问题描述
我如何可以调用私人COM接口的方法，在基类中定义，从派生类？
How can I invoke a method of a private COM interface, defined in a base class, from a derived class?
例如，这里是COM接口， IComInterface （IDL）：
For example, here is the COM interface, IComInterface (IDL):
[
uuid(9AD16CCE-7588-486C-BC56-F3161FF92EF2),
oleautomation
]
interface IComInterface: IUnknown
{
HRESULT ComMethod([in] IUnknown* arg);
}
下面是C＃类的BaseClass 从 OldLibrary 组件，它实现 IComInterface 这样的（注意接口被声明为private）：
Here's the C# class BaseClass from OldLibrary assembly, which implements IComInterface like this (note the interface is declared as private):
// Assembly "OldLibrary"
public static class OldLibrary
{
[ComImport(), Guid("9AD16CCE-7588-486C-BC56-F3161FF92EF2")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IComInterface
{
void ComMethod([In, MarshalAs(UnmanagedType.Interface)] object arg);
}
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class BaseClass : IComInterface
{
void IComInterface.ComMethod(object arg)
{
Console.WriteLine("BaseClass.IComInterface.ComMethod");
}
}
}
最后，这里是一个改进版本， ImprovedClass ，这源于的BaseClass ，但声明并实现它自己版本对 IComInterface ，因为基本的 OldLibrary.IComInterface 不可访问：
Finally, here's an improved version, ImprovedClass, which derives from BaseClass, but declares and implement its own version of IComInterface, because the base's OldLibrary.IComInterface is inaccessible:
// Assembly "NewLibrary"
public static class NewLibrary
{
[ComImport(), Guid("9AD16CCE-7588-486C-BC56-F3161FF92EF2")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IComInterface
{
void ComMethod([In, MarshalAs(UnmanagedType.Interface)] object arg);
}
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class ImprovedClass :
OldLibrary.BaseClass,
IComInterface,
ICustomQueryInterface
{
// IComInterface
void IComInterface.ComMethod(object arg)
{
Console.WriteLine("ImprovedClass.IComInterface.ComMethod");
// How do I call base.ComMethod here,
// otherwise than via reflection?
}
// ICustomQueryInterface
public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv)
{
if (iid == typeof(IComInterface).GUID)
{
ppv = Marshal.GetComInterfaceForObject(this, typeof(IComInterface), CustomQueryInterfaceMode.Ignore);
return CustomQueryInterfaceResult.Handled;
}
ppv = IntPtr.Zero;
return CustomQueryInterfaceResult.NotHandled;
}
}
}
我怎么叫 BaseClass.ComMethod 从 ImprovedClass.ComMethod 没有反映？
我可以使用反射，但在实际使用的情况下 IComInterface 是一些复杂的签名成员的复杂的OLE接口。
How do I call BaseClass.ComMethod from ImprovedClass.ComMethod without reflection?
I could use reflection, but in the real use case IComInterface is a complex OLE interface with a number of members of complex signatures.
我想，因为这两个 BaseClass.IComInterface 和 ImprovedClass.IComInterface 都具有相同GUID的两个COM接口和相同的方法签名，并有 COM类型等效在.NET 4.0+，所以必须有一种方法做什么，我以后是没有反映。
I thought that because both BaseClass.IComInterface and ImprovedClass.IComInterface are both COM interfaces with the same GUID and identical method signatures, and there's COM Type Equivalence in .NET 4.0+, so there has to be a way to do what I'm after without reflection.
另一个要求是， ImprovedClass 已经从的BaseClass 导出，因为C＃的客户端code预计， 的BaseClass ，它传递给COM客户端code的一个实例。因此，的BaseClass 壳内 ImprovedClass 不是一个选项。
Another requirement is that ImprovedClass has to be derived from BaseClass, because the C# client code expects an instance of BaseClass, which it passes to the COM client code. Thus, containment of BaseClass inside ImprovedClass is not an option.
一个真实的场景这涉及到从的和 WebBrowserSite 这里描述 。
A real-life scenario which involves deriving from WebBrowser and WebBrowserSite is described here.
推荐答案
我想通了，通过使用一个包含辅助对象（ BaseClassComProxy ）和聚合COM代理对象与 Marshal.CreateAggregatedObject 。这种做法使我有独立的身份非托管的对象，我可以投（有 Marshal.GetTypedObjectForIUnknown ），以 BaseClass.IComInterface 接口，这是不以其他方式可访问的。它适用于任何其他私人COM接口，通过的BaseClass 实施。
I figured it out, by using a helper contained object (BaseClassComProxy) and an aggregated COM proxy object, created with Marshal.CreateAggregatedObject. This approach gives me an unmanaged object with separate identity, which I can cast (with Marshal.GetTypedObjectForIUnknown) to my own equivalent version of BaseClass.IComInterface interface, which is not otherwise accessible. It works for any other private COM interfaces, implemented by BaseClass.
@ EricBrown的有关COM身份规则点已经帮助了很多与此研究。感谢埃里克！
@EricBrown's points about COM identity rules have helped a lot with this research. Thanks Eric!
下面是一个独立的控制台测试应用程序。在code解决与 WebBrowserSite 张贴这里。
using System;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
namespace ManagedServer
{
/*
// IComInterface IDL definition
[
uuid(9AD16CCE-7588-486C-BC56-F3161FF92EF2),
oleautomation
]
interface IComInterface: IUnknown
{
HRESULT ComMethod(IUnknown* arg);
}
*/
// OldLibrary
public static class OldLibrary
{
// private COM interface IComInterface
[ComImport(), Guid("9AD16CCE-7588-486C-BC56-F3161FF92EF2")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IComInterface
{
void ComMethod([In, MarshalAs(UnmanagedType.Interface)] object arg);
}
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class BaseClass : IComInterface
{
void IComInterface.ComMethod(object arg)
{
Console.WriteLine("BaseClass.IComInterface.ComMethod");
}
}
}
// NewLibrary
public static class NewLibrary
{
// OldLibrary.IComInterface is inaccessible here,
// define a new equivalent version
[ComImport(), Guid("9AD16CCE-7588-486C-BC56-F3161FF92EF2")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IComInterface
{
void ComMethod([In, MarshalAs(UnmanagedType.Interface)] object arg);
}
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class ImprovedClass :
OldLibrary.BaseClass,
NewLibrary.IComInterface,
ICustomQueryInterface,
IDisposable
{
NewLibrary.IComInterface _baseIComInterface;
BaseClassComProxy _baseClassComProxy;
// IComInterface
// we want to call BaseClass.IComInterface.ComMethod which is only accessible via COM
void IComInterface.ComMethod(object arg)
{
_baseIComInterface.ComMethod(arg);
Console.WriteLine("ImprovedClass.IComInterface.ComMethod");
}
// ICustomQueryInterface
public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv)
{
if (iid == typeof(NewLibrary.IComInterface).GUID)
{
// CustomQueryInterfaceMode.Ignore is to avoid infinite loop during QI.
ppv = Marshal.GetComInterfaceForObject(this, typeof(NewLibrary.IComInterface), CustomQueryInterfaceMode.Ignore);
return CustomQueryInterfaceResult.Handled;
}
ppv = IntPtr.Zero;
return CustomQueryInterfaceResult.NotHandled;
}
// constructor
public ImprovedClass()
{
// aggregate the CCW object with the helper Inner object
_baseClassComProxy = new BaseClassComProxy(this);
_baseIComInterface = _baseClassComProxy.GetComInterface<IComInterface>();
}
~ImprovedClass()
{
Dispose();
Console.WriteLine("ImprovedClass finalized.");
}
// IDispose
public void Dispose()
{
// we may have recicular COM references to itself
// e.g., via _baseIComInterface
// make sure to release all references
if (_baseIComInterface != null)
{
Marshal.ReleaseComObject(_baseIComInterface);
_baseIComInterface = null;
}
if (_baseClassComProxy != null)
{
_baseClassComProxy.Dispose();
_baseClassComProxy = null;
}
}
// for testing
public void InvokeComMethod()
{
((NewLibrary.IComInterface)this).ComMethod(null);
}
}
#region BaseClassComProxy
// Inner as aggregated object
class BaseClassComProxy :
ICustomQueryInterface,
IDisposable
{
WeakReference _outer; // avoid circular refs between outer and inner object
Type[] _interfaces; // the base's private COM interfaces are here
IntPtr _unkAggregated; // aggregated proxy
public BaseClassComProxy(object outer)
{
_outer = new WeakReference(outer);
_interfaces = outer.GetType().BaseType.GetInterfaces();
var unkOuter = Marshal.GetIUnknownForObject(outer);
try
{
// CreateAggregatedObject does AddRef on this
// se we provide IDispose for proper shutdown
_unkAggregated = Marshal.CreateAggregatedObject(unkOuter, this);
}
finally
{
Marshal.Release(unkOuter);
}
}
public T GetComInterface<T>() where T : class
{
// cast an outer's base interface to an equivalent outer's interface
return (T)Marshal.GetTypedObjectForIUnknown(_unkAggregated, typeof(T));
}
public void GetComInterface<T>(out T baseInterface) where T : class
{
baseInterface = GetComInterface<T>();
}
~BaseClassComProxy()
{
Dispose();
Console.WriteLine("BaseClassComProxy object finalized.");
}
// IDispose
public void Dispose()
{
if (_outer != null)
{
_outer = null;
_interfaces = null;
if (_unkAggregated != IntPtr.Zero)
{
Marshal.Release(_unkAggregated);
_unkAggregated = IntPtr.Zero;
}
}
}
// ICustomQueryInterface
public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv)
{
// access to the outer's base private COM interfaces
if (_outer != null)
{
var ifaceGuid = iid;
var iface = _interfaces.FirstOrDefault((i) => i.GUID == ifaceGuid);
if (iface != null && iface.IsImport)
{
// must be a COM interface with ComImport attribute
var unk = Marshal.GetComInterfaceForObject(_outer.Target, iface, CustomQueryInterfaceMode.Ignore);
if (unk != IntPtr.Zero)
{
ppv = unk;
return CustomQueryInterfaceResult.Handled;
}
}
}
ppv = IntPtr.Zero;
return CustomQueryInterfaceResult.Failed;
}
}
#endregion
}
class Program
{
static void Main(string[] args)
{
// test
var improved = new NewLibrary.ImprovedClass();
improved.InvokeComMethod();
//// COM client
//var unmanagedObject = (ISimpleUnmanagedObject)Activator.CreateInstance(Type.GetTypeFromProgID("Noseratio.SimpleUnmanagedObject"));
//unmanagedObject.InvokeComMethod(improved);
improved.Dispose();
improved = null;
// test ref counting
GC.Collect(generation: GC.MaxGeneration, mode: GCCollectionMode.Forced, blocking: false);
Console.WriteLine("Press Enter to exit.");
Console.ReadLine();
}
// COM test client interfaces
[ComImport(), Guid("2EA68065-8890-4F69-A02F-2BC3F0418561")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
internal interface ISimpleUnmanagedObject
{
void InvokeComMethod([In, MarshalAs(UnmanagedType.Interface)] object arg);
void InvokeComMethodDirect([In] IntPtr comInterface);
}
}
}
BaseClass.IComInterface.ComMethod
ImprovedClass.IComInterface.ComMethod
Press Enter to exit.
BaseClassComProxy object finalized.
ImprovedClass finalized.
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