c# - 使用命名管道的两种 C++ 到 C# 通信

Question

我正在尝试在 VC++ 6 应用程序和 C# 应用程序之间进行双向通信。我正在使用命名管道。在我的 C++ 代码中，我可以从 C# 客户端读取消息，但随后服务器“死机”，我必须重新启动它。

我想要做的是让 C# 应用程序连接到 C++ 应用程序，请求状态，然后 C++ 应用程序关闭并检查状态，然后返回“忙”或“空闲”。

我无法将任何内容写回 C# 客户端，因为它表示连接已关闭。我注释掉的一些东西是我已经尝试过的东西。

C++ 代码(作为线程启动)

UINT CNamedPipe::StartNamedPipeServer()
{
LPTSTR lpszPipename = "\\\\.\\pipe\\SAPipe"; 
    HANDLE hPipe; 
    BOOL flg;
    DWORD dwWrite,dwRead;
    char szServerUpdate[200];
    char szClientUpdate[200];

    hPipe = CreateNamedPipe (    lpszPipename, 
                                PIPE_ACCESS_DUPLEX,
                                PIPE_TYPE_MESSAGE | 
                                PIPE_READMODE_MESSAGE | 
                                PIPE_NOWAIT,                    //changed from nowait
                                PIPE_UNLIMITED_INSTANCES,    // max. instances 
                                BUFSIZE,                    // output buffer size 
                                BUFSIZE,                    // input buffer size 
                                PIPE_TIMEOUT,                // client time-out 
                                NULL);                        // no security attribute 

    if (hPipe == INVALID_HANDLE_VALUE) 
        return 0;

    ConnectNamedPipe(hPipe, NULL);

    while(m_bServerActive)  //This seems to work well ....
    {

        //Read from client
        flg = ReadFile(hPipe,szClientUpdate,strlen(szClientUpdate),&dwRead, NULL);

        if(flg) //Read something from the client!!!!
        {
            CString csMsg,csTmp;

            for(int i=0;i<dwRead;i++){
                csTmp.Format("%c",szClientUpdate[i]);
                csMsg += csTmp;
            }


            AfxMessageBox("Client message: " + csMsg);

            strcpy( szServerUpdate,"busy");

            //Write status to Client
            flg = WriteFile(hPipe, szServerUpdate, strlen(szServerUpdate), &dwWrite, NULL);

            EndServer();
            StartServer();
        }

    }

    return 0;

C#代码:

public void ThreadStartClient(object obj)
    {
        // Ensure that we only start the client after the server has created the pipe
        ManualResetEvent SyncClientServer = (ManualResetEvent)obj;

        // Only continue after the server was created -- otherwise we just fail badly
        // SyncClientServer.WaitOne();

        using (NamedPipeClientStream pipeStream = new NamedPipeClientStream(".", "SAPipe"))
        {
            // The connect function will indefinately wait for the pipe to become available
            // If that is not acceptable specify a maximum waiting time (in ms)
            pipeStream.Connect();

            //Write from client to server
           using (StreamWriter sw = new StreamWriter(pipeStream))
            {
                sw.WriteLine("What's your status?");
           }

            //Read server reply
            /*using (StreamReader sr = new StreamReader(pipeStream))
            {
                string temp = "";
                temp = sr.ReadLine();   //Pipe is already closed here ... why?

                MessageBox.Show(temp);

            }*/

            //pipeStream.Close();

        }
    }
}

Answer 1

处置 StreamWriter 或 StreamReader 将关闭底层流。

因此，您的 using 语句将导致流关闭。

    public void ThreadStartClient(object obj)
    {
            // Ensure that we only start the client after the server has created the pipe
            ManualResetEvent SyncClientServer = (ManualResetEvent)obj;

            // Only continue after the server was created -- otherwise we just fail badly
            // SyncClientServer.WaitOne();

            using (NamedPipeClientStream pipeStream = new NamedPipeClientStream(".", "SAPipe"))
            {
                // The connect function will indefinately wait for the pipe to become available
                // If that is not acceptable specify a maximum waiting time (in ms)
                pipeStream.Connect();


                //Write from client to server
                StreamWriter sw = new StreamWriter(pipeStream))
                sw.WriteLine("What's your status?");

                //Read server reply
                StreamReader sr = new StreamReader(pipeStream)
                string temp = "";
                temp = sr.ReadLine();   //Pipe is already closed here ... why?

                MessageBox.Show(temp);
            }
    }

还应注意，因为您将流包装在 using 语句中，所以不需要注释掉的 pipeStream.Close() 函数。