c# - 如何使用 SendMessage (WM_COPYDATA) 从 C# 向 C++ (MESSAGE ONLY WINDOW) 发送消息？

Question

编辑:我已修复这里是我的工作完整代码，可以为新 friend 树立榜样，我的原始问题也在下面。

在代码之前让我向您介绍一些文档(按顺序):

https://learn.microsoft.com/en-us/windows/win32/winmsg/about-messages-and-message-queues#message-routing

https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-sendmessage

https://learn.microsoft.com/en-us/windows/win32/winmsg/window-features#message-only-windows

https://learn.microsoft.com/en-us/windows/win32/dataxchg/using-data-copy

http://pinvoke.net/default.aspx/Structures/COPYDATASTRUCT.html

C#程序

using System;
using System.Windows.Forms;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Program
{

    public partial class Form1 : Form
    {

        [DllImport("user32.dll")]
        static extern long SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        static extern IntPtr FindWindow(string classname, string windowname);


        [StructLayout(LayoutKind.Sequential)]
        struct COPYDATASTRUCT
        {
            public uint dwData;
            public int cbData;
            public IntPtr lpData;
        }
        public static IntPtr IntPtrAlloc<T>(T param)
        {
            IntPtr retval = Marshal.AllocHGlobal(Marshal.SizeOf(param));
            Marshal.StructureToPtr(param, retval, false);
            return (retval);
        }

        public static void IntPtrFree(IntPtr preAllocated)
        {
            if (IntPtr.Zero == preAllocated) throw (new Exception("Go Home"));
            Marshal.FreeHGlobal(preAllocated); preAllocated = IntPtr.Zero;
        }

        const int WM_COPYDATA = 0x004A;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Thread.Sleep(3000);

            string message = "This is a test";
            IntPtr hWnd = FindWindow("MyClass", "MyTitle");
            if (hWnd == IntPtr.Zero)
            {
                MessageBox.Show("couldn't find the window");
            }
            else
            {
                COPYDATASTRUCT cds;
                cds.dwData = 1;
                cds.cbData = message.Length + 1;
                cds.lpData = Marshal.StringToHGlobalAnsi(message);
                IntPtr cdsBuffer = IntPtrAlloc(cds);
                SendMessage(hWnd, WM_COPYDATA, IntPtr.Zero, cdsBuffer);
                IntPtrFree(cds.lpData);
                IntPtrFree(cdsBuffer);
            }

        }

    }
}

C++程序

#include <iostream>
#include <Windows.h>
using namespace std;


LRESULT CALLBACK WindProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
    if (Msg == WM_COPYDATA)
    {
        PCOPYDATASTRUCT data = (PCOPYDATASTRUCT)lParam;
        MessageBoxA(hWnd, (LPSTR)data->lpData, "info", 0); // The character set depends on the characters you send
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hWnd, Msg, wParam, lParam);
}


int main(){
    
    WNDCLASSEX wcx = { 0 };
    wcx.cbSize = sizeof(WNDCLASSEX);
    wcx.lpfnWndProc = WindProc;
    wcx.hInstance = GetModuleHandle(NULL);
    wcx.lpszClassName = TEXT("MyClass");
    RegisterClassEx(&wcx);
    HWND hWnd = CreateWindowEx(0, TEXT("MyClass"), TEXT("MyTitle"), 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, GetModuleHandle(NULL), NULL);


    MSG message;
    for(int i = 0; i < 1000; i++)
    {
        std::cout << "working" << std::endl;
        Sleep(2 * 1000);
        if(PeekMessage(&message, NULL, 0, 0, PM_NOREMOVE))
        {
            break;
        }
    }

    int x;
    cout<<"got it!";
    cin>>x;
    return 0;
}

原始问题:

我有一个 C# 应用程序，我想与我在 C# 应用程序中创建的 C++ 进程进行通信。

我手头有一个代码，我想它应该可以工作，但它没有。 C++ 应用程序根本无法获取该消息。

我的 C# 程序:

namespace ScannerGUI
{

    public partial class Form1 : Form
    {
        
        [return: MarshalAs(UnmanagedType.Bool)]
        [DllImport("user32.dll")]
        static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);


        [StructLayout(LayoutKind.Sequential)]
        struct COPYDATASTRUCT
        {
            public uint dwData;
            public int cbData;
            public IntPtr lpData;
        }
        public static IntPtr IntPtrAlloc<T>(T param)
        {
            IntPtr retval = Marshal.AllocHGlobal(Marshal.SizeOf(param));
            Marshal.StructureToPtr(param, retval, false);
            return (retval);
        }

        public static void IntPtrFree(IntPtr preAllocated)
        {
            if (IntPtr.Zero == preAllocated) throw (new Exception("Go Home"));
            Marshal.FreeHGlobal(preAllocated); preAllocated = IntPtr.Zero;
        }

        const int WM_COPYDATA = 0x004A;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //creating child process

            var prcsInfo = new ProcessStartInfo
            {
                UseShellExecute=true,
                CreateNoWindow = false,
                FileName = "main.exe",
            };
            
            Process myProcess = Process.Start(prcsInfo);

            ChildProcessTracker.AddProcess(myProcess);

            Thread.Sleep(3000);

            string message = "This is a test";
            IntPtr hWnd = myProcess.Handle;
            if (hWnd == IntPtr.Zero)
            {
                MessageBox.Show("couldn't find the process");
            }
            else
            {
                COPYDATASTRUCT cds;
                cds.dwData = 1;
                cds.cbData = message.Length + 1;
                cds.lpData = Marshal.StringToHGlobalAnsi(message);
                IntPtr cdsBuffer = IntPtrAlloc(cds);
                PostMessage(hWnd, WM_COPYDATA, IntPtr.Zero, cdsBuffer);
                IntPtrFree(cds.lpData);
                IntPtrFree(cdsBuffer);
            }

        }

    }
}

我的 C++ 应用程序(main.exe):

int main(){
    

    MSG message;
    for(int i = 0; i < 1000; i++)
    {
        std::cout << "working" << std::endl;
        Sleep(2 * 1000);
        if(PeekMessage(&message, NULL, 0, 0, PM_NOREMOVE))
        {
            break;
        }
    }

    int x;
    cout<<"got it!";
    cin>>x;
    return 0;
}

当我启动 C# 程序时。没有错误，什么都没有。与 C++ 相同，没有错误，什么也没有，但永远不会破坏 for 循环 :(

感谢大家的宝贵时间。

Answer 1

首先，Process.Handle是进程的句柄而不是窗口。

其次，由于您的 main.exe 是一个控制台应用程序，并且它只有一个控制台窗口，因此您只能使用 MainWindowHandle 获取控制台窗口的句柄。但是，控制台不属于main.exe，所以不能使用PeekMessage来处理发送到控制台窗口的消息。 控制台窗口由控制台子系统 csrss.exe 所有(参见 https://stackoverflow.com/a/28248281/10611792 )。您应该为您的 C++ 应用程序创建自己的窗口，或者创建一个 Message-Only window 。然后，您可以使用 FindWindow 在 C# 中获取窗口句柄:

public partial class Form1 : Form
{
    [DllImport("user32.dll")]
    static extern long SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll",CharSet = CharSet.Unicode)]
    static extern IntPtr FindWindow(string classname, string windowname);
    ...
    private void Form1_Load(object sender, EventArgs e)
    {
        ...
        Thread.Sleep(3000);

        string message = "This is a test";
        IntPtr hWnd = FindWindow("MyClass", "MyTitle");
        if (hWnd == IntPtr.Zero)
        {
            MessageBox.Show("couldn't find the process");
        }
        else
        {
            COPYDATASTRUCT cds;
            cds.dwData = 1;
            cds.cbData = message.Length + 1;
            cds.lpData = Marshal.StringToHGlobalAnsi(message);
            IntPtr cdsBuffer = IntPtrAlloc(cds);
            SendMessage(hWnd, WM_COPYDATA, IntPtr.Zero, cdsBuffer);
            IntPtrFree(cds.lpData);
            IntPtrFree(cdsBuffer);
        }

    }
}

C++:

LRESULT CALLBACK WindProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
    if (Msg == WM_COPYDATA)
    {
        PCOPYDATASTRUCT data = (PCOPYDATASTRUCT)lParam;
        MessageBoxA(hWnd, (LPSTR)data->lpData, "info", 0); // The character set depends on the characters you send
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hWnd, Msg, wParam, lParam);
}
int main() {

    WNDCLASSEX wcx = { 0 };
    wcx.cbSize = sizeof(WNDCLASSEX);
    wcx.lpfnWndProc = WindProc;
    wcx.hInstance = GetModuleHandle(NULL);
    wcx.lpszClassName = TEXT("MyClass");
    RegisterClassEx(&wcx);
    HWND hWnd = CreateWindowEx(0, TEXT("MyClass"), TEXT("MyTitle"), 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, GetModuleHandle(NULL), NULL);

    MSG msg;
    for (int i = 0; i < 1000; i++)
    {
        std::cout << "working" << std::endl;
        Sleep(2 * 1000);
        if (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
            break;
        }
    }

    int x;
    cout << "got it!";
    cin >> x;
    return 0;
}

另请注意，使用 SendMessage 而不是 PostMessage。

此外，您还可以选择其他IPC方法。