QT学习点滴记录(五）

QT 网络 TCP(二) 文件传输

一、服务端

1. 新建一个QT Gui Application， 命名为“TCPReceive”， 并修改pro文件(QT += network)2. 添加所需控件， 如下图所示其中“服务器端”Label的objectName为ServerStatusLabel；进度条Progress Bar的objectName为ServerProgressBar，设置其value属性为0；“开始监听”按钮的objectName为ListenPushButton3. 修改Widget.h文件(1) 添加头文件：#include <QtNetWork>(2)添加私有变量：

Ui::Widget *ui;

QTcpServer m_TcpServer;

QTcpSocket* m_pTcpServerConnection;

qint64 m_nTotalBytes;//存放总大小信息

qint64 m_nBytesReceived;//已收到数据的大小

qint64 m_nFileNameSize;//文件名的大小信息

QString m_strFileName;//存放文件名

QFile* m_pLocalFile;//本地文件

QByteArray m_inBlock;//数据缓冲区

(3)添加槽函数

private slots:

void Listen();

void AcceptConnection();

void UpdateServerProgress();

void DiaplayError(QAbstractSocket::SocketError);

void on_ListenPushButton_clicked();

4.修改Widget.cpp文件

(1)在构造函数添加如下代码：

m_nTotalBytes = 0;

m_nBytesReceived = 0;

m_nFileNameSize = 0;

connect(&m_TcpServer, SIGNAL(newConnection()), this,SLOT(AcceptConnection()));

(2)实现槽函数

void Widget::Listen()

{

ui->ListenPushButton->setEnabled(false);

m_nBytesReceived = 0;

if(!m_TcpServer.listen(QHostAddress::LocalHost, 6666))

{

qDebug() << m_TcpServer.errorString();

close();

return ;

}

ui->ServerStatusLabel->setText(tr("监听"));

}

void Widget::AcceptConnection()

{

m_pTcpServerConnection = m_TcpServer.nextPendingConnection();

connect(m_pTcpServerConnection, SIGNAL(readyRead()), this,

SLOT(UpdateServerProgress()));

connect(m_pTcpServerConnection, SIGNAL(error(QAbstractSocket::SocketError)),

this, SLOT(DiaplayError(QAbstractSocket::SocketError)));

ui->ServerStatusLabel->setText(tr("接受连接"));

m_TcpServer.close();

}

void Widget::UpdateServerProgress()

{

QDataStream in(m_pTcpServerConnection);

in.setVersion(QDataStream::Qt_4_8);

if(m_nBytesReceived <= sizeof(qint64) * 2)

{

if(m_pTcpServerConnection->bytesAvailable() >= sizeof(qint64) * 2 && m_nFileNameSize == 0)

{

in >> m_nTotalBytes >> m_nFileNameSize;

m_nBytesReceived += sizeof(qint64) * 2;

}

if(m_pTcpServerConnection->bytesAvailable() >= m_nFileNameSize && m_nFileNameSize != 0)

{

in >> m_strFileName;

ui->ServerStatusLabel->setText(tr("接收文件 %1 ...").arg(m_strFileName));

m_nBytesReceived += m_nFileNameSize;

m_pLocalFile = new QFile(m_strFileName);

if(!m_pLocalFile->open(QFile::WriteOnly))

{

qDebug() << "Open File Error!";

return ;

}

}

else

{

    return ;

}

}

if(m_nBytesReceived < m_nTotalBytes)

{

m_nBytesReceived += m_pTcpServerConnection->bytesAvailable();

m_inBlock = m_pTcpServerConnection->readAll();

m_pLocalFile->write(m_inBlock);

m_inBlock.resize(0);

}

ui->ServerProgressBar->setMaximum(m_nTotalBytes);

ui->ServerProgressBar->setValue(m_nBytesReceived);

if(m_nBytesReceived == m_nTotalBytes)

{

m_pTcpServerConnection->close();

m_pLocalFile->close();

ui->ListenPushButton->setEnabled(true);

ui->ServerStatusLabel->setText(tr("接收文件 %1 成功! ").arg(m_strFileName));

}

}

void Widget::DiaplayError(QAbstractSocket::SocketError)

{

qDebug() << m_pTcpServerConnection->errorString();

m_pTcpServerConnection->close();

ui->ServerProgressBar->reset();

ui->ServerStatusLabel->setText(tr("服务端就绪"));

ui->ListenPushButton->setEnabled(true);

}

void Widget::on_ListenPushButton_clicked()

{

Listen();

}

5. 为了可以显示中文信息， 在main.cpp中添加如下代码：

QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));

QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));

QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));

6.编译运行， 效果如下图

二、客户端

1. 新建QT Gui Application程序， 命名为TCPSender, 并修改pro文件(添加代码：QT += network)

2. 在ui文件中添加所需控件， 示意图如下：其中“主机”的Line Edit的objectName为HostLineEdit；“端口”后的Line Edit的objectName为PortLineEdit；下面的Progress Bar的objectName为ClientProgressBar，其value属性设为0；“状态”Label的objetName为ClientStatusLabel；“打开”按钮的objectName为openButton；“发送”按钮的objectName为SendPushButton3. 修改Widget.h文件(1)添加头文件：#include <QtNetWork>(2)添加私有变量：

QTcpSocket* m_pTcpClient;

QFile* m_pLocalFile;//要发送的文件

qint64 m_nTotalBytes;//数据总大小

qint64 m_nBytesWritten;//已经发送数据大小

qint64 m_nBytesToWrite;//剩余数据大小

qint64 m_nLoadSize;//每次发送数据的大小

QString m_strFileName;//保存文件路径

QByteArray m_OutBlock;//数据缓冲区， 即存放每次要发送的数据

(3)添加槽函数：

private slots:

void Send();    //连接服务器

void StartTransfer();   //发送文件大小等信息

void UpdateClientProgress(qint64);  //发送数据， 更新进度条

void DiaplayError(QAbstractSocket::SocketError);    //显示错误

void OpenFile();    //打开文件

void on_OpenPushButton_clicked();

void on_SendPushButton_clicked();

4.修改Widget.cpp文件

(1)在构造函数中添加如下代码：

m_nLoadSize = 4 * 1024;

m_nTotalBytes = 0;

m_nBytesWritten = 0;

m_nBytesToWrite = 0;

m_pTcpClient = new QTcpSocket(this);

//当连接服务器成功时， 发出connected信号， 开始传送文件

connect(m_pTcpClient, SIGNAL(connected()), this,SLOT(StartTransfer()));

//当有数据发送成功时， 更新进度条

connect(m_pTcpClient, SIGNAL(bytesWritten(qint64)), this,SLOT(UpdateClientProgress(qint64)));

connect(m_pTcpClient, SIGNAL(error(QAbstractSocket::SocketError)),this, SLOT(DiaplayError(QAbstractSocket::SocketError)));

//设置“发送”按钮不可用

ui->SendPushButton->setEnabled(false);

(2)实现槽函数

void Widget::OpenFile()

{

m_strFileName = QFileDialog::getOpenFileName(this);

if(!m_strFileName.isEmpty())

{

ui->SendPushButton->setEnabled(true);

ui->ClientStatusLabel->setText(tr("打开文件 %1 成功！").arg(m_strFileName));

}

}

void Widget::Send()

{

//设置发送按钮不可用

ui->SendPushButton->setEnabled(false);

//初始化已发送字节为0

m_nBytesWritten = 0;

ui->ClientStatusLabel->setText(tr("连接中..."));

m_pTcpClient->connectToHost(ui->HostLineEdit->text(), ui->PortLineEdit->text().toInt());

}

void Widget::StartTransfer()

{

m_pLocalFile = new QFile(m_strFileName);

if(!m_pLocalFile->open(QFile::ReadOnly))

{

qDebug() << "Open File Error!";

return ;

}

m_nTotalBytes = m_pLocalFile->size();

QDataStream sendOut(&m_OutBlock, QIODevice::WriteOnly);

sendOut.setVersion(QDataStream::Qt_4_8);

QString currentFileName = m_strFileName.right(m_strFileName.size() - m_strFileName.lastIndexOf('/') - 1);

//依次写入总大小信息空间， 文件名大小信息空间， 文件名

sendOut << qint64(0) << qint64(0) << currentFileName;

//这里的总大小是文件名大小等信息和实际文件大小的总和

m_nTotalBytes += m_OutBlock.size();

sendOut.device()->seek(0);

//返回m_OutBlock的开始， 用实际的大小信息代替两个qint64(0)空间

sendOut << m_nTotalBytes << qint64(m_OutBlock.size() - sizeof(qint64) * 2);

//发送完头数据后剩余数据的大小

m_nBytesToWrite = m_nTotalBytes - m_pTcpClient->write(m_OutBlock);

ui->ClientStatusLabel->setText(tr("已连接"));

m_OutBlock.resize(0);

}

void Widget::UpdateClientProgress(qint64 numBytes)

{

//已经发送数据的大小

m_nBytesWritten += (int)numBytes;

//如果已经发送了数据

if(m_nBytesToWrite > 0)

{

//每次发送m_nLoadSize大小的数据， 这里设置为4KB， 如果剩余的数据不足， 就发送剩余数据的大小

m_OutBlock = m_pLocalFile->read(qMin(m_nBytesToWrite, m_nLoadSize));

//发送完一次数据后剩余数据的大小

m_nBytesToWrite -= (int)m_pTcpClient->write(m_OutBlock);

//清空发送缓冲区

    m_OutBlock.resize(0);

}

else    //如果没有发送任何数据， 则关闭文件

{

m_pLocalFile->close();

}

//更新进度条

ui->ClientProgressBar->setMaximum(m_nTotalBytes);

ui->ClientProgressBar->setValue(m_nBytesWritten);

//发送完毕

if(m_nBytesWritten == m_nTotalBytes)

{

ui->ClientStatusLabel->setText(tr("传送文件 %1 成功").arg(m_strFileName));

m_pLocalFile->close();

m_pTcpClient->close();

}

}

void Widget::DiaplayError(QAbstractSocket::SocketError)

{

qDebug() << m_pTcpClient->errorString();

m_pTcpClient->close();

ui->ClientProgressBar->reset();

ui->ClientStatusLabel->setText(tr("客户端准备就绪"));

ui->SendPushButton->setEnabled(true);

}

void Widget::on_OpenPushButton_clicked()

{

OpenFile();

}

void Widget::on_SendPushButton_clicked()

{

Send();

}

5.为了可以显示中文信息， 在main.cpp中添加如下代码：

QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));

QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));

QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));

6. 编译运行， 效果图如下：

7. 运行服务端， 然后点击监听按钮， 点击客户端中打开按钮， 选择本地文件， 进行传输， 示意图如下