QTcpServer类 用来侦听端口 ，获取QTcpSocket.

QTcpSocket有  connected的信号（已经连接）,还有readyread()信号，表示已经有数据发过来了，准备读取。

  若要关闭 当前连接只需要 调用 qtcpsocket::close();就关闭了当前连接

下面有两个例子

   服务器端

用的是控制台程序（QT） 当用户 发送数据过来 就cout显示，然后就write一个 I Love You的字符串 返回到客户端。然后close断开连接

客户端

  用的书图形界面，一个输入框 输入数据 然后发送，最后 QMessagebox显示服务器返回消息

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服务器端(三个文件)

#ifndef MYSERVER_H#define MYSERVER_H#include
    
     #include
     
      #include 
      
       #include
       
        class myserver : public QTcpServer{    Q_OBJECTpublic:    QTcpSocket * socket;    QTcpServer *server;    myserver();private slots:    void getData();    void newconnectslot();};#endif // MYSERVER_H#include "myserver.h"#include
        
         #include
         
          #include
          
           myserver::myserver(){    this->socket=new QTcpSocket;    this->server=new QTcpServer;    if(this->server->listen(QHostAddress::Any,520))    {        std::cout<<"bind port 520 successful."<
           
            server,SIGNAL(newConnection()),this,SLOT(newconnectslot()));}void myserver::newconnectslot(){    this->socket=this->server->nextPendingConnection();    connect(this->socket,SIGNAL(readyRead()),this,SLOT(getData()));}void myserver::getData(){    QByteArray by=this->socket->readAll();    QDataStream ds(by);    QString x;    ds>>x;    QByteArray ba = x.toLatin1();    char * p=ba.data();    std::cout<
            
<
             
              write("I love you");//返回给客户端    this->socket->close();//断开连接}#include 
              
               #include
               
                #include"myserver.h"#include
                
                 int main(int argc, char *argv[]){    QCoreApplication a(argc, argv);    std::cout<<"--Server initialized By HanHan--"<
                
               
              
             
           
          
         
        
       
      
     
    

客户端（三个文件）

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include 
    
     #include
     
      #include
      
       #include
       
        #include
        
         namespace Ui {class MainWindow;}class MainWindow : public QMainWindow{    Q_OBJECTpublic:    QTcpSocket * socket;    explicit MainWindow(QWidget *parent = 0);    ~MainWindow();private slots:    void connnectslot();    void on_btn_send_clicked();    void readyslot();private:    Ui::MainWindow *ui;};#endif // MAINWINDOW_H
        
       
      
     
    

#include "mainwindow.h"#include "ui_mainwindow.h"#include
    
     #include
     
      MainWindow::MainWindow(QWidget *parent) :    QMainWindow(parent),    ui(new Ui::MainWindow){    ui->setupUi(this);    this->socket=new QTcpSocket;}MainWindow::~MainWindow(){    delete ui;}void MainWindow::on_btn_send_clicked(){    QHostAddress address("127.0.0.1");    this->socket->connectToHost(address,520);    connect(this->socket,SIGNAL(connected()),this,SLOT(connnectslot()));    connect(this->socket,SIGNAL(readyRead()),this,SLOT(readyslot()));//接收发来的数据}void MainWindow::connnectslot(){     QString data=this->ui->data_edit->toPlainText();     QByteArray array;     QDataStream ds(&array,QIODevice::WriteOnly);     ds<
      
       socket->write(array);}
      
     
    

void MainWindow::readyslot(){    QString x=this->socket->readAll();    QMessageBox::about(this,"x",x);}#include "mainwindow.h"#include 
    

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

运行截图：

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