShiftToRight:向右移动单元格   xlShiftDown:向下移动单元格
            //Range Columns = (Range)xSheet.Columns[1, System.Type.Missing];
            //Columns.Insert(XlInsertShiftDirection.xlShiftToRight, Type.Missing);

            //4.向相应对位置写入相应的数据
            xSheet.Cells[1][2] = result;

            //5.保存保存WorkBook
            xBook.Save();
            //6.从内存中关闭Excel对象

            xSheet = null;
            xBook.Close();
            xBook = null;
            //关闭EXCEL的提示框
            xApp.DisplayAlerts = false;
            //Excel从内存中退出
            xApp.Quit();
            xApp = null;
        }

        /// <summary>
        /// 关闭Excel进程
        /// </summary>
        /// <param name="excelPath"></param>
        /// <param name="excel"></param>
        /// <param name="wb"></param>
        public void ClosePro(string excelPath, Excel.Application excel, Excel.Workbook wb)
        {
            Process[] localByNameApp = Process.GetProcessesByName(excelPath);//获取程序名的所有进程
            if (localByNameApp.Length > 0)
            {
                foreach (var app in localByNameApp)
                {
                    if (!app.HasExited)
                    {
                        #region
                        ////设置禁止弹出保存和覆盖的询问提示框   
                        //excel.DisplayAlerts = false;
                        //excel.AlertBeforeOverwriting = false;

                        ////保存工作簿   
                        //excel.Application.Workbooks.Add(true).Save();
                        ////保存excel文件   
                        //excel.Save("D:" + "\\test.xls");
                        ////确保Excel进程关闭   
                        //excel.Quit();
                        //excel = null; 
                        #endregion
                        app.Kill();//关闭进程  
                    }
                }
            }
            if (wb != null)
                wb.Close(true, Type.Missing, Type.Missing);
            excel.Quit();
            // 安全回收进程
            System.GC.GetGeneration(excel);
        }