与Qt的Java套接字连接

Question

我正在尝试将一个非常简单的 java 套接字客户端连接到 QTcpServer。但是，当它连接时，我无法收发消息。我还尝试将 java 客户端连接到 java 服务器(运行良好)，将 Qt 服务器连接到 qt 客户端(也运行良好)。但是以某种方式混合它们不会..

这是 Java 客户端:

public class SocketClient {
    public static void main(String[] args) throws IOException {

        String hostName = "10.57.140.129";
        int portNumber = 2010;

        try (
            Socket kkSocket = new Socket(hostName, portNumber);
            PrintWriter out = new PrintWriter(kkSocket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                new InputStreamReader(kkSocket.getInputStream()));
        ) {
             BufferedReader stdIn =
                new BufferedReader(new InputStreamReader(System.in));
            String fromServer;
            String fromUser;

            while ((fromServer = in.readLine()) != null) {
                System.out.println("Server: " + fromServer);
                if (fromServer.equals("Test recieved. KKTHXBYE"))
                    break;

                fromUser = stdIn.readLine();
                if (fromUser != null) {
                    System.out.println("Client: " + fromUser);
                    out.println(fromUser);
                }
            }
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host " + hostName);
            System.exit(1);
        } catch (IOException e) {
             System.err.println("Couldn't get I/O for the connection to " +
                hostName);
            System.exit(1);
        }
    }
}

与相关的QTserver代码位:

#include "socketserver.h"

SocketServer::SocketServer(QObject *parent) :
    QTcpServer(parent) {
}

void SocketServer::StartServer(){
    if(!this->listen(QHostAddress::Any, 2010)){
        qDebug() << "Could not start server";
    }else{
        qDebug() << "Listening...";
    }
}

void SocketServer::incomingConnection(qintptr socketDescriptor){
    qDebug() << socketDescriptor << " Connecting...";
    SocketThread *thread = new SocketThread(socketDescriptor,this);
    connect(thread, SIGNAL(finished()),thread, SLOT(deleteLater()));
    connect(thread, SIGNAL(newData(QByteArray)), this, SLOT(incomeData(QByteArray)));
    thread->start();
}

void SocketServer::incomeData(QByteArray newData){
    emit sendBack(newData);
}

主题:

#include "socketthread.h"

SocketThread::SocketThread(qintptr ID, QObject *parent) :
    QThread(parent) {
    this->socketDescriptor = ID;
}

void SocketThread::run(){
    //thread starts here
    qDebug() << socketDescriptor << " Starting thread";
    socket = new QTcpSocket();
    if(!socket->setSocketDescriptor(this->socketDescriptor)){
        emit error(socket->error());
        return;
    }

    connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()), Qt::DirectConnection);
    connect(socket, SIGNAL(disconnected()), this, SLOT(disconnected()), Qt::DirectConnection);

    qDebug() << socketDescriptor << " Client Connected";
    writeBack("connected");

    exec();
}

void SocketThread::readyRead(){
    QByteArray incomeData = socket->readAll();

    qDebug() << socketDescriptor << " Data in: " << incomeData;

    emit newData(incomeData);
}

void SocketThread::writeBack(QByteArray Data){
    socket->write(Data);
}

void SocketThread::disconnected(){
    qDebug() << socketDescriptor << " Disconnected";

    socket->deleteLater();
    exit(0);
}

如前所述，客户端连接，并写入这些调试输出:924 连接……924 起始线程924客户端已连接

但是无论我尝试从客户端编写什么，它都不会使用 readyReady() 函数获取任何内容。有任何想法吗？我在写的行中是否缺少特定的结尾？ (\r\n和\0我都试过了，好像作用不大)

Answer 1

您似乎在 Java 中使用了基于行的处理，但在 C++ 中却没有:

in.readLine() 与 socket->readAll()

和

out.println(fromUser) 与 writeBack("connected");

C++ 只是从不发送 CR/LF，当另一端不希望发送 CR/LF 时这不是问题 -> readAll()。然而，Java 端确实期望(并发送)CR/LF，因为您使用了 BufferedReader.readLine() 和 BufferedWriter.writeln()。

决定是否需要基于线路的通信，然后相应地调整 C++ 或 Java 端。