《QT从基础到进阶·十六》QT实现客户端和服务端的简单交互

QT版本：5.15.2
VS版本：2019

客户端程序主要包含三块：连接服务器，发送消息，关闭客户端
服务端程序主要包含三块：打开消息监听，接收消息并反馈，关闭服务端

1、先打开服务端监听功能

void TCPServer::listen()
{
    initWsaData();
    //创建套接字
    sock = socket(AF_INET, SOCK_STREAM, 0);
    //创建地址簇对象
    sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(9888);
    sin.sin_addr.s_addr = htonl(INADDR_ANY);
    //绑定套接字
    int bindStatus = ::bind(sock, (struct sockaddr*)&sin, sizeof(sin));
    if (bindStatus == -1) {
        qDebug() << "socket bind failed!" << endl;
        ui.textBrowser->setText("socket bind failed!");
        return;
    }
    else {
        qDebug() << "socket bind success!" << endl;
        ui.textBrowser->setText("socket bind success!");
    }
    //将套接字设为监听模式，等待客户端连接
    int listenStatus = ::listen(sock, 128);
    if (listenStatus == -1) {
        qDebug() << "listen failed" << endl;
        ui.textBrowser->setText("listen failed");
        return;
    }
    else {
        qDebug() << "set listen success, server is listening..." << endl;
        ui.textBrowser->setText("set listen success, server is listening...");
    }
    //收到请求主后，接收连接请求，返回一个对应此次连接的新套接字
    //接受连接请求
    sockaddr_in sinAccept;
    int len = sizeof(sin);
    newSock = accept(sock, (struct sockaddr*)&sinAccept, &len);
    if (newSock == SOCKET_ERROR) {
        qDebug() << "connect failed" << endl;
        ui.textBrowser->setText("connect failed");
        return;
    }
    else {
        qDebug() << "connect success, ready to recv data" << endl;
        ui.textBrowser->setText("connect success, ready to recv data");
    }
}

2、点击客户端connect连接服务端

void TCPClient::Connect(const std::string ip, const int port)
{
    bool res = initWsaData(); //初始化套接字库
    if (!res) return;

    //常用协议族：AF_UNIX（本机通信）AF_INET（TCP/IP – IPv4）AF_INET6（TCP/IP – IPv6）
    //套接字类型：SOCK_STREAM（TCP流）SOCK_DGRAM（UDP数据报）SOCK_RAW（原始套接字）
    //protocol”一般设置为“0”
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock == SOCKET_ERROR) {
        qDebug() << "Failed to create socket" << endl;
        ui.textBrowser->setText("Failed to create socket");
        return;
    }
    else {
        qDebug() << "Socket created successfully" << endl;
        ui.textBrowser->setText("Socket created successfully");
    }

    //设置地址
    sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(port);
    sin.sin_addr.s_addr = inet_addr(ip.c_str());

    //连接服务器
    int connStatus = ::connect(sock, (struct sockaddr*)&sin, sizeof(sin));
    if (connStatus == -1) {
        qDebug() << "Failed to connect to the server" << endl;
        ui.textBrowser->setText("Failed to connect to the server");
        return;
    }
}

3、在客户端输入消息点击send发送到服务端

void TCPClient::DataTransmission()
{
    string msg = ui.lineEdit->text().toStdString();
    /*char sendBuf[MAX_MSG_SIZE];
    memset(sendBuf, 0, MAX_MSG_SIZE)*/;
    
    int sendStatus = send(sock, msg.c_str(), MAX_MSG_SIZE, 0);
    if (sendStatus == 0) {
        qDebug() << "Failed to send information" << endl;
        ui.textBrowser->setText("Failed to send information");

        //关闭套接字及套接字库
        closesocket(sock);
        WSACleanup();
        return;
    }

    char recvBuf[MAX_MSG_SIZE];
    memset(recvBuf, 0, MAX_MSG_SIZE);
    int recvStatus = recv(sock, recvBuf, MAX_MSG_SIZE, 0);
    if (recvStatus == -1) {
        qDebug() << "Failed to receive message" << endl;
        ui.textBrowser->setText("Failed to receive message");

        //关闭套接字及套接字库
       /* closesocket(sock);
        WSACleanup();*/
        return;
    }
    else {
        qDebug() << "Server information:" << recvBuf << endl;
        string msg = "---------Server information:" + string(recvBuf);
        ui.textBrowser->setText(QString::fromStdString(msg));
    }
}

4、在服务端点击send接收客户端消息并通知客户端已收到消息

void TCPServer::DataTransmission()
{
    //用新建立的套接字和客户端进行通信
    char recvBuf[MAX_MSG_SIZE];
    char sendBuf[MAX_MSG_SIZE];
    memset(recvBuf, 0, MAX_MSG_SIZE);
    memset(sendBuf, 0, MAX_MSG_SIZE);
    if (true) {
        int recvStatus = recv(newSock, recvBuf, MAX_MSG_SIZE, 0);
        if (recvStatus == -1) {
            qDebug() << "recv data failed" << endl;
            ui.textBrowser->setText("recv data failed");
            closesocket(sock);
            closesocket(newSock);
            WSACleanup();
            return;
        }
        else {
            qDebug() << "recv client new msg:" << recvBuf << endl;
            string msg = "--------------recv client new msg:" + string(recvBuf);
            ui.textBrowser->setText(QString::fromStdString(msg));
        }
        /*qDebug() << "请输入回复消息:";
        cin >> sendBuf;*/
        string sendMsg = "has recv msg-------";
        int sendStatus = send(newSock, sendMsg.c_str(), sizeof(sendBuf), 0);
        if (sendStatus == -1) {
            qDebug() << "msg send failed" << endl;
            ui.textBrowser->setText("msg send failed");
            closesocket(sock);
            closesocket(newSock);
            WSACleanup();
            return;
        }
    }
}