如何将Qt编程实现一个支持长尾词查询的TCP客户端与服务器端通讯程序？

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复习的心态要过一遍基础内容，Qt封装了QTcpServer和QTcpSocket两个类，QTcpServer继承自QObject，通过listen()函数监听客户端连接。当客户端连接时，QTcpServer会触发newConnection信号。

复习的心态过一遍之前基础的一些东西，Qt封装了QTcpServer和QTcpSocket两个类，其中QTcpServer继承自QObject，通过listen()函数监听传入的客户端连接，当Client连接上时，QTcpServer会发出newConnection的信号，在对应的槽函数中使用nextPendingConnection()拿到连接的客户端的句柄和信息。

而QTcpSocket则是读写数据的时候使用，过程很简单。

服务器流程：listen->newConnection->nextPendingConnection->readAll/write

客户端流程：connectToHost->waitForConnected->write/readAll

需要注意的是在使用网络相关的类前，需要在pro文件加上QT += network

通信时：

客户端掉线时：

QTcpServer服务器代码（包含.h和.cpp）:

.h

#ifndef WIDGET_H #define WIDGET_H   #include <QWidget> #include <QTcpServer> #include <QTcpSocket>   QT_BEGIN_NAMESPACE namespace Ui { class Widget; } QT_END_NAMESPACE   class Widget : public QWidget {     Q_OBJECT   public:     Widget(QWidget *parent = nullptr);     ~Widget();   protected slots:     void onSendBtnClicked();     void onNewClientConnected();     void onRecvData();     void onClientDisconnected();   private:     void Init();   private:     Ui::Widget *ui;   private:     QTcpServer *_tcpServer;     QTcpSocket *_tcpSocket; }; #endif // WIDGET_H

.cpp

#include "widget.h" #include "ui_widget.h" #include <QHostAddress> #include <QDebug>   #define MyTcpPort 8886   Widget::Widget(QWidget *parent)     : QWidget(parent)     , ui(new Ui::Widget)     ,_tcpServer(nullptr)     ,_tcpSocket(nullptr) {     ui->setupUi(this);       connect(this->ui->btn_send,&QPushButton::clicked,this,&Widget::onSendBtnClicked);       Init();       setWindowTitle("服务端"); }   Widget::~Widget() {     delete ui;       if(_tcpSocket)     {         _tcpSocket->disconnect();         _tcpSocket->abort();         _tcpSocket->close();         _tcpSocket->deleteLater();     }     if(_tcpServer)     {         _tcpServer->close();         delete _tcpServer;     } }   void Widget::Init() {     _tcpSocket = new QTcpSocket;     _tcpServer = new QTcpServer;       int ret = _tcpServer->listen(QHostAddress::AnyIPv4,MyTcpPort);     if(ret==0)     {         qDebug()<<"_tcpServer->listen is failied";         return;     }     connect(_tcpServer,&QTcpServer::newConnection,this,&Widget::onNewClientConnected); }   void Widget::onSendBtnClicked() {     if(!_tcpSocket) return;       QString inputText = ui->inputEdit->text();     if(inputText.isEmpty())         return;     //发送数据     int ret = _tcpSocket->write(inputText.toStdString().c_str());     if(ret<0)     {         qDebug()<<"write to client is failed!";     } }   void Widget::onNewClientConnected() {     if(_tcpServer->hasPendingConnections())     {         _tcpSocket = _tcpServer->nextPendingConnection();         if(!_tcpSocket->isValid()) return;         connect(_tcpSocket,&QTcpSocket::readyRead,this,                 &Widget::onRecvData);         connect(_tcpSocket,&QTcpSocket::disconnected,this,                 &Widget::onClientDisconnected);     } }   void Widget::onRecvData() {     if(!_tcpSocket) return;     QString recvData=_tcpSocket->readAll();     qDebug()<<"recvData:"<<recvData;       this->ui->recvEdit->append(recvData); }   void Widget::onClientDisconnected() {     QString clientIp = _tcpSocket->peerAddress().toString();     this->ui->recvEdit->append(clientIp+" is Drop line!"); }

QTcpClient客户端代码（包含.h和.cpp）:

/.h

#ifndef WIDGET_H #define WIDGET_H   #include <QWidget> #include <QTcpSocket>   QT_BEGIN_NAMESPACE namespace Ui { class Widget; } QT_END_NAMESPACE   class Widget : public QWidget {     Q_OBJECT   public:     Widget(QWidget *parent = nullptr);     ~Widget();   private:     void Init();   protected slots:     void onSendBtnClicked();     void onRecvData();   private:     Ui::Widget *ui;   private:     QTcpSocket *_tcpClient; }; #endif // WIDGET_H   /.cpp #include "widget.h" #include "ui_widget.h"   #define MyTcpPort 8886   Widget::Widget(QWidget *parent)     : QWidget(parent)     , ui(new Ui::Widget),_tcpClient(nullptr) {     ui->setupUi(this);       connect(this->ui->btn_send,&QPushButton::clicked,this,&Widget::onSendBtnClicked);       Init();        setWindowTitle("客户端"); }   Widget::~Widget() {     delete ui;       if(_tcpClient)     {         _tcpClient->close();         _tcpClient->deleteLater();     } }   void Widget::Init() {     _tcpClient=new QTcpSocket;     _tcpClient->abort();     _tcpClient->connectToHost("127.0.0.1",MyTcpPort);     if(!_tcpClient->waitForConnected(2000))     {         qDebug()<<"connect is failed!";         return;     }     qDebug()<<"connect is successful";     connect(_tcpClient,&QTcpSocket::readyRead,this,&Widget::onRecvData); }   void Widget::onSendBtnClicked() {     if(!_tcpClient) return;       QString wStr=ui->inputEdit->text();       int ret = _tcpClient->write(wStr.toStdString().c_str());     if(ret<0)     {         qDebug()<<"send data is failed";     }     qDebug()<<"send data is successful!"; }   void Widget::onRecvData() {     if(!_tcpClient) return;       QString recvData= _tcpClient->readAll();     ui->recvEdit->append(recvData);     qDebug()<<"recvData:"<<recvData; }

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