在 C# 中实现 IDispatch
我正在编写一些测试代码来模拟调用后期绑定 COM 对象的 C# 实现的非托管代码。我有一个声明为 IDispatch 类型的接口，如下所示。
[Guid("2D570F11-4BD8-40e7-BF14-38772063AAF0")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface TestInterface
{
int Test();
}
[ClassInterface(ClassInterfaceType.AutoDual)]
public class TestImpl : TestInterface
{
...
}
当我使用下面的代码调用 IDispatch 的 GetIDsOfNames 函数时
..
//code provided by Hans Passant
Object so = Activator.CreateInstance(Type.GetTypeFromProgID("ProgID.Test"));
string[] rgsNames = new string[1];
int[] rgDispId = new int[1];
rgsNames[0] = "Test";
//the next line throws an exception
IDispatch disp = (IDispatch)so;
，其中 IDispatch 定义为：
//code provided by Hans Passant
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00020400-0000-0000-C000-000000000046")]
private interface IDispatch {
int GetTypeInfoCount();
[return: MarshalAs(UnmanagedType.Interface)]
ITypeInfo GetTypeInfo([In, MarshalAs(UnmanagedType.U4)] int iTInfo, [In, MarshalAs(UnmanagedType.U4)] int lcid);
void GetIDsOfNames([In] ref Guid riid, [In, MarshalAs(UnmanagedType.LPArray)] string[] rgszNames, [In, MarshalAs(UnmanagedType.U4)] int cNames, [In, MarshalAs(UnmanagedType.U4)] int lcid, [Out, MarshalAs(UnmanagedType.LPArray)] int[] rgDispId);
}
抛出 InvalidCastException 。是否可以将 ac# 接口转换为 IDispatch？
I'm writing some test code to emulate unmanaged code calling my c# implementation of a late binding COM object. I have an interface that is declared as an IDispatch type as below.
[Guid("2D570F11-4BD8-40e7-BF14-38772063AAF0")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface TestInterface
{
int Test();
}
[ClassInterface(ClassInterfaceType.AutoDual)]
public class TestImpl : TestInterface
{
...
}
When I use the code below to call IDispatch's GetIDsOfNames function
..
//code provided by Hans Passant
Object so = Activator.CreateInstance(Type.GetTypeFromProgID("ProgID.Test"));
string[] rgsNames = new string[1];
int[] rgDispId = new int[1];
rgsNames[0] = "Test";
//the next line throws an exception
IDispatch disp = (IDispatch)so;
Where IDispatch is defined as:
//code provided by Hans Passant
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00020400-0000-0000-C000-000000000046")]
private interface IDispatch {
int GetTypeInfoCount();
[return: MarshalAs(UnmanagedType.Interface)]
ITypeInfo GetTypeInfo([In, MarshalAs(UnmanagedType.U4)] int iTInfo, [In, MarshalAs(UnmanagedType.U4)] int lcid);
void GetIDsOfNames([In] ref Guid riid, [In, MarshalAs(UnmanagedType.LPArray)] string[] rgszNames, [In, MarshalAs(UnmanagedType.U4)] int cNames, [In, MarshalAs(UnmanagedType.U4)] int lcid, [Out, MarshalAs(UnmanagedType.LPArray)] int[] rgDispId);
}
An InvalidCastException is thrown. Is it possible to cast a c# interface into IDispatch?
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您需要使用 regasm 注册程序集，并且需要使用 [ComVisible] 属性标记要从 COM 访问的类。您可能还需要使用 tlbexp（生成）和 tregsvr 来生成和注册类型库来注册它。
另外（从 Win32 的角度来看）“disp = (IDispatch) obj”与“disp = obj as IDispatch”不同 - 使用“as”运算符实际上调用对象上的 QueryInterface 方法来获取指向所请求接口的指针，而不是尝试将对象强制转换为接口。
最后，使用 c# 的“动态”类型可能会更接近其他人访问您的类所做的事情。
You need to register you assembly with regasm, and you need to mark the classes you want to access from COM with the [ComVisible] attribute. You may also need to generate and register a type-library using tlbexp (to generate) and tregsvr to register it.
Also (from a Win32 perspective) "disp = (IDispatch) obj" is not the same as "disp = obj as IDispatch" - using the 'as' operator actually calls the QueryInterface method on the object to get the pointer to the requested interface, instead of trying to cast an object to to the interface.
Lastly using c#'s 'dynamic' type will probably be closer to what the other guys are doing to access your class.
您应该能够使用 COM 类型的反射来获取方法列表。
You should just be able to use reflection on the COM type to get the list of methods.