IUnKnown接口定义
[ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
Guid("00000000-0000-0000-C000-000000000046")]
public interface IUnknown
{
[PreserveSig]
int QueryInterface(ref Guid riid, out IntPtr ppvObject);
[PreserveSig]
uint AddRef();
[PreserveSig]
uint Release();
}Class1定义
class Class1 : IUnknown
{
public int QueryInterface(ref Guid riid, out IntPtr ppvObject)
{
throw new Exception("The method or operation is not implemented.");
}
public uint AddRef()
{
throw new Exception("The method or operation is not implemented.");
}
public uint Release(
{
throw new Exception("The method or operation is not implemented.");
}
}
或者
class Class1 : IUnknown
{
int IUnknown.QueryInterface(ref Guid riid, out IntPtr ppvObject)
{
throw new Exception("The method or operation is not implemented.");
}
uint IUnknown.AddRef()
{
throw new Exception("The method or operation is not implemented.");
}
uint IUnknown.Release()
{
throw new Exception("The method or operation is not implemented.");
}
}主程序 IUnknown Class1 = new Class1(); 在创建的时候，并不会调用AddRef()
.Net下不是这么玩的。
.Net已经有了垃圾回收机制，不需要使用COM的引用计数。
当一个类被.Net的发表为COM对象，.Net会自动帮你实现IUnknown，并帮你管理引用计数。
[assembly: ComVisible(true)] //<--
[InterfaceType( ComInterfaceType.InterfaceIsIUnknown)] //不写也可以，会默认为dual
interface A
{
//作为COM发表后，A已经继承IUnknown了。
}
woshi_ziyu?2011-12-14IUnknown::AddRef method
Increments the reference count for an interface on an object. This method should be called for every new copy of a pointer to an interface on an object.
Syntax
ULONG AddRef();
Parameters
This method has no parameters.
Return value
The method returns the new reference count. This value is intended to be used only for test purposes.
Remarks
Objects use a reference counting mechanism to ensure that the lifetime of the object includes the lifetime of references to it. You use AddRef to stabilize a copy of an interface pointer. It can also be called when the life of a cloned pointer must extend beyond the lifetime of the original pointer. The cloned pointer must be released by calling IUnknown::Release.
The internal reference counter that AddRef maintains should be a 32-bit unsigned integer.
Notes to Callers
Call this method for every new copy of an interface pointer that you make. For example, if you are passing a copy of a pointer back from a method, you must call AddRef on that pointer. You must also call AddRef on a pointer before passing it as an in-out parameter to a method; the method will call IUnknown::Release before copying the out-value on top of it.