97 TCP客户机功能实现

第三步，实现TcpClient的通信功能。

97.1 实现功能

C:\Users\Minwei\Projects\Qt\TcpClient\tcpclientwindow.h：

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#ifndef TCPCLIENTWINDOW_H
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#define TCPCLIENTWINDOW_H
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#include <QMainWindow>
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#include <QLabel>
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#include <QTcpSocket>
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QT_BEGIN_NAMESPACE
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namespace Ui { class TcpClientWindow; }
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QT_END_NAMESPACE
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class TcpClientWindow : public QMainWindow
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{
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    Q_OBJECT
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public:
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    TcpClientWindow(QWidget *parent = nullptr);
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    ~TcpClientWindow();
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private slots:
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    void on_m_actConnect_triggered();
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    void on_m_actDisconnect_triggered();
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    void on_m_actClear_triggered();
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    void on_m_btnSend_clicked();
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    void on_m_socket_connected();
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    void on_m_socket_readyRead();
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    void on_m_socket_disconnected();
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    void on_m_socket_stateChanged(
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        QAbstractSocket::SocketState socketState);
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    void on_m_socket_error(
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        QAbstractSocket::SocketError socketError);
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private:
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    Ui::TcpClientWindow *ui;
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    QLabel* m_labConnectionState;
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    QLabel* m_labSocketState;
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    QLabel* m_labSocketError;
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    QTcpSocket* m_socket;
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};
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#endif // TCPCLIENTWINDOW_H

C:\Users\Minwei\Projects\Qt\TcpClient\tcpclientwindow.cpp：

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#include <QHostInfo>
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#include <QMetaEnum>
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#include "tcpclientwindow.h"
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#include "ui_tcpclientwindow.h"
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TcpClientWindow::TcpClientWindow(QWidget *parent)
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    : QMainWindow(parent)
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    , ui(new Ui::TcpClientWindow)
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    , m_labConnectionState(new QLabel("连接状态：断开"))
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    , m_labSocketState(new QLabel(" 套接字状态："))
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    , m_labSocketError(new QLabel(" 套接字错误："))
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    , m_socket(new QTcpSocket(this))
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{
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    ui->setupUi(this);
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    m_labConnectionState->setMinimumWidth(196);
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    ui->m_statusBar->addWidget(m_labConnectionState);
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    m_labSocketState->setMinimumWidth(197);
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    ui->m_statusBar->addWidget(m_labSocketState);
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    m_labSocketError->setMinimumWidth(197);
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    ui->m_statusBar->addWidget(m_labSocketError);
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    connect(m_socket, SIGNAL(connected()),
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        this, SLOT(on_m_socket_connected()));
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    connect(m_socket, SIGNAL(readyRead()),
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        this, SLOT(on_m_socket_readyRead()));
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    connect(m_socket, SIGNAL(disconnected()),
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        this, SLOT(on_m_socket_disconnected()));
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    connect(m_socket, SIGNAL(stateChanged(QAbstractSocket::SocketState)),
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        this, SLOT(on_m_socket_stateChanged(QAbstractSocket::SocketState)));
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    connect(m_socket, SIGNAL(error(QAbstractSocket::SocketError)),
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        this, SLOT(on_m_socket_error(QAbstractSocket::SocketError)));
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}
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TcpClientWindow::~TcpClientWindow()
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{
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    delete ui;
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}
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void TcpClientWindow::on_m_actConnect_triggered()
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{
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    m_socket->connectToHost(ui->m_editRemoteAddr->text(),
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        ui->m_editRemotePort->text().toUShort());
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}
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void TcpClientWindow::on_m_actDisconnect_triggered()
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{
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    m_socket->disconnectFromHost();
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}
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void TcpClientWindow::on_m_actClear_triggered()
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{
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    ui->m_editOutput->clear();
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}
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void TcpClientWindow::on_m_btnSend_clicked()
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{
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    QByteArray data((ui->m_editSend->text() + "\n").toUtf8());
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    qint64 nbytes = m_socket->write(data);
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    if (nbytes == -1)
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        ui->m_editOutput->appendPlainText("发送失败");
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    else
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        ui->m_editOutput->appendPlainText(QString("向%1:%2发送%3字节：%4").
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            arg(m_socket->peerAddress().toString()).arg(m_socket->peerPort()).
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            arg(nbytes).arg(QString(data).trimmed()));
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}
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void TcpClientWindow::on_m_socket_connected()
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{
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    ui->m_editOutput->appendPlainText(QString("建立%1:%2连接").
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        arg(m_socket->peerAddress().toString()).arg(m_socket->peerPort()));
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    m_labConnectionState->setText(QString("连接状态：%1:%2").
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        arg(m_socket->peerAddress().toString()).arg(m_socket->peerPort()));
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    ui->m_btnSend->setEnabled(true);
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}
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void TcpClientWindow::on_m_socket_readyRead()
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{
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    while (m_socket->canReadLine())
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    {
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        QByteArray data = m_socket->readLine();
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        ui->m_editOutput->appendPlainText(QString("从%1:%2接收%3字节：%4").
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            arg(m_socket->peerAddress().toString()).arg(m_socket->peerPort()).
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            arg(data.size()).arg(QString(data).trimmed()));
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    }
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}
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void TcpClientWindow::on_m_socket_disconnected()
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{
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    ui->m_btnSend->setEnabled(false);
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    ui->m_editOutput->appendPlainText(QString("断开%1:%2连接").
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        arg(m_socket->peerAddress().toString()).arg(m_socket->peerPort()));
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    m_labConnectionState->setText("连接状态：断开");
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}
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void TcpClientWindow::on_m_socket_stateChanged(
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    QAbstractSocket::SocketState socketState)
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{
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    m_labSocketState->setText(QString(" 套接字状态：%1").arg(
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        QMetaEnum::fromType<QAbstractSocket::SocketState>().
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        valueToKey(socketState)));
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}
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void TcpClientWindow::on_m_socket_error(
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    QAbstractSocket::SocketError socketError)
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{
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    m_labSocketError->setText(QString(" 套接字错误：%1").arg(
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        QMetaEnum::fromType<QAbstractSocket::SocketError>().
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        valueToKey(socketError)));
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}

97.2 测试验证

运行效果如图所示：