我是否需要在每个'foreach'迭代中释放COM对象？

Question

这是(潜在的)问题:

我创建一个COM对象,然后使用'foreach'迭代它返回的集合中的每个元素.我是否需要释放我在集合中迭代的每个元素？(参见下面的代码.)如果是这样的话,我无法想出一种有效地从'finally'语句中释放它的方法,以防万一在项目被操作时出现错误.

有什么建议？

private static void doStuff()
{
    ComObjectClass manager = null;

    try
    {
        manager = new ComObjectClass();
        foreach (ComObject item in manager.GetCollectionOfItems())
        {
            Log.Debug(item.Name);
            releaseComObject(item); // <-- Do I need this line?
                                    //     It isn't in a 'finally' block...
                                    //             ...Possible memory leak?
        }
    }
    catch (Exception) { }
    finally
    {
        releaseComObject(manager);
    }
}

private static void releaseComObject(object instance)
{
    if (instance != null)
    {
        try
        {
            System.Runtime.InteropServices.Marshal.ReleaseComObject(instance);
        }
        catch
        {
            /* log potential memory leak */
            Log.Debug("Potential memory leak: Unable to release COM object.");
        }
        finally
        {
            instance = null;
        }
    }
}

Answer 1

您不应该使用foreach带有COM对象的语句,因为在您无法控制释放的场景后面进行引用.我会切换到一个for循环,并确保你永远不会使用COM对象的两个点.

这样看的方式是:

try
{
    manager = new ComObjectClass();
    ComObject comObject = null;
    ComObject[] collectionOfComItems = manager.GetCollectionOfItems();
    try
    {
        for(int i = 0; i < collectionOfComItems.Count; i++)
        {
            comObject = collectionOfComItems[i];
            ReleaseComObject(comObject);
        }
    }            
    finally
    {
        ReleaseComObject(comObject);
    }
}
finally 
{
    ReleaseComObject(manager);
}