亲宝软件园·资讯

展开

Qt TCP网络通信

skynetkang 人气:0

TCP简介:

Transmission Control Protocol,传输控制协议 。用于数据传输的低层网络协议,多个物联网协议都是基于TCP协议的。它是一个面向数据流和连接的可靠传输协议。

TCP头部格式:

QTcpSocket类为TCP提供了一个接口,继承自QAbstractSocket。可实现POP3、SMTP、NNTP等标准的网络协议,也可以实现自定义的网络协议。异步工作,依靠事件循环来检测到来的数据,并且自动刷新输出的数据。而QAbstractSocket继承自QIODevice,故该类具备文件的读写功能,可以使用QTextStream和QDataStream。

QHostAddress QAbstractSocket::peerAddress () const  获取主机的IP地址

quint16 QAbstractSocket::peerPort () const  获取主机的端口号

qint64 QIODevice::write ( const QByteArray & byteArray )  //写入数据,即通过TCP发送数据。

QByteArray QIODevice::read ( qint64 maxSize )   //读取数据,最多读取maxSize。即获取TCP接收的存放在缓冲区的数据

QByteArray QIODevice::readAll ()  //获取TCP存放在缓冲区可读取的所有数据。

从一个QTcpSocket中读取数据前,必须先调用qint64 QIODevice::bytesAvailable () const 函数来确保已经有足够的数据可用。

涉及到的信号:

void QAbstractSocket::connected () [signal]  当连接建立成功发射连接信号,指示一个已建立的新连接。

void QAbstractSocket::error ( QAbstractSocket::SocketError socketError ) [signal]  连接发生了错误,就会发送error()信号,参数指示发生了什么错误。

void QAbstractSocket::disconnected () [signal]  断开一个已经存在的连接时,发射断开信号。

void QAbstractSocket::stateChanged ( QAbstractSocket::SocketState socketState ) [signal]  状态改变都会发射stateChanged()信号。

void QIODevice::bytesWritten ( qint64 bytes ) [signal]  表示数据写入完成,对应的可以调用bytesToWrite()方法了解写入了多少字节的数据。

void QIODevice::readyRead () [signal]  表示有数据可以读取,对应的可以调用bytesAvailable()方法了解可以读取多少字节的数据。

一个简单的TCP客户端和服务端程序,单连接。

客户端程序:

#ifndef QTTCPCLIENT_H
#define QTTCPCLIENT_H
 
#include <QObject>
#include <QAbstractSocket>
 
class QTcpSocket; //前置声明
 
//客户端程序  单连接,即一个客户端一个服务端
class QtTcpClient : public QObject
{
    Q_OBJECT
public:
    explicit QtTcpClient(QObject *parent = 0);
    ~QtTcpClient();
 
    void sendMessage(); //发送信息
 
private slots:
    void readMessage();  //获取返回的信息
    void displayError(QAbstractSocket::SocketError);  //获取连接发生的错误
 
 
private:
 
    QTcpSocket *tcpSocket;  //tcp连接
 
    quint16 blockSize;  //发送数据的大小
};
 
#endif // QTTCPCLIENT_H

#include "qttcpclient.h"
#include <QtNetwork>
#include <QDataStream>
#include <QString>
#include <QByteArray>
#include <QIODevice>
#include <QObject>
#include <QDebug>
 
QtTcpClient::QtTcpClient(QObject *parent) :
    QObject(parent)
{
    tcpSocket=new QTcpSocket(this);
    //建立信号连接,readyRead表示有数据过来,需要读取
    connect(tcpSocket,SIGNAL(readyRead()),this,SLOT(readMessage()));
    //建立信号连接,error(QAbstractSocket::SocketError)连接发生错误或关闭时会发射此信号
    connect(tcpSocket,SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(displayError(QAbstractSocket::SocketError)));
 
    blockSize=0;
    tcpSocket->abort();//终止已有的连接
 
    tcpSocket->connectToHost(QHostAddress(QString("127.0.0.1")),6666);//建立新的连接
 
    qDebug()<<"client run......"<<endl;
}
 
QtTcpClient::~QtTcpClient()
{
    delete tcpSocket;
    tcpSocket=NULL;
}
 
void QtTcpClient::sendMessage()
{
    QByteArray block;
    QDataStream out(&block,QIODevice::WriteOnly);
 
    out.setVersion(QDataStream::Qt_4_0);
    out<<(quint16)0;
    out<<QString("hi server this is my first connect!!!");
    out.device()->seek(0);//定位到数据的开头
    out<<(quint16)(block.size()-sizeof(quint16)); //添加数据大小信息到数据开头
 
    tcpSocket->write(block); //发送数据
 
}
 
void QtTcpClient::readMessage()
{
    QString message;
    QDataStream in(tcpSocket);
    in.setVersion(QDataStream::Qt_4_0);
 
    if(blockSize==0)
    {
        //判断接收的数据是否大于两字节,也就是文件的大小信息所占的空间
        //如果是则保存到blockSize中,否则直接返回,继续接收数据。
        if(tcpSocket->bytesAvailable()<(int)sizeof(quint16))
        {
            return;
        }
 
        in>>blockSize;
    }
    //如果没有接收完全部数据,则返回继续接收
    if(tcpSocket->bytesAvailable()<blockSize)
    {
        return;
    }
    //将接收的数据存放到变量中
    in>>message;
 
    qDebug()<<message;
 
    this->sendMessage();
 
    //断开连接
    tcpSocket->disconnectFromHost();
}
 
void QtTcpClient::displayError(QAbstractSocket::SocketError)
{
    switch(tcpSocket->error())
    {
    case QAbstractSocket::RemoteHostClosedError:  //远程服务端关闭连接错误
        tcpSocket->disconnectFromHost();
        qDebug()<<"client close now";
        break;
    default:
        qDebug()<<"error id: "<<tcpSocket->error()<<endl;
        qDebug()<<"error message: "<<tcpSocket->errorString()<<endl;
        break;
    }
}

 
#include <QCoreApplication>
#include "qttcpclient.h"
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QtTcpClient tcpclient_t;
    
    return a.exec();
}

服务端程序:

#ifndef QTTCPSERVER_H
#define QTTCPSERVER_H
 
#include <QObject>
#include <QAbstractSocket>
 
class QTcpServer; //前置声明
class QTcpSocket;
 
//服务端程序  单连接,即一个客户端一个服务端
class QtTcpServer : public QObject
{
    Q_OBJECT
public:
    explicit QtTcpServer(QObject *parent = 0);
    ~QtTcpServer();
 
private slots:
    void sendMessage();//发送信息
    void readMessage();//获取返回的信息
    void displayError(QAbstractSocket::SocketError);//获取连接发生的错误
 
private:
    QTcpServer *tcpServer; //tcp服务端
 
    QTcpSocket *clientConnect;//来自客户端的连接
    quint16 blockSize;  //接收数据的大小
};
 
#endif // QTTCPSERVER_H
 
 
#include "qttcpserver.h"
#include <QtNetwork>
#include <QDataStream>
#include <QString>
#include <QByteArray>
#include <QIODevice>
#include <QObject>
#include <QDebug>
 
QtTcpServer::QtTcpServer(QObject *parent) :
    QObject(parent)
{
    blockSize=0;
    tcpServer=new QTcpServer(this);
 
    //开始监听
    if(!tcpServer->listen(QHostAddress(QString("127.0.0.1")),6666))
    {
        qDebug()<<tcpServer->serverError()<<endl;
        qDebug()<<tcpServer->errorString()<<endl;
        qApp->exit();
    }
    //建立信号连接,每来一个新的连接,就发送服务端信息
    connect(tcpServer,SIGNAL(newConnection()),this,SLOT(sendMessage()));
 
    qDebug()<<"server run....."<<endl;
}
 
QtTcpServer::~QtTcpServer()
{
    delete tcpServer;
    tcpServer=NULL;
 
    delete clientConnect;
    clientConnect=NULL;
}
 
void QtTcpServer::sendMessage()
{
    QByteArray block;
    QDataStream out(&block,QIODevice::WriteOnly);
 
    out.setVersion(QDataStream::Qt_4_0);
    out<<(quint16)0;
    out<<QString("hello client the connect build!!!");
    out.device()->seek(0);
    out<<(quint16)(block.size()-sizeof(quint16));
 
    clientConnect=tcpServer->nextPendingConnection();//获取客户端的连接
    tcpServer->close();
 
    //关联套接字的disconnected()和deleteLater(),表明当连接断开时删除该套接字
    connect(clientConnect,SIGNAL(disconnected()),clientConnect,SLOT(deleteLater()));
 
    clientConnect->write(block);
 
    connect(clientConnect,SIGNAL(readyRead()),this,SLOT(readMessage()));
    connect(clientConnect,SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(displayError(QAbstractSocket::SocketError)));
 
}
 
void QtTcpServer::readMessage()
{
    QString message;
    QDataStream in(clientConnect);
    in.setVersion(QDataStream::Qt_4_0);
 
    if(blockSize==0)
    {
        if(clientConnect->bytesAvailable()<(int)sizeof(quint16))
        {
            return;
        }
 
        in>>blockSize;
    }
 
    if(clientConnect->bytesAvailable()<blockSize)
    {
        return;
    }
 
    in>>message;
 
    qDebug()<<message;
 
}
 
void QtTcpServer::displayError(QAbstractSocket::SocketError)
{
    switch(clientConnect->error())
    {
    case QAbstractSocket::RemoteHostClosedError:
        clientConnect->disconnectFromHost(); //disconnectFromHost函数会一直等待套接字将所有数据发送完毕,然后关闭该套接字,并发射disconnected信号
        qDebug()<<"server connect close"<<endl;
        break;
    default:
        qDebug()<<"error id: "<<clientConnect->error()<<endl;
        qDebug()<<"error message: "<<clientConnect->errorString()<<endl;
        clientConnect->disconnectFromHost();
        qDebug()<<"server connect close"<<endl;
        break;
    }
}
 
#include <QCoreApplication>
#include "qttcpserver.h"
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QtTcpServer tcpserver_t;
    
    return a.exec();
}

运行结果:

基于TCP的文件传输程序:

客户端程序:

#ifndef CLIENT_H
#define CLIENT_H
#include <QAbstractSocket>
#include <QDialog>
#include <QFile>
#include <QTcpSocket>
#include <QString>
#include <QByteArray>
 
namespace Ui {
class Client;
}
 
class Client : public QDialog
{
    Q_OBJECT
    
public:
    explicit Client(QWidget *parent = 0);
    ~Client();
 
private slots:
    void openFile();
    void send();
    void startTransfer();
    void updateClientProgress(qint64);
    void displayError(QAbstractSocket::SocketError);
    
    void on_pushButton_open_clicked();
    void on_pushButton_send_clicked();
 
private:
    Ui::Client *ui;
 
    QTcpSocket *tcpClient; //tcp连接
    QFile *localFile;      //要发送的文件
    qint64 totalBytes;     //发送数据的总大小
    qint64 bytesWritten;   //已经发送的数据大小
    qint64 bytesToWrite;   //剩余的数据大小
    qint64 payloadSize;    //每次发送数据的大小
    QString fileName;      //保存文件路径
    QByteArray outBlock;   //数据缓冲区,即存放每次要发送的数据块
};
 
#endif // CLIENT_H
 
 
#include "client.h"
#include "ui_client.h"
#include <QtNetwork>
#include <QFileDialog>
#include <QDebug>
 
Client::Client(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Client)
{
    ui->setupUi(this);
 
    //初始化变量
    this->payloadSize=64*1024;   //64KB,每次发送的数据块大小为64KB
    this->totalBytes=0;
    this->bytesWritten=0;
    this->bytesToWrite=0;
 
    this->tcpClient=new QTcpSocket(this);
 
    //当连接服务器成功时,发送connected()信号,开始传送文件
    connect(this->tcpClient,SIGNAL(connected()),this,SLOT(startTransfer()));
    //每次发送成功后发送bytesWritten(qint64))信号,告诉已成功发送的数据块大小,并更新进度条
    connect(this->tcpClient,SIGNAL(bytesWritten(qint64)),this,SLOT(updateClientProgress(qint64)));
    //接收tcp连接发生的错误
    connect(this->tcpClient,SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(displayError(QAbstractSocket::SocketError)));
 
    ui->pushButton_send->setEnabled(false);
}
 
Client::~Client()
{
    delete ui;
}
 
void Client::openFile()
{
    this->fileName=QFileDialog::getOpenFileName(this);
    if(!this->fileName.isEmpty())
    {
        ui->pushButton_send->setEnabled(true);
        ui->label_state->setText(QString("打开文件 %1 成功").arg(this->fileName));
    }
}
 
void Client::send()
{
    ui->pushButton_send->setEnabled(false);
 
    this->bytesWritten=0;
    ui->label_state->setText(QString("连接中..."));
    //连接服务器
    this->tcpClient->connectToHost(ui->lineEdit_host->text(),ui->lineEdit_port->text().toInt());
}
 
void Client::startTransfer()
{
    this->localFile=new QFile(this->fileName);
    //打开文件
    if(!this->localFile->open(QFile::ReadOnly))
    {
        qDebug()<<"client: open file error!"<<endl;
        return;
    }
 
    //获取打开文件的大小
    this->totalBytes=this->localFile->size();
 
    QDataStream sendOut(&this->outBlock,QIODevice::WriteOnly);
    sendOut.setVersion(QDataStream::Qt_4_0);
    //获取文件名(去掉文件前面的路径)
    QString currentFileName=this->fileName.right(this->fileName.size()-this->fileName.lastIndexOf('/')-1);
    //保留总大小信息空间,文件名大小信息空间,然后输入文件名
    sendOut<<qint64(0)<<qint64(0)<<currentFileName;
    //总大小变量为总大小信息、文件名大小信息、文件名和实际文件大小的总和
    this->totalBytes+=this->outBlock.size();
    //返回outBlock的开始,填入总大小信息
    sendOut.device()->seek(0);
    //填入各个项的大小信息以及文件名
    sendOut<<this->totalBytes<<qint64(this->outBlock.size()-sizeof(qint64)*2);
    //发送完文件头结构后剩余数据的大小
    this->bytesToWrite=this->totalBytes-this->tcpClient->write(this->outBlock);
 
    ui->label_state->setText(QString("已连接"));
    this->outBlock.resize(0);
}
 
void Client::updateClientProgress(qint64 numBytes)
{
    //更新已经发送数据的大小
    this->bytesWritten+=(int)numBytes;
    //如果已经发送了数据
    if(this->bytesToWrite>0)
    {
        //每次发送payloadSize大小的数据,不足就发送剩余数据大小
        this->outBlock=this->localFile->read(qMin(this->bytesToWrite,this->payloadSize));
        //发送完一次数据后还剩余数据的大小
        this->bytesToWrite-=(int)this->tcpClient->write(this->outBlock);
        //清空发送缓冲区
        this->outBlock.resize(0);
    }
    else
    {
        //如果没有发送任何数据,就关闭文件
        this->localFile->close();
    }
 
    //更新进度条
    ui->progressBar->setMaximum(this->totalBytes);
    ui->progressBar->setValue(this->bytesWritten);
 
    //发送完毕
    if(this->bytesWritten==this->totalBytes)
    {
        ui->label_state->setText(QString("传送文件 %1 成功").arg(this->fileName));
        this->localFile->close(); //关闭文件
        this->tcpClient->close(); //关闭tcp连接
    }
}
 
void Client::displayError(QAbstractSocket::SocketError)
{
    qDebug()<<this->tcpClient->errorString()<<endl;
    this->tcpClient->close();
    ui->progressBar->reset();
    ui->label_state->setText(QString("客户端已就绪!"));
    ui->pushButton_send->setEnabled(true);
}
 
void Client::on_pushButton_open_clicked()
{
    ui->progressBar->reset();
    ui->label_state->setText(QString("状态:等待文件打开!"));
    this->openFile();
}
 
void Client::on_pushButton_send_clicked()
{
    this->send();
}
 
 
#include <QApplication>
#include "client.h"
#include <QTextCodec>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QTextCodec::setCodecForCStrings(QTextCodec::codecForLocale());
    QTextCodec::setCodecForLocale(QTextCodec::codecForLocale());
    QTextCodec::setCodecForTr(QTextCodec::codecForLocale());
 
    Client w;
    w.show();
    
    return a.exec();
}

服务器程序:

#ifndef SERVER_H
#define SERVER_H
 
#include <QDialog>
#include <QFile>
#include <QTcpSocket>
#include <QTcpServer>
#include <QAbstractSocket>
#include <QString>
#include <QByteArray>
 
namespace Ui {
class Server;
}
 
class Server : public QDialog
{
    Q_OBJECT
    
public:
    explicit Server(QWidget *parent = 0);
    ~Server();
 
private slots:
    void start();
    void acceptConnection();
    void updateServerProgress();
    void displayError(QAbstractSocket::SocketError socketError);
 
    void on_pushButton_clicked();
 
private:
    Ui::Server *ui;
 
    QTcpServer tcpServer; //服务器监听
    QTcpSocket *tcpServerConnection; //来自客户端的连接
 
    qint64 totalBytes;  //存放总大小信息
    qint64 bytesReceived; //已收到的数据大小
    qint64 fileNameSize; //存放文件名的大小信息
 
    QString fileName;  //存放文件名
    QFile *localFile;  //本地文件
    QByteArray inBlock;  //数据缓冲区
};
 
#endif // SERVER_H
 
#include "server.h"
#include "ui_server.h"
#include <QtNetwork>
#include <QDebug>
 
Server::Server(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Server)
{
    ui->setupUi(this);
    //有新的连接到来,发射newConnection()信号,获取新的连接
    connect(&this->tcpServer,SIGNAL(newConnection()),this,SLOT(acceptConnection()));
}
 
Server::~Server()
{
    delete ui;
}
 
void Server::start()
{
    //建立监听
    if(!this->tcpServer.listen(QHostAddress(QString("127.0.0.1")),6666))
    {
        qDebug()<<this->tcpServer.errorString()<<endl;
        close();
        return;
    }
 
    ui->pushButton->setEnabled(false);
    //初始化变量
    this->totalBytes=0;
    this->bytesReceived=0;
    this->fileNameSize=0;
 
    ui->label->setText(QString("监听"));
    ui->progressBar->reset();
}
 
void Server::acceptConnection()
{
    //获取来自客户端的连接
    this->tcpServerConnection=this->tcpServer.nextPendingConnection();
    //建立信号连接
    connect(this->tcpServerConnection,SIGNAL(readyRead()),this,SLOT(updateServerProgress()));
    connect(this->tcpServerConnection,SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(displayError(QAbstractSocket::SocketError)));
 
    ui->label->setText(QString("接收连接"));
 
    this->tcpServer.close();
}
 
void Server::updateServerProgress()
{
    QDataStream in(this->tcpServerConnection);
    in.setVersion(QDataStream::Qt_4_0);
    //如果接收到的数据小于16个字节,保存到来的文件头结构
    if(this->bytesReceived<=sizeof(qint64)*2)
    {
        if((this->tcpServerConnection->bytesAvailable()>=sizeof(qint64)*2)&&(this->fileNameSize==0))
        {
            //接收数据总大小信息和文件名大小信息
            in>>this->totalBytes>>this->fileNameSize;
            this->bytesReceived+=sizeof(qint64)*2;
        }
 
        if((this->tcpServerConnection->bytesAvailable()>=this->fileNameSize)&&(this->fileNameSize!=0))
        {
            //接收文件名,并建立文件
            in>>this->fileName;
            ui->label->setText(QString("接收文件 %1 ......").arg(this->fileName));
            this->bytesReceived+=this->fileNameSize;
            this->localFile=new QFile(this->fileName);
            if(!this->localFile->open(QFile::WriteOnly))
            {
                qDebug()<<"server: open file error"<<endl;
                return;
            }
        }
        else
        {
            return;
        }
    }
    //开始接收文件里面的数据
    if(this->bytesReceived<this->totalBytes)
    {
        this->bytesReceived+=this->tcpServerConnection->bytesAvailable();
        this->inBlock=this->tcpServerConnection->readAll();
        this->localFile->write(this->inBlock);
        this->inBlock.resize(0);
     }
 
    ui->progressBar->setMaximum(this->totalBytes);
    ui->progressBar->setValue(this->bytesReceived);
    //接收数据完成时
    if(this->bytesReceived==this->totalBytes)
    {
        this->tcpServerConnection->close();
        this->localFile->close();
        ui->pushButton->setEnabled(true);
        ui->label->setText(QString("接收文件 %1 成功").arg(this->fileName));
    }
}
 
void Server::displayError(QAbstractSocket::SocketError socketError)
{
    qDebug()<<this->tcpServerConnection->errorString();
    this->tcpServerConnection->close();
    ui->progressBar->reset();
    ui->label->setText(QString("服务端就绪"));
    ui->pushButton->setEnabled(true);
}
 
void Server::on_pushButton_clicked()
{
    start();
}
 
 
#include <QApplication>
#include "server.h"
#include <QTextCodec>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QTextCodec::setCodecForCStrings(QTextCodec::codecForLocale());
    QTextCodec::setCodecForLocale(QTextCodec::codecForLocale());
    QTextCodec::setCodecForTr(QTextCodec::codecForLocale());
 
    Server w;
    w.show();
    
    return a.exec();
}

运行结果:

加载全部内容

相关教程
猜你喜欢
用户评论