C#interop:在将新工作表添加到现有文件后,excel进程不会退出

Question

可能重复:
如何在C#中正确清理Excel互操作对象

我在这里阅读了许多关于管理COM引用的其他线程,同时使用.Net-Excel互操作来确保Excel进程在退出时正确退出,到目前为止,这些技术已经运行良好,但我最近遇到了一个将新工作表添加到现有工作簿文件时出现问题.

下面的代码留下了僵尸Excel进程.

如果我将工作表添加到新创建的工作簿文件,它将退出正常.如果我运行除.Add()行之外的代码,它会退出.(我正在读取的现有文件是由注释掉的代码创建的空文件)

有任何想法吗？

//using Excel = Microsoft.Office.Interop.Excel;
//using System.Runtime.InteropServices;
public static void AddTest()
{
  string filename = @"C:\addtest.xls";
  object m = Type.Missing;
  Excel.Application excelapp = new Excel.Application();
  if (excelapp == null) throw new Exception("Can't start Excel");
  Excel.Workbooks wbs = excelapp.Workbooks;

  //if I create a new file and then add a worksheet,
  //it will exit normally (i.e. if you uncomment the next two lines
  //and comment out the .Open() line below):
  //Excel.Workbook wb = wbs.Add(Excel.XlWBATemplate.xlWBATWorksheet);
  //wb.SaveAs(filename, m, m, m, m, m, 
  //          Excel.XlSaveAsAccessMode.xlExclusive,
  //          m, m, m, m, m);

  //but if I open an existing file and add a worksheet,
  //it won't exit (leaves zombie excel processes)
  Excel.Workbook wb = wbs.Open(filename,
                               m, m, m, m, m, m,
                               Excel.XlPlatform.xlWindows,
                               m, m, m, m, m, m, m);

  Excel.Sheets sheets = wb.Worksheets;

  //This is the offending line:
  Excel.Worksheet wsnew = sheets.Add(m, m, m, m) as Excel.Worksheet; 

  //N.B. it doesn't help if I try specifying the parameters in Add() above

  wb.Save();
  wb.Close(m, m, m);

  //overkill to do GC so many times, but shows that doesn't fix it
  GC();
  //cleanup COM references
  //changing these all to FinalReleaseComObject doesn't help either
  while (Marshal.ReleaseComObject(wsnew) > 0) { } 
  wsnew = null;
  while (Marshal.ReleaseComObject(sheets) > 0) { }
  sheets = null;
  while (Marshal.ReleaseComObject(wb) > 0) { }
  wb = null;
  while (Marshal.ReleaseComObject(wbs) > 0) { }
  wbs = null;
  GC();
  excelapp.Quit();
  while (Marshal.ReleaseComObject(excelapp) > 0) { }
  excelapp = null;
  GC();
}

public static void GC()
{
  System.GC.Collect();
  System.GC.WaitForPendingFinalizers();
  System.GC.Collect();
  System.GC.WaitForPendingFinalizers();
}

Answer 1

我做了类似的事情.我创建一个Excel文件或打开一个现有的.我删除所有工作表并添加我自己的工作表.这是我用来确保关闭所有引用的代码:

            workbook.Close(true, null, null);
            excelApp.Quit();

            if (newSheet != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(newSheet);
            }
            if (rangeSelection != null)
            {
            System.Runtime.InteropServices.Marshal.ReleaseComObject(rangeSelection);
            }
            if (sheets != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(sheets);
            }
            if (workbook != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
            }
            if (excelApp != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(excelApp);
            }

            newSheet = null;
            rangeSelection = null;
            sheets = null;
            workbook = null;
            excelApp = null;

            GC.Collect();

我已经用很多不同的选项对它进行了测试,并没有让它失败.

Answer 2

我手头没有代码，但我确实遇到了类似的问题。如果我没记错的话，我最终检索了 Excel 实例的进程 ID，并杀死了它（在适当的等待时间之后，并且当其他方法失败时）。

我想我用过：

GetWindowThreadProcessId（通过P/Invoke）对excel对象的hwnd属性获取进程id，然后用于Process.GetProcessById获取进程对象。完成此操作后，我会调用Kill该流程。

编辑：我必须承认，这不是理想的解决方案，但如果您找不到未发布的流氓界面，那么这将以真正的蛋壳/大锤方式修复它。;)

EDIT2：您不必Kill立即调用流程对象...您可以先尝试调用Close，然后再诉诸Kill.