qt的TCp的disconnect

在Qt中，可以使用QTcpSocket类来连接到TCP服务器。当连接成功建立时，可以通过调用disconnectFromHost()函数来断开与服务器的连接。该函数会关闭套接字并发出disconnected()信号，表示成功断开连接。以下是一个示例：

// 创建一个QTcpSocket对象
QTcpSocket *socket = new QTcpSocket(this);

// 连接到服务器
socket->connectToHost("127.0.0.1", 1234);

// 断开连接
socket->disconnectFromHost();

请注意，断开连接的过程是异步的，并且可能需要一些时间才能完成。因此，建议在调用disconnectFromHost()函数后等待disconnected()信号，以确保连接已经成功断开。

相关问题

QT tcpmodbus 使用示例

好的，我会为您查找 QT tcpmodbus 使用示例。以下是一个基于QT的TCP Modbus主从模拟器，您可以参考：

1. 首先，在QT中创建一个新的工程，选择 QT GUI应用程序类型

2. 在工程目录中创建一个新的文件夹，例如“tcpmodbus”

3. 创建以下文件：

- tcpmodbus.pro
- main.cpp
- modbusconfig.h
- modbusconfig.cpp
- modbusmaster.h
- modbusmaster.cpp
- modbusslave.h
- modbusslave.cpp

4. 打开 tcpmodbus.pro 文件，添加以下内容：

QT += widgets network
HEADERS += modbusconfig.h \
           modbusmaster.h \
           modbusslave.h
SOURCES += main.cpp \
           modbusconfig.cpp \
           modbusmaster.cpp \
           modbusslave.cpp

5. 在 modbusconfig.h 文件中添加以下内容：

#ifndef MODBUSCONFIG_H
#define MODBUSCONFIG_H

const quint16 ModbusPort = 502;
const quint8 ModbusSlaveAddress = 1;

#endif // MODBUSCONFIG_H

6. 在 modbusmaster.h 文件中添加以下内容:

#ifndef MODBUSMASTER_H
#define MODBUSMASTER_H

#include <QObject>
#include <QTcpSocket>

class ModbusMaster : public QObject
{
    Q_OBJECT

public:
    explicit ModbusMaster(QObject *parent = nullptr);

private slots:
    void onConnected();
    void onDisconnected();
    void onError(QAbstractSocket::SocketError socketError);
    void onReadyRead();

private:
    void connectToServer();
    void sendRequest();

    QTcpSocket *tcpSocket;
    QByteArray request;
    QByteArray response;
    int transactionId;
};

#endif // MODBUSMASTER_H

7. 在 modbusmaster.cpp 文件中添加以下内容：

#include "modbusmaster.h"
#include "modbusconfig.h"

ModbusMaster::ModbusMaster(QObject *parent) : QObject(parent)
{
    connectToServer();
}

void ModbusMaster::onConnected()
{
    qDebug() << "Connected to server";

    // Send Modbus request
    sendRequest();
}

void ModbusMaster::onDisconnected()
{
    qDebug() << "Disconnected from server";
}

void ModbusMaster::onError(QAbstractSocket::SocketError socketError)
{
    qDebug() << "Error: " << tcpSocket->errorString();
}

void ModbusMaster::onReadyRead()
{
    // Read response
    response = tcpSocket->readAll();
    qDebug() << "Modbus response: " << response.toHex();

    // Disconnect from server
    tcpSocket->disconnectFromHost();
}

void ModbusMaster::connectToServer()
{
    // Initialize transaction Id
    transactionId = 0;

    // Create socket
    tcpSocket = new QTcpSocket(this);

    // Connect signals and slots
    connect(tcpSocket, &QTcpSocket::connected, this, &ModbusMaster::onConnected);
    connect(tcpSocket, &QTcpSocket::disconnected, this, &ModbusMaster::onDisconnected);
    connect(tcpSocket, static_cast<void(QAbstractSocket::*)(QAbstractSocket::SocketError)>(&QAbstractSocket::error),
            this, &ModbusMaster::onError);
    connect(tcpSocket, &QTcpSocket::readyRead, this, &ModbusMaster::onReadyRead);

    // Connect to server
    tcpSocket->connectToHost("127.0.0.1", ModbusPort);
}

void ModbusMaster::sendRequest()
{
    // Build Modbus request
    transactionId++;

    request.clear();
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x06);
    request.append(ModbusSlaveAddress);
    request.append(0x01);
    request.append(0x00);
    request.append(0x00);
    request.append(0x00);
    request.append(0x01);

    // Send request
    tcpSocket->write(request);
}

8. 在 modbusslave.h 文件中添加以下内容：

#ifndef MODBUSSLAVE_H
#define MODBUSSLAVE_H

#include <QObject>
#include <QTcpServer>
#include <QTcpSocket>

class ModbusSlave : public QObject
{
    Q_OBJECT

public:
    explicit ModbusSlave(QObject *parent = nullptr);

private slots:
    void onNewConnection();
    void onDisconnected();
    void onError(QAbstractSocket::SocketError socketError);
    void onReadyRead();

private:
    void sendResponse(const QByteArray& request);

    QTcpServer *tcpServer;
    QList<QTcpSocket*> sockets;
};

#endif // MODBUSSLAVE_H

9. 在 modbusslave.cpp 文件中添加以下内容：

#include "modbusslave.h"
#include "modbusconfig.h"

ModbusSlave::ModbusSlave(QObject *parent) : QObject(parent)
{
    // Create server
    tcpServer = new QTcpServer(this);

    // Connect signals and slots
    connect(tcpServer, &QTcpServer::newConnection, this, &ModbusSlave::onNewConnection);

    // Listen for incoming connections
    tcpServer->listen(QHostAddress::Any, ModbusPort);
    qDebug() << "Modbus slave listening on port " << tcpServer->serverPort();
}

void ModbusSlave::onNewConnection()
{
    // Accept incoming connection
    QTcpSocket *socket = tcpServer->nextPendingConnection();

    // Connect signals and slots
    connect(socket, &QTcpSocket::disconnected, this, &ModbusSlave::onDisconnected);
    connect(socket, static_cast<void(QAbstractSocket::*)(QAbstractSocket::SocketError)>(&QAbstractSocket::error),
            this, &ModbusSlave::onError);
    connect(socket, &QTcpSocket::readyRead, this, &ModbusSlave::onReadyRead);

    // Add socket to list
    sockets.append(socket);

    qDebug() << "New Modbus connection established";
}

void ModbusSlave::onDisconnected()
{
    // Remove socket from list
    QTcpSocket *socket = static_cast<QTcpSocket*>(sender());
    sockets.removeOne(socket);

    qDebug() << "Modbus connection disconnected";
}

void ModbusSlave::onError(QAbstractSocket::SocketError socketError)
{
    qDebug() << "Error: " << static_cast<QTcpSocket*>(sender())->errorString();
}

void ModbusSlave::onReadyRead()
{
    // Get request
    QTcpSocket *socket = static_cast<QTcpSocket*>(sender());
    QByteArray request = socket->readAll();
    qDebug() << "Modbus request: " << request.toHex();

    // Send response
    sendResponse(request);
}

void ModbusSlave::sendResponse(const QByteArray& request)
{
    QByteArray response;

    // Check slave address
    if (request.at(6) != ModbusSlaveAddress) {
        qDebug() << "Error: wrong slave address";
        return;
    }

    // Check function code
    if (request.at(7) != 0x01) {
        qDebug() << "Error: wrong function code";
        return;
    }

    // Build response
    response.append(request.at(0)); // Transaction Id
    response.append(request.at(1)); // Transaction Id
    response.append(request.at(2)); // Protocol Id
    response.append(request.at(3)); // Protocol Id
    response.append(0x00); // Message length
    response.append(0x06); // Message length
    response.append(ModbusSlaveAddress); // Slave address
    response.append(0x01); // Function code
    response.append(0x01); // Byte count
    response.append(0x00); // Value
    response.append(0x01); // Value

    // Send response to all sockets
    for (QTcpSocket *socket : sockets) {
        socket->write(response);
    }

    qDebug() << "Modbus response: " << response.toHex();
}

10. 在 main.cpp 文件中添加以下内容：

#include <QCoreApplication>
#include "modbusmaster.h"
#include "modbusslave.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // Start Modbus slave
    ModbusSlave modbusSlave;

    // Start Modbus master after 1 second delay
    QTimer::singleShot(1000, [&]() {
        ModbusMaster modbusMaster;
    });

    return a.exec();
}

11. 编译和执行程序。

12. 打开新的QT控制台，输入以下命令来查看 TCP Modbus 数据：

tcpdump -i lo -A port 502

注意：此示例仅用于演示目的，应根据实际要求进行修改和优化，例如加密和身份验证。

QT实现TCP通讯代码

### 回答1：
好的，下面是在 Qt 中实现 TCP 通讯的一些示例代码：

1. 建立一个简单的 TCP 服务器：

#include <QTcpServer>
#include <QTcpSocket>
#include <QDebug>

int main(int argc, char *argv[])
{
    QTcpServer server;
    if (!server.listen(QHostAddress::Any, 1234)) {
        qDebug() << "Failed to start the server";
        return -1;
    }

    qDebug() << "Server is running on port" << server.serverPort();

    while (true) {
        if (server.waitForNewConnection(-1)) {
            QTcpSocket *client = server.nextPendingConnection();
            qDebug() << "New client connected:" << client->peerAddress().toString();

            while (client->waitForReadyRead(-1)) {
                QByteArray data = client->readAll();
                qDebug() << "Received data:" << data;

                client->write(data);
            }

            qDebug() << "Client disconnected:" << client->peerAddress().toString();
            delete client;
        }
    }

    return 0;
}

2. 建立一个简单的 TCP 客户端：

#include <QTcpSocket>
#include <QDebug>

int main(int argc, char *argv[])
{
    QTcpSocket socket;
    socket.connectToHost("127.0.0.1", 1234);
    if (!socket.waitForConnected(-1)) {
        qDebug() << "Failed to connect to the server";
        return -1;
    }

    qDebug() << "Connected to the server";

    socket.write("Hello, server!");
    if (!socket.waitForBytesWritten(-1)) {
        qDebug() << "Failed to write to the server";
        return -1;
    }

    qDebug() << "Data written to the server";

    if (!socket.waitForReadyRead(-1)) {
        qDebug() << "Failed to read from the server";
        return -1;
    }

    qDebug() << "Received data:" << socket.readAll();

    socket.disconnectFromHost();
    if (!socket.waitForDisconnected(-1)) {
        qDebug() << "Failed to disconnect from the server";
        return -1;
    }

    qDebug() << "Disconnected from the server";

    return 0;
}

这些代码是极其简单的示例，仅供参考。在实际应用中，你需要处理更多的细节，如错误处理、断开

### 回答2：
QT是一款广泛使用的跨平台应用开发框架，通过其丰富的库函数和简洁的API，我们可以轻松实现TCP通讯功能。

首先，在QT中，我们可以使用QTcpSocket类来创建一个客户端或服务器端的套接字，以实现与远程主机的TCP连接。我们可以使用QTcpSocket的connectToHost函数来连接到服务器，或者使用listen函数来监听指定的端口。

一旦连接建立，我们可以使用QTcpSocket的write函数向服务器发送数据，使用readyRead信号和read函数来接收服务器发送的数据。同时，也可以使用connected和disconnected信号来处理与服务器的连接状态变化。

下面是一个简单的示例代码，演示了如何使用QT实现TCP通讯：

#include <QtNetwork>

QTcpSocket *tcpSocket;

void connectToServer()
{
    tcpSocket = new QTcpSocket(this);
    
    connect(tcpSocket, &QTcpSocket::connected, this, &Client::connected);
    connect(tcpSocket, &QTcpSocket::disconnected, this, &Client::disconnected);
    connect(tcpSocket, &QTcpSocket::readyRead, this, &Client::readyRead);
    
    tcpSocket->connectToHost("localhost", 1234); // 连接到服务器的IP地址和端口号
    
    if(tcpSocket->waitForConnected(3000)){
        qDebug() << "Connected to server";
        
        tcpSocket->write("Hello, server"); // 向服务器发送数据
    }else{
        qDebug() << "Failed to connect to server";
    }
}

void Client::connected()
{
    qDebug() << "Connected to server";
}

void Client::disconnected()
{
    qDebug() << "Disconnected from server";
}

void Client::readyRead()
{
    QByteArray data = tcpSocket->readAll();
    
    qDebug() << "Received data:" << data;
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    
    connectToServer();
    
    return a.exec();
}

在这个例子中，我们首先创建了一个QTcpSocket对象tcpSocket，并通过connect函数将其connected、disconnected和readyRead信号与相应的槽函数连接起来。接着，我们调用tcpSocket的connectToHost函数连接到指定的服务器。成功连接后，我们向服务器发送数据，并在readyRead槽函数中接收并打印服务器返回的数据。

通过这样的方式，我们可以轻松使用QT实现TCP通讯功能，并根据具体需求对代码进行扩展和优化。

### 回答3：
import sys
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtNetwork import *

class ClientWindow(QWidget):
def __init__(self):
super().__init__()
self.setWindowTitle("TCP Client")
self.setFixedSize(300, 200)

self.host_label = QLabel("Server Address:")
self.host_input = QLineEdit()
self.port_label = QLabel("Server Port:")
self.port_input = QLineEdit()
self.connect_button = QPushButton("Connect")
self.disconnect_button = QPushButton("Disconnect")
self.send_button = QPushButton("Send")
self.send_input = QLineEdit()
self.receive_output = QTextEdit()
self.receive_output.setReadOnly(True)

self.layout = QVBoxLayout()
self.layout.addWidget(self.host_label)
self.layout.addWidget(self.host_input)
self.layout.addWidget(self.port_label)
self.layout.addWidget(self.port_input)
self.layout.addWidget(self.connect_button)
self.layout.addWidget(self.disconnect_button)
self.layout.addWidget(self.send_input)
self.layout.addWidget(self.send_button)
self.layout.addWidget(self.receive_output)
self.setLayout(self.layout)

self.tcp_socket = None

self.connect_button.clicked.connect(self.connect_to_server)
self.disconnect_button.clicked.connect(self.disconnect_from_server)
self.send_button.clicked.connect(self.send_data)

def connect_to_server(self):
host = self.host_input.text()
port = int(self.port_input.text())
self.tcp_socket = QTcpSocket()
self.tcp_socket.readyRead.connect(self.receive_data)
self.tcp_socket.error.connect(self.display_error)

self.tcp_socket.connectToHost(host, port)
if self.tcp_socket.waitForConnected(1000):
self.receive_output.append("Connected to the server.")

def disconnect_from_server(self):
self.tcp_socket.disconnectFromHost()
self.tcp_socket.deleteLater()
self.tcp_socket = None
self.receive_output.append("Disconnected from the server.")

def send_data(self):
if self.tcp_socket is not None:
data = self.send_input.text()
data = data.encode()
self.tcp_socket.write(data)
self.send_input.clear()

def receive_data(self):
if self.tcp_socket is not None:
while self.tcp_socket.bytesAvailable() > 0:
data = self.tcp_socket.readAll()
self.receive_output.append("Received: " + str(data, 'utf-8'))

def display_error(self, socket_error):
self.receive_output.append("Error: " + self.tcp_socket.errorString())

if __name__ == "__main__":
app = QApplication(sys.argv)
window = ClientWindow()
window.show()
sys.exit(app.exec_())