在 c# 程序中，我想使用 WM_COPYDATA 和 SendMessage 来与遗留的 c++/cli MFC 应用程序通信。

我想传递一个包含字符串对象的托管结构。

我可以找到与 SendMessage 一起使用的 c++ 应用程序的句柄。

我不知道的一点是如何在另一端编码和读取结构及其字符串。特别是因为它包含非 blittables。

大家觉得这可行吗？ 我会继续努力，但会感谢做过此类事情的人告诉我它是否行不通。

这里有一些演示代码，如果它是一个 c++/cli 程序，它不难运行。 但是，我希望它位于 .Net 类库中，以便可以轻松地重复使用。

//Quick demonstation code only, not correctly styled
int WINAPI WinMain(HINSTANCE hInstance,
                 HINSTANCE hPrevInstance,
                 LPSTR lpCmdLine,
                 int nCmdShow)
{               
    struct MessageInfo
    {
        int     nVersion;
        char   szTest[ 10 ];        
    };

    MessageInfo sMessageInfo;

    sMessageInfo.nVersion = 100;
    strcpy( sMessageInfo.szTest, "TEST");   

    COPYDATASTRUCT CDS;

    CDS.dwData = 1; //just for test
    CDS.cbData = sizeof( sMessageInfo );
    CDS.lpData = &sMessageInfo;

    //find running processes and send them a message
    //can't just search for "MYAPP.exe" as will be called "MYAPP.exe *32" on a 64bit machine
    array<System::Diagnostics::Process^>^allProcesses = System::Diagnostics::Process::GetProcesses();

    for each (System::Diagnostics::Process^ targetProcess in allProcesses)
    {        
        if (targetProcess->ProcessName->StartsWith("MYAPP", System::StringComparison::OrdinalIgnoreCase))
        {
            HWND handle = static_cast<HWND>(targetProcess->MainWindowHandle.ToPointer());

            BOOL bReturnValue = SendMessage( handle, WM_COPYDATA, (WPARAM)0, (LPARAM)&CDS ) == TRUE;
        }
    }

    return 0;
}

最佳答案

我有它的工作。

一种简单的方法是将结构序列化为单个字符串并传输一个字符串。 swhiSTLesoft 博客很有帮助 http://www.swhistlesoft.com/blog/2011/11/19/1636-wm_copydata-with-net-and-c

这可能足以提供简单的消息传递。 如有必要，可以在另一端重新构造该结构。

如果要按原样编码具有任意数量字符串的结构，那么它必须是固定大小，这是我没有得到的主要内容。

MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst = 9)

基本上设置大小以匹配 c++ 大小，在我们的例子中是 TCHAR szTest[ 9 ];

为了通过 WM_COPYDATA 将 .Net 结构从 c# 传输到 c++(/cli)，我必须执行以下操作:

[System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

    [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
    static extern bool SetForegroundWindow(IntPtr hWnd);

public static uint WM_COPYDATA = 74;

//from swhistlesoft
public static IntPtr IntPtrAlloc<T>(T param)
    { 
        IntPtr retval = System.Runtime.InteropServices.Marshal.AllocHGlobal(System.Runtime.InteropServices.Marshal.SizeOf(param)); 
        System.Runtime.InteropServices.Marshal.StructureToPtr(param, retval, false); 
        return (retval); 
    }

//from swhistlesoft
    public static void IntPtrFree(IntPtr preAllocated) 
    { 
        if (IntPtr.Zero == preAllocated) throw (new Exception("Go Home")); 
        System.Runtime.InteropServices.Marshal.FreeHGlobal(preAllocated); 
        preAllocated = IntPtr.Zero; 
    }

    [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
    struct COPYDATASTRUCT
    {
        public uint dwData;
        public int cbData;
        public IntPtr lpData;
    }

    /// <summary>
    /// Dot net version of AppInfo structure. Any changes to the structure needs reflecting here.
    /// struct must be a fixed size for marshalling to work, hence the SizeConst entries
    /// </summary>
    [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential, Pack = 1)]
    struct AppInfoDotNet
    {
        public int   nVersion;            

        [System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst = 9)]
        public string test;
    };

发送一个字符串:

    COPYDATASTRUCT cd = new COPYDATASTRUCT();
    cd.dwData = 2;

    cd.cbData = parameters.Length + 1;
    cd.lpData = System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi(parameters);

    IntPtr cdBuffer = IntPtrAlloc(cd);

    messageReceived = ((int)SendMessage(targetProcess.MainWindowHandle, WM_COPYDATA, IntPtr.Zero, cdBuffer)) != 0;

在 C++ 中接收字符串:

else if(pCDS->dwData == 2)
    {
        //copydata message
        CString csMessage = (LPCTSTR)pCDS->lpData;
        OutputDebugString("Copydata message received: " + csMessage);
    }

发送结构:

            AppInfoDotNet appInfo = new AppInfoDotNet();
            appInfo.test = "a test";

            COPYDATASTRUCT cds3;
            cds3.dwData = 1;
            cds3.cbData = System.Runtime.InteropServices.Marshal.SizeOf(appInfo);

            IntPtr structPtr = System.Runtime.InteropServices.Marshal.AllocCoTaskMem(System.Runtime.InteropServices.Marshal.SizeOf(appInfo));
            System.Runtime.InteropServices.Marshal.StructureToPtr(appInfo, structPtr, false);

            cds3.lpData = structPtr;

            IntPtr iPtr = System.Runtime.InteropServices.Marshal.AllocCoTaskMem(System.Runtime.InteropServices.Marshal.SizeOf(cds3));
            System.Runtime.InteropServices.Marshal.StructureToPtr(cds3, iPtr, false);

            messageReceived = ((int)SendMessage(targetProcess.MainWindowHandle, WM_COPYDATA, IntPtr.Zero, iPtr)) != 0;

            System.Runtime.InteropServices.Marshal.FreeCoTaskMem(iPtr);
            System.Runtime.InteropServices.Marshal.FreeCoTaskMem(structPtr);

在 C++ 中接收结构:

LRESULT CMainFrame::OnCopyData( WPARAM wParam, LPARAM lParam )
{
    LRESULT lResult = FALSE;

    COPYDATASTRUCT *pCDS = (COPYDATASTRUCT*)lParam;

    //Matching message type for struct
    if(pCDS->dwData == 1)
    {
        AppInfo *pAppInfo = (AppInfo*)pCDS->lpData
        lResult = true;
    }

请注意这是演示代码，需要在样式、异常处理等方面进行改进...

关于C# 到 C++ 进程，WM_COPYDATA 传递带有字符串的结构，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12743962/