套接字编程，编码/解码数据/文本，更具体的特殊字符通过套接字发送和接收

Question

Win 10 64 位 C++ 中的服务器：

const int BufLen = 1024;
char RecvBuf[BufLen];
int result;
char SendBuf[BufLen] ;

const int PORT = 27015;
const char* HOST = "127.0.0.1";

int main()
{
    //SetConsoleOutputCP(65001);
    std::cout << "Hello World!\n";
    //std::cout << "á" << std::endl;
    WSADATA wsaData; 
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);   if (iResult != NO_ERROR) {
        printf("Error at WSAStartup()\n");     
        return 1;
    }
    // Create a SOCKET for listening for   // incoming connection requests. 
    SOCKET ListenSocket;
    ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (ListenSocket == INVALID_SOCKET) {
        printf("Error at socket(): %ld\n", WSAGetLastError());    
        WSACleanup();  
        return 1;
    
    }
    // The sockaddr_in structure specifies the address family,
    // IP address, and port for the socket that is being bound.

    sockaddr_in service;

    service.sin_family = AF_INET;
    //service.sin_addr.s_addr = inet_addr("127.0.0.1");
    inet_pton(AF_INET, HOST, &service.sin_addr);
    service.sin_port = htons(PORT);

    if (bind(ListenSocket, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR) { 
        printf("bind() failed.\n"); 
        closesocket(ListenSocket); 
        WSACleanup(); 
        return 1;
    }
    // Listen for incoming connection requests.
    // on the created socket
    if (listen(ListenSocket, 1) == SOCKET_ERROR) { 
        printf("Error listening on socket.\n");
        closesocket(ListenSocket); WSACleanup();
        return 1; 
    }

    // Create a SOCKET for accepting incoming requests. SOCKET AcceptSocket; printf("Waiting for client to connect...\n");
    SOCKET AcceptSocket;
    printf("Waiting for client to connect...\n");

    // Accept the connection.
    AcceptSocket = accept( ListenSocket, NULL, NULL );
    if (AcceptSocket == INVALID_SOCKET) {
        printf("accept failed: %d\n", WSAGetLastError()); 
        closesocket(ListenSocket);
        WSACleanup(); 
        return 1;
    }
    else printf("Client connected.\n");
    // Call the recvfrom function to receive datagrams 
    // on the bound socket.
    
    printf("Receiving datagrams...\n");
    result = recv(AcceptSocket, RecvBuf, BufLen, 0);
   
    printf("%d\n", result);
    std::cout << "Received:" << RecvBuf << std::endl;
    printf("%d", sizeof(RecvBuf));
    //strcpy_s(SendBuf, "Helloéáőúóü");
    printf("\n\n\n\n");
    strcpy_s(SendBuf, "abcá");
    std::cout << SendBuf << std::endl;
    result = send(AcceptSocket, SendBuf, BufLen, 0);
    printf("\nAfter sending: %d\n", result);
    std::cout << SendBuf;

Java 客户端：

 var socket = new Socket("127.0.0.1", 27015);
        //sending to the server
        var out = new PrintWriter(socket.getOutputStream(), true);
        out.println("Helloá");
        //receive from server
        var in = new InputStreamReader(socket.getInputStream());
        BufferedReader br = new BufferedReader(in);
        char[] buffer = new char[1024];
        int count = br.read(buffer, 0, 20);
        String reply = new String(buffer, 0, count);
        System.out.println(reply);

Python 客户端：

HOST = "127.0.0.1"
PORT =  27015
clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
clientSocket.connect((HOST, PORT))
clientSocket.send("JAASFSKF".encode('utf-8'))
msg = clientSocket.recv(1024)
print(msg)
msg = msg.decode('utf-8')
print(msg)
clientSocket.close()

用特殊字符进行了一些实验，但客户端或服务器都无法处理。

java客户端结果： encoding done with utf-8 python 应用程序抛出异常，因为它无法解码从套接字接收的数据： Python 3.9.5 我试图以不同的编码保存服务器，但我认为情况并非如此，可能需要对套接字声明进行一些更改。 客户端与服务器是同一台机器。 这是我的实际问题，要克服这个问题

Answer 1

TCP 套接字携带字节流，无需解释。没有“特殊字符”。

您的 C++ 代码显然是以字节为单位的；您的 Python 和 Java 代码期望这些字节代表编码为 UTF-8 的“字符”。这是设计不匹配。

如果您的意图是通信使用 UTF-8，则 C++ 代码应显式转换为/从 UTF-8。

---

此外，TCP 中没有“消息”。这是一个字节流协议。您需要一个约定，以便每一端都可以确定它是否收到了您的应用程序想要考虑的消息。

如果一方发送“xyz”（并没有立即关闭连接），另一方怎么知道“z”是最后一个字符？

由于您正在处理字符，一种方法是确保所有内容都以换行符“\n”终止。您可以使用面向行的方法。