QT實現文件傳輸功能
本文實例為大傢分享瞭QT實現文件傳輸功能的具體代碼，供大傢參考，具體內容如下
過程如下：
1、服務器端設置監聽套接字，開始監聽；
2、客戶端在連接成功時開始傳送文件，有connected()信號連接send()槽，send()發送文件頭信息，包括文件名、文件總大小和文件名大小等；
3、傳送完文件頭信息時開始傳送文件內容，有bytesWritten(qint64)信號連接到goOnSend(qint64)槽，前者是當想套接字寫入數據時會出發的信號，即當已經想套接字寫入數據，就繼續傳送數據，有send()傳送文件頭信息開始觸發，直到文件傳完為止。
4、在服務器端，首先接收文件頭信息，然後讀取文件名來用新建文件的方式打開一個文件，然後讀取文件名即文件等大小信息，用來更新進度條和繼續接收數據；
5、實現循環傳輸，在客戶端，因為第一次send()是由connected()信號觸發的，之後的每次傳送應該手動調用send()；在服務器端，在有新數據到達時，會判斷是否為頭文件，因此在每次文件傳完的時候將byteReceived重置為0，即下一次再接收到數據的時候依據byteReceived判斷的結果就是一個新文件瞭。
客戶端代碼：
#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; //分次傳
qint64 loadSize; //每次發送數據的大小
qint64 byteToWrite; //剩餘數據大小
qint64 totalSize; //文件總大小
int sendTimes; //用來標記是否為第一次發送，第一次以後連接信號觸發，後面的則手動調用
private slots:
void send(); //傳送文件頭信息
void goOnSend(qint64); //傳送文件內容
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())); //當連接成功時，就開始傳送文件
connect(tcpClient, SIGNAL(bytesWritten(qint64)), this, SLOT(goOnSend(qint64)));
}
void Widget::send() //發送文件頭信息
{
byteToWrite = localFile->size(); //剩餘數據的大小
totalSize = localFile->size();
loadSize = 4*1024; //每次發送數據的大小
QDataStream out(&outBlock, QIODevice::WriteOnly);
QString currentFileName = fileName.right(fileName.size() - fileName.lastIndexOf('/')-1);
out<<qint64(0)<<qint64(0)<<currentFileName;
totalSize += outBlock.size(); //總大小為文件大小加上文件名等信息大小
byteToWrite += outBlock.size();
out.device()->seek(0); //回到字節流起點來寫好前面連個qint64，分別為總大小和文件名等信息大小
out<<totalSize<<qint64(outBlock.size());
tcpClient->write(outBlock); //將讀到的文件發送到套接字
ui->progressLabel->show();
ui->sendProgressBar->setMaximum(totalSize);
ui->sendProgressBar->setValue(totalSize - byteToWrite);
}
void Widget::goOnSend(qint64 numBytes) //開始發送文件內容
{
byteToWrite -= numBytes; //剩餘數據大小
outBlock = localFile->read(qMin(byteToWrite, loadSize));
tcpClient->write(outBlock);
ui->sendProgressBar->setMaximum(totalSize);
ui->sendProgressBar->setValue(totalSize - byteToWrite);
if(byteToWrite == 0) //發送完畢
ui->sendStatusLabel->setText(tr("文件發送完畢!"));
}
Widget::~Widget()
{
delete ui;
}
void Widget::on_openPushButton_clicked() //打開文件並獲取文件名（包括路徑）
{
ui->sendStatusLabel->setText(tr("正在打開文件..."));
ui->sendProgressBar->setValue(0); //非第一次發送
loadSize = 0;
byteToWrite = 0;
totalSize = 0;
outBlock.clear();
fileName = QFileDialog::getOpenFileName(this);
localFile = new QFile(fileName);
localFile->open(QFile::ReadOnly);
ui->sendStatusLabel->setText(tr("已打開文件 %1").arg(fileName));
}
void Widget::on_sendPushButton_clicked()
{
if(sendTimes == 0) //隻有第一次發送的時候，是發生在連接產生信號connect時
{
tcpClient->connectToHost(QHostAddress("192.168.1.137"), 1000);
sendTimes = 1;
}
else
send(); //第一次發送的時候是由connectToHost出發connect信號才能調用send，第二次之後就需要調用send瞭
ui->sendStatusLabel->setText(tr("正在發送文件 %1").arg(fileName));
}
服務端代碼：
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; //總共需要發送的文件大小（文件內容&文件名信息）
qint64 byteReceived; //已經發送的大小
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("已連接，正在準備接收文件!"));
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) //才剛開始接收數據，此數據為文件信息
{
ui->receivedProgressBar->setValue(0);
QDataStream in(receivedSocket);
in>>totalSize>>byteReceived>>fileName;
newFile = new QFile(fileName);
newFile->open(QFile::WriteOnly);
}
else //正式讀取文件內容
{
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("開始監聽..."));
}
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