C# = 为什么 Excel 进程没有结束？

我有以下代码：

private bool IsMousetrapFile(string path)
    {

        logger.Log(validateFileMessage + path);

        Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
        Excel.Workbooks workbooks = xlApp.Workbooks;
        Excel.Workbook xlWorkBook = workbooks.Open(path, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
        Excel.Sheets worksheets = (Excel.Sheets)xlWorkBook.Worksheets;
        Excel.Worksheet ws = null;


        foreach (string sheet in expectedWorksheets)
        {

            try
            {

                ws = (Excel.Worksheet)worksheets.get_Item(sheet);
                logger.Log(validMousetrapFileMessage + path);
            }
            catch
            {
                logger.Log(validateSheetError + sheet + ": " + path);
                if (ws != null)
                    Marshal.ReleaseComObject(ws);
                Marshal.ReleaseComObject(worksheets);
                Marshal.ReleaseComObject(xlWorkBook);
                Marshal.ReleaseComObject(workbooks);
                Marshal.ReleaseComObject(xlApp);

                return false;

            }

        }

        if (ws != null)
            Marshal.ReleaseComObject(ws);
        Marshal.ReleaseComObject(worksheets);
        Marshal.ReleaseComObject(xlWorkBook);
        Marshal.ReleaseComObject(workbooks);
        Marshal.ReleaseComObject(xlApp);

        return true;


    }

实际上，它检查 Excel 工作簿是否包含特定工作表。不管有没有，我都希望Excel进程结束。但是，每次打开新工作簿时，都会添加一个新进程，并且永远不会删除？

附言。我知道那里有重复的代码......它很快就会被整理:)

Use Excel.Application.Quit()当您完成处理或正在做的任何事情时。

在你的情况下：xlApp.Quit();

UPDATE:

@Lasse V.卡尔森指出如果 Excel 已在运行则该怎么做。好吧，这是一个解决方案：（我没有测试代码，这只是为了给您一个想法）

private void TestMethod()
{
   bool excelWasRunning = System.Diagnostics.Process.GetProcessesByName("excel").Length > 0;

   // your code

   if (!excelWasRunning)
   { 
       xlApp.Quit();
   }
}