本文实例为大家分享了QT实现文件传输功能的具体代码，供大家参考，具体内容如下
过程如下：
1、服务器端设置监听套接字，开始监听；
2、客户端在连接成功时开始传送文件，有connected()信号连接send()槽，send()发送文件头信息，包括文件名、文件总大小和文件名大小等；
3、传送完文件头信息时开始传送文件内容，有bytesWritten(qint64)信号连接到goOnSend(qint64)槽，前者是当想套接字写入数据时会出发的信号，即当已经想套接字写入数据，就继续传送数据，有send()传送文件头信息开始触发，直到文件传完为止。
4、在服务器端，首先接收文件头信息，然后读取文件名来用新建文件的方式打开一个文件，然后读取文件名即文件等大小信息，用来更新进度条和继续接收数据；
5、实现循环传输，在客户端，因为第一次send()是由connected()信号触发的，之后的每次传送应该手动调用send()；在服务器端，在有新数据到达时，会判断是否为头文件，因此在每次文件传完的时候将byteReceived重置为0，即下一次再接收到数据的时候依据byteReceived判断的结果就是一个新文件了。
客户端代码：#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QTcpSocket>
#include <QFile>
#include <string>
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
private:
Ui::Widget *ui;
QTcpSocket *tcpClient;
QFile *localFile;
QString fileName; //文件名
QByteArray outBlock; //分次传
qint64 loadSize; //每次发送数据的大小
qint64 byteToWrite; //剩余数据大小
qint64 totalSize; //文件总大小
int sendTimes; //用来标记是否为第一次发送，第一次以后连接信号触发，后面的则手动调用
private slots:
void send(); //传送文件头信息
void goOnSend(qint64); //传送文件内容
void on_openPushButton_clicked();
void on_sendPushButton_clicked();
};
#endif // WIDGET_H
widget.cpp
#include "widget.h"
#include "ui_widget.h"
#include <QHostAddress>
#include <QTextCodec>
#include <QFileDialog>
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
ui->progressLabel->hide();
QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF8"));
tcpClient = new QTcpSocket(this);
sendTimes = 0;
connect(tcpClient, SIGNAL(connected()), this, SLOT(send())); //当连接成功时，就开始传送文件
connect(tcpClient, SIGNAL(bytesWritten(qint64)), this, SLOT(goOnSend(qint64)));
}
void Widget::send() //发送文件头信息
{
byteToWrite = localFile->size(); //剩余数据的大小
totalSize = localFile->size();
loadSize = 4*1024; //每次发送数据的大小
QDataStream out(&outBlock, QIODevice::WriteOnly);
QString currentFileName = fileName.right(fileName.size() - fileName.lastIndexOf('/')-1);
out<<qint64(0)<<qint64(0)<<currentFileName;
totalSize += outBlock.size(); //总大小为文件大小加上文件名等信息大小
byteToWrite += outBlock.size();
out.device()->seek(0); //回到字节流起点来写好前面连个qint64，分别为总大小和文件名等信息大小
out<<totalSize<<qint64(outBlock.size());
tcpClient->write(outBlock); //将读到的文件发送到套接字
ui->progressLabel->show();
ui->sendProgressBar->setMaximum(totalSize);
ui->sendProgressBar->setValue(totalSize - byteToWrite);
}
void Widget::goOnSend(qint64 numBytes) //开始发送文件内容
{
byteToWrite -= numBytes; //剩余数据大小
outBlock = localFile->read(qMin(byteToWrite, loadSize));
tcpClient->write(outBlock);
ui->sendProgressBar->setMaximum(totalSize);
ui->sendProgressBar->setValue(totalSize - byteToWrite);
if(byteToWrite == 0) //发送完毕
ui->sendStatusLabel->setText(tr("文件发送完毕!"));
}
Widget::~Widget()
{
delete ui;
}
void Widget::on_openPushButton_clicked() //打开文件并获取文件名（包括路径）
{
ui->sendStatusLabel->setText(tr("正在打开文件..."));
ui->sendProgressBar->setValue(0); //非第一次发送
loadSize = 0;
byteToWrite = 0;
totalSize = 0;
outBlock.clear();
fileName = QFileDialog::getOpenFileName(this);
localFile = new QFile(fileName);
localFile->open(QFile::ReadOnly);
ui->sendStatusLabel->setText(tr("已打开文件 %1").arg(fileName));
}
void Widget::on_sendPushButton_clicked()
{
if(sendTimes == 0) //只有第一次发送的时候，是发生在连接产生信号connect时
{
tcpClient->connectToHost(QHostAddress("192.168.1.137"), 1000);
sendTimes = 1;
}
else
send(); //第一次发送的时候是由connectToHost出发connect信号才能调用send，第二次之后就需要调用send了
ui->sendStatusLabel->setText(tr("正在发送文件 %1").arg(fileName));
}
服务端代码：
widget.h
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QtNetwork/QTcpServer>
#include <QtNetwork/QTcpSocket>
#include <QFile>
#include <QString>
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
private:
Ui::Widget *ui;
QTcpServer *server;
QTcpSocket *receivedSocket;
QFile *newFile;
QByteArray inBlock;
QString fileName;
qint64 totalSize; //总共需要发送的文件大小（文件内容&文件名信息）
qint64 byteReceived; //已经发送的大小
private slots:
void acceptConnection();
void readClient();
void on_pushButton_clicked();
};
#endif // WIDGET_H
widget.cpp
#include "widget.h"
#include "ui_widget.h"
#include <QTextCodec>
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
ui->progressLabel->hide();
QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF8"));
}
void Widget::acceptConnection()
{
ui->receivedStatusLabel->setText(tr("已连接，正在准备接收文件!"));
receivedSocket = server->nextPendingConnection();
connect(receivedSocket, SIGNAL(readyRead()), this, SLOT(readClient()));
}
void Widget::readClient()
{
ui->receivedStatusLabel->setText(tr("正在接收文件..."));
if(byteReceived == 0) //才刚开始接收数据，此数据为文件信息
{
ui->receivedProgressBar->setValue(0);
QDataStream in(receivedSocket);
in>>totalSize>>byteReceived>>fileName;
newFile = new QFile(fileName);
newFile->open(QFile::WriteOnly);
}
else //正式读取文件内容
{
inBlock = receivedSocket->readAll();
byteReceived += inBlock.size();
newFile->write(inBlock);
newFile->flush();
}
ui->progressLabel->show();
ui->receivedProgressBar->setMaximum(totalSize);
ui->receivedProgressBar->setValue(byteReceived);
if(byteReceived == totalSize)
{
ui->receivedStatusLabel->setText(tr("%1接收完成").arg(fileName));
inBlock.clear();
byteReceived = 0;
totalSize = 0;
}
}
Widget::~Widget()
{
delete ui;
}
void Widget::on_pushButton_clicked()
{
totalSize = 0;
byteReceived = 0;
server = new QTcpServer(this);
server->listen(QHostAddress("192.168.1.137"), 1000);
connect(server, SIGNAL(newConnection()), this, SLOT(acceptConnection()));
ui->receivedProgressBar->setValue(0);
ui->receivedStatusLabel->setText(tr("开始监听..."));
}