是否需要使用Marshal.ReleaseComObject释放*每个*Excel互操作对象?

编辑

How do I properly clean up Excel interop objects? . 我最近遇到了这个问题,它为如何正确处理COM对象提供了很多见解。一定要在第一个(标记的)答案之外进行检查,因为其他答案超出了简单的“不要使用两点”和“使用两点” ReleaseComObject 对于每个com对象”的建议。

我重新讨论了这个问题,因为我意识到,尽管我对注册和处理所有COM对象都非常仔细,但我的Excel实例仍然没有得到正确的处理。事实证明,有一些方法可以创建完全不明显的COM对象(即,即使从不使用两点,也可能丢失COM对象)。另外,即使你很彻底,如果你的项目超过了一定的规模,丢失一个COM对象的几率也接近100%。当这种情况发生时,很难找到你错过的那个。上面链接的问题的答案提供了一些其他技术来确保Excel实例被关闭。同时,我对我的网站做了一个小的(但意义重大的)更新 ComObjectManager (以下)来反映我从上述问题中学到的东西。

我见过几个例子 Marshal.ReleaseComObject()

我想知道我是否能逃脱这样的惩罚:

var application = new ApplicationClass();
try
{
    // do work with application, workbooks, worksheets, cells, etc.
}
finally
{
    Marashal.ReleaseComObject(application)
}

或者如果我需要释放所创建的每个对象,如以下方法:

public void CreateExcelWorkbookWithSingleSheet()
{
    var application = new ApplicationClass();
    var workbook = application.Workbooks.Add(_missing);
    var worksheets = workbook.Worksheets;
    for (var worksheetIndex = 1; worksheetIndex < worksheets.Count; worksheetIndex++)
    {
        var worksheet = (WorksheetClass)worksheets[worksheetIndex];
        worksheet.Delete();
        Marshal.ReleaseComObject(worksheet);
    }
    workbook.SaveAs(
        WorkbookPath, _missing, _missing, _missing, _missing, _missing,
        XlSaveAsAccessMode.xlExclusive, _missing, _missing, _missing, _missing, _missing);
    workbook.Close(true, _missing, _missing);
    application.Quit();
    Marshal.ReleaseComObject(worksheets);
    Marshal.ReleaseComObject(workbook);
    Marshal.ReleaseComObject(application);
}

促使我问这个问题的原因是,作为林客的奉献者,我真的很想做这样的事情:

var worksheetNames = worksheets.Cast<Worksheet>().Select(ws => ws.Name);

…但我担心如果我不发布每个工作表,最终会导致内存泄漏或重影进程( ws

对此有任何见解都将不胜感激。

更新

根据目前的答案,听起来我真的需要释放我创建的每个com对象。我利用这个机会建立了一个 上课,让你更容易对付这种头痛。你必须记住使用 Get() 方法每次实例化一个新的com对象时,但如果这样做,它将为您处理其他所有事情。请让我知道,如果你看到任何问题与它(或编辑,并留下评论,如果你能)。代码如下:

public class ComObjectManager : IDisposable
{
    private Stack<object> _comObjects = new Stack<object>();

    public TComObject Get<TComObject>(Func<TComObject> getter)
    {
        var comObject = getter();
        _comObjects.Push(comObject);
        return comObject;
    }

    public void Dispose()
    {
        // these two lines of code will dispose of any unreferenced COM objects
        GC.Collect();
        GC.WaitForPendingFinalizers();

        while (_comObjects.Count > 0)
            Marshal.ReleaseComObject(_comObjects.Pop());
    }
}

下面是一个用法示例:

public void CreateExcelWorkbookWithSingleSheet()
{
    using (var com = new ComObjectManager())
    {
        var application = com.Get<ApplicationClass>(() => new ApplicationClass());
        var workbook = com.Get<Workbook>(() => application.Workbooks.Add(_missing));
        var worksheets = com.Get<Sheets>(() => workbook.Worksheets);
        for (var worksheetIndex = 1; worksheetIndex < worksheets.Count; worksheetIndex++)
        {
            var worksheet = com.Get<WorksheetClass>(() => (WorksheetClass)worksheets[worksheetIndex]);
            worksheet.Delete();
        }
        workbook.SaveAs(
            WorkbookPath, _missing, _missing, _missing, _missing, _missing,
            XlSaveAsAccessMode.xlExclusive, _missing, _missing, _missing, _missing, _missing);
        workbook.Close(true, _missing, _missing);
        application.Quit();
    }
}