//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[];

             //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[, 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[Column(列)][Row(行)] = 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;

         }