我剛剛發表了一篇關於如何做的CodeProject文章。本文提供了一個小巧的C#DispatchUtility
輔助類,它很容易包含在其他項目中。在內部,它使用IDispatch和.NET的TypeToTypeInfoMarshaler的自定義聲明將IDispatch的ITypeInfo轉換爲豐富的.NET Type實例。
在你的例子中,你可以調用DispatchUtility.GetType(obj, true)
來取回一個.NET Type實例,然後你可以調用GetMembers。
FWIW,DispatchUtility
對IDispatch.GetTypeInfo的聲明與您的聲明幾乎完全相同。但是,在調用GetTypeInfo時,它會傳遞LOCALE_SYSTEM_DEFAULT(2048)而不是0作爲lcid參數。也許GetTypeInfo爲您的disp.GetTypeInfo(0, 0, out t)
調用返回了失敗HRESULT。既然你用[PreserveSig]
來聲明它,你需要檢查它的結果(例如,通過調用Marshal.ThrowExceptionForHR
)。
這裏的DispatchUtility
類評論最多的去除的一個版本:
using System;
using System.Runtime.InteropServices;
using System.Reflection;
public static class DispatchUtility
{
private const int S_OK = 0; //From WinError.h
private const int LOCALE_SYSTEM_DEFAULT = 2 << 10; //From WinNT.h == 2048 == 0x800
public static bool ImplementsIDispatch(object obj)
{
bool result = obj is IDispatchInfo;
return result;
}
public static Type GetType(object obj, bool throwIfNotFound)
{
RequireReference(obj, "obj");
Type result = GetType((IDispatchInfo)obj, throwIfNotFound);
return result;
}
public static bool TryGetDispId(object obj, string name, out int dispId)
{
RequireReference(obj, "obj");
bool result = TryGetDispId((IDispatchInfo)obj, name, out dispId);
return result;
}
public static object Invoke(object obj, int dispId, object[] args)
{
string memberName = "[DispId=" + dispId + "]";
object result = Invoke(obj, memberName, args);
return result;
}
public static object Invoke(object obj, string memberName, object[] args)
{
RequireReference(obj, "obj");
Type type = obj.GetType();
object result = type.InvokeMember(memberName,
BindingFlags.InvokeMethod | BindingFlags.GetProperty,
null, obj, args, null);
return result;
}
private static void RequireReference<T>(T value, string name) where T : class
{
if (value == null)
{
throw new ArgumentNullException(name);
}
}
private static Type GetType(IDispatchInfo dispatch, bool throwIfNotFound)
{
RequireReference(dispatch, "dispatch");
Type result = null;
int typeInfoCount;
int hr = dispatch.GetTypeInfoCount(out typeInfoCount);
if (hr == S_OK && typeInfoCount > 0)
{
dispatch.GetTypeInfo(0, LOCALE_SYSTEM_DEFAULT, out result);
}
if (result == null && throwIfNotFound)
{
// If the GetTypeInfoCount called failed, throw an exception for that.
Marshal.ThrowExceptionForHR(hr);
// Otherwise, throw the same exception that Type.GetType would throw.
throw new TypeLoadException();
}
return result;
}
private static bool TryGetDispId(IDispatchInfo dispatch, string name, out int dispId)
{
RequireReference(dispatch, "dispatch");
RequireReference(name, "name");
bool result = false;
Guid iidNull = Guid.Empty;
int hr = dispatch.GetDispId(ref iidNull, ref name, 1, LOCALE_SYSTEM_DEFAULT, out dispId);
const int DISP_E_UNKNOWNNAME = unchecked((int)0x80020006); //From WinError.h
const int DISPID_UNKNOWN = -1; //From OAIdl.idl
if (hr == S_OK)
{
result = true;
}
else if (hr == DISP_E_UNKNOWNNAME && dispId == DISPID_UNKNOWN)
{
result = false;
}
else
{
Marshal.ThrowExceptionForHR(hr);
}
return result;
}
[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("00020400-0000-0000-C000-000000000046")]
private interface IDispatchInfo
{
[PreserveSig]
int GetTypeInfoCount(out int typeInfoCount);
void GetTypeInfo(int typeInfoIndex, int lcid, [MarshalAs(UnmanagedType.CustomMarshaler,
MarshalTypeRef = typeof(System.Runtime.InteropServices.CustomMarshalers.TypeToTypeInfoMarshaler))] out Type typeInfo);
[PreserveSig]
int GetDispId(ref Guid riid, ref string name, int nameCount, int lcid, out int dispId);
// NOTE: The real IDispatch also has an Invoke method next, but we don't need it.
}
}
謝謝。事實上,這個組件是一個內置腳本語言的商業應用程序。其成員的完整列表在運行時確定。它沒有類型庫。 – 2010-11-13 06:45:31
@HansPassant我碰到了這裏的腥第三個參數的解釋:https://www.codeproject.com/articles/523417/reflection-with-idispatch-based-com-objects – jnm2 2017-02-11 13:41:13