导出excel代码，为何导出成功后，excel进程总是存在一个呢？
导出excel代码，为何导出成功后，excel进程总是存在一个呢？
比较怪，已经执行清理了，而且清理好象也起作用。

比如执行两次导出，第一次导出后，进程中留下一个 excel 进程，然后进行第二次导出，在导出过程中，任务管理器查看进程，会有 2 个 excel 进程，导出结束后，第二个excel进程会关闭（这说明我的清理代码起作用了）

但是为何进程中总会有一个excel进程无法销毁呢？
代码如下：

C# code

        public static void SaveAs(DataGridView gridView)        {            //导出到execl               try            {                SaveFileDialog saveFileDialog = new SaveFileDialog();                saveFileDialog.Filter = "导出Excel (*.xls)|*.xls";                saveFileDialog.FilterIndex = 0;                saveFileDialog.RestoreDirectory = true;                //saveFileDialog.CreatePrompt = true;                saveFileDialog.Title = "导出Excel格式文档";                saveFileDialog.ShowDialog();                string strName = saveFileDialog.FileName;                if (strName.Length != 0)                {                    //toolStripProgressBar1.Visible = true;                    //以下变量什么意思？                    System.Reflection.Missing miss = System.Reflection.Missing.Value;                    Microsoft.Office.Interop.Excel.ApplicationClass excel = new Microsoft.Office.Interop.Excel.ApplicationClass();                    excel.Application.Workbooks.Add(true);                    excel.Visible = false;//若是true，则在导出的时候会显示EXcel界面                    //excel.Visible = true;                    if (excel == null)                    {                        MessageBox.Show("EXCEL无法启动！(可能您没有安装EXCEL，或者版本与本程序不符)","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);                        return;                    }                    Microsoft.Office.Interop.Excel.Workbooks books = (Microsoft.Office.Interop.Excel.Workbooks)excel.Workbooks;                    Microsoft.Office.Interop.Excel.Workbook book = (Microsoft.Office.Interop.Excel.Workbook)(books.Add(miss));                    Microsoft.Office.Interop.Excel.Worksheet sheet = (Microsoft.Office.Interop.Excel.Worksheet)book.ActiveSheet;                    sheet.Name = "数据";                    //int m = 0, n = 0;                    //添加表头                    for (int i = 0; i < gridView.ColumnCount; i++)                    {                        excel.Cells[1, i+1] = gridView.Columns[i].HeaderText.ToString();                    }                    //填充数据                    for (int i = 0; i < gridView.RowCount; i++)                    {                        //i为行，j为列                        for (int j = 0; j < gridView.ColumnCount; j++)                        {                            ////注意：datagrid的引用方法是 datagrid1[列，行],即先列后行                            if (gridView[j, i].Value.GetType() == typeof(string))                            {                                //MessageBox.Show(gridView[j, i].Value.ToString());                                excel.Cells[i + 2, j + 1] = "'" + gridView[j, i].Value.ToString();                            }                            else                            {                                excel.Cells[i + 2, j + 1] = gridView[j, i].Value.ToString();                            }                        }                        //toolStripProgressBar1.Value += 100 / gridView.RowCount;                    }                    sheet.SaveAs(strName, miss, miss, miss, miss, miss, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, miss, miss, miss);                    //book.Close(false, miss, miss);                    //books.Close();                    //excel.Quit();                    //System.Runtime.InteropServices.Marshal.ReleaseComObject(sheet);                    //System.Runtime.InteropServices.Marshal.ReleaseComObject(book);                    //System.Runtime.InteropServices.Marshal.ReleaseComObject(books);                    //System.Runtime.InteropServices.Marshal.ReleaseComObject(excel);                    //下面销毁excel进程，为何无效呢？                    NAR(sheet);                    book.Close(false,miss,miss);                    NAR(book);                    NAR(books);                    excel.Quit();                    NAR(excel);                    GC.Collect();                    MessageBox.Show("数据已经成功导出!");                    //toolStripProgressBar1.Value = 0;                    //System.Diagnostics.Process.Start(strName);                }            }            catch (Exception ex)            {                MessageBox.Show(ex.Message);            }        }        //消毁excel进程        private static void NAR(object o)        {            try             {                System.Runtime.InteropServices.Marshal.ReleaseComObject(o);            }            catch {}            finally             {                o = null;            }        } 
 

C# code

        TimeSpan beforeTime;            //Excel启动之前时间        TimeSpan afterTime;             //Excel启动之后时间        //记录进程创建时间        beforeTime = DateTime.Now.TimeOfDay;          Excel.ApplicationClass excel = new Excel.ApplicationClass();        afterTime = DateTime.Now.TimeOfDay;        /// <summary>        /// 杀 EXCEL 进程        /// </summary>        public void KillExcelProcess()        {            try            {                Process[] myProcesses;                TimeSpan startTime;                myProcesses = Process.GetProcessesByName("Excel");                //得不到Excel进程ID，暂时只能判断进程启动时?                foreach (Process myProcess in myProcesses)                {                    startTime = myProcess.StartTime.TimeOfDay;                    if (startTime > beforeTime && startTime < afterTime)                    {                        myProcess.Kill();                    }                }            }            catch (Exception ee)            {                //写入错误日志            }        }