Qt学习之路_5(Qt TCP的初步使用)

在上一篇博文Qt学习之路_4(Qt UDP的初步使用) 中，初步了解了Qt下UDP的使用，这一节就学习下TCP的使用。2者其实流程都差不多。当然了，本文还是参考的《Qt及Qt Quick开发实战精解》一书中的第5个例子，即局域网聊天工具中的UDP聊天和TCP文件传送部分。另外http://www.yafeilinux.com/
上有其源码和相关教程下载。
其发送端界面如下：

　　


接收端界面如下：

　　


发送端，也即承担服务器角色的操作：

在主界面程序右侧选择一个需要发送文件的用户，弹出发送端界面后，点击打开按钮，在本地计算机中选择需要发送的文件，点击发送按钮，则进度条上会显示当前文件传送的信息，有已传送文件大小信息，传送速度等信息。如果想关闭发送过程，则单击关闭按钮。

其流程图如下：

　　


接收端，也即承担客户端角色的操作：

当在主界面中突然弹出一个对话框，问是否接自某个用户名和IP地址的文件传送信息，如果接受则单击yes按钮，否则就单击no按钮。当接收文件时，选择好接收文件所存目录和文件名后就开始接收文件了，其过程也会显示已接收文件的大小，接收速度和剩余时间的大小等信息。

其流程图如下：

　　


TCP部分程序代码和注释如下：

Widget.h:

#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
class QUdpSocket;
class TcpServer;//可以这样定义类？不用保护头文件的？
namespace Ui {
class Widget;
}
// 枚举变量标志信息的类型，分别为消息，新用户加入，用户退出，文件名，拒绝接受文件
enum MessageType{Message, NewParticipant, ParticipantLeft, FileName, Refuse};
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
protected:
void newParticipant(QString userName,
QString localHostName, QString ipAddress);
void participantLeft(QString userName,
QString localHostName, QString time);
void sendMessage(MessageType type, QString serverAddress="");
QString getIP();
QString getUserName();
QString getMessage();
void hasPendingFile(QString userName, QString serverAddress,
QString clientAddress, QString fileName);
private:
Ui::Widget *ui;
QUdpSocket *udpSocket;
qint16 port;
QString fileName;
TcpServer *server;
private slots:
void processPendingDatagrams();
void on_sendButton_clicked();
void getFileName(QString);
void on_sendToolBtn_clicked();
};
#endif // WIDGET_H

Widget.cpp:

#include "widget.h"
#include "ui_widget.h"
#include <QUdpSocket>
#include <QHostInfo>
#include <QMessageBox>
#include <QScrollBar>
#include <QDateTime>
#include <QNetworkInterface>
#include <QProcess>
#include "tcpserver.h"
#include "tcpclient.h"
#include <QFileDialog>
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
udpSocket = new QUdpSocket(this);
port = 45454;
udpSocket->bind(port, QUdpSocket::ShareAddress | QUdpSocket::ReuseAddressHint);
connect(udpSocket, SIGNAL(readyRead()), this, SLOT(processPendingDatagrams()));
sendMessage(NewParticipant);
//TcpServer是tcpserver.ui对应的类，上面直接用QUdpSocket是因为没有单独的udpserver.ui类
server = new TcpServer(this);
//sendFileName()函数一发送，则触发槽函数getFileName()
connect(server, SIGNAL(sendFileName(QString)), this, SLOT(getFileName(QString)));
}
Widget::~Widget()
{
delete ui;
}
// 使用UDP广播发送信息
void Widget::sendMessage(MessageType type, QString serverAddress)
{
QByteArray data;
QDataStream out(&data, QIODevice::WriteOnly);
QString localHostName = QHostInfo::localHostName();
QString address = getIP();
out << type << getUserName() << localHostName;
switch(type)
{
case Message :
if (ui->messageTextEdit->toPlainText() == "") {
QMessageBox::warning(0,tr("警告"),tr("发送内容不能为空"),QMessageBox::Ok);
return;
}
out << address << getMessage();
1761d
ui->messageBrowser->verticalScrollBar()
->setValue(ui->messageBrowser->verticalScrollBar()->maximum());
break;
case NewParticipant :
out << address;
break;
case ParticipantLeft :
break;
case FileName : {
int row = ui->userTableWidget->currentRow();//必须选中需要发送的给谁才可以发送
QString clientAddress = ui->userTableWidget->item(row, 2)->text();//（row,,2）为ip地址
out << address << clientAddress << fileName;//发送本地ip，对方ip，所发送的文件名
break;
}
case Refuse :
out << serverAddress;
break;
}
udpSocket->writeDatagram(data,data.length(),QHostAddress::Broadcast, port);
}
// 接收UDP信息
void Widget::processPendingDatagrams()
{
while(udpSocket->hasPendingDatagrams())
{
QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
udpSocket->readDatagram(datagram.data(), datagram.size());
QDataStream in(&datagram, QIODevice::ReadOnly);
int messageType;
in >> messageType;
QString userName,localHostName,ipAddress,message;
QString time = QDateTime::currentDateTime()
.toString("yyyy-MM-dd hh:mm:ss");
switch(messageType)
{
case Message:
in >> userName >> localHostName >> ipAddress >> message;
ui->messageBrowser->setTextColor(Qt::blue);
ui->messageBrowser->setCurrentFont(QFont("Times New Roman",12));
ui->messageBrowser->append("[ " +userName+" ] "+ time);
ui->messageBrowser->append(message);
break;
case NewParticipant:
in >>userName >>localHostName >>ipAddress;
newParticipant(userName,localHostName,ipAddress);
break;
case ParticipantLeft:
in >>userName >>localHostName;
participantLeft(userName,localHostName,time);
break;
case FileName: {
in >> userName >> localHostName >> ipAddress;
QString clientAddress, fileName;
in >> clientAddress >> fileName;
hasPendingFile(userName, ipAddress, clientAddress, fileName);
break;
}
case Refuse: {
in >> userName >> localHostName;
QString serverAddress;
in >> serverAddress;
QString ipAddress = getIP();
if(ipAddress == serverAddress)
{
server->refused();
}
break;
}
}
}
}
// 处理新用户加入
void Widget::newParticipant(QString userName, QString localHostName, QString ipAddress)
{
bool isEmpty = ui->userTableWidget->findItems(localHostName, Qt::MatchExactly).isEmpty();
if (isEmpty) {
QTableWidgetItem *user = new QTableWidgetItem(userName);
QTableWidgetItem *host = new QTableWidgetItem(localHostName);
QTableWidgetItem *ip = new QTableWidgetItem(ipAddress);
ui->userTableWidget->insertRow(0);
ui->userTableWidget->setItem(0,0,user);
ui->userTableWidget->setItem(0,1,host);
ui->userTableWidget->setItem(0,2,ip);
ui->messageBrowser->setTextColor(Qt::gray);
ui->messageBrowser->setCurrentFont(QFont("Times New Roman",10));
ui->messageBrowser->append(tr("%1 在线！").arg(userName));
ui->userNumLabel->setText(tr("在线人数：%1").arg(ui->userTableWidget->rowCount()));
sendMessage(NewParticipant);
}
}
// 处理用户离开
void Widget::participantLeft(QString userName, QString localHostName, QString time)
{
int rowNum = ui->userTableWidget->findItems(localHostName, Qt::MatchExactly).first()->row();
ui->userTableWidget->removeRow(rowNum);
ui->messageBrowser->setTextColor(Qt::gray);
ui->messageBrowser->setCurrentFont(QFont("Times New Roman", 10));
ui->messageBrowser->append(tr("%1 于 %2 离开！").arg(userName).arg(time));
ui->userNumLabel->setText(tr("在线人数：%1").arg(ui->userTableWidget->rowCount()));
}
// 获取ip地址
QString Widget::getIP()
{
QList<QHostAddress> list = QNetworkInterface::allAddresses();
foreach (QHostAddress address, list) {
if(address.protocol() == QAbstractSocket::IPv4Protocol)
return address.toString();
}
return 0;
}
// 获取用户名
QString Widget::getUserName()
{
QStringList envVariables;
envVariables << "USERNAME.*" << "USER.*" << "USERDOMAIN.*"
<< "HOSTNAME.*" << "DOMAINNAME.*";
QStringList environment = QProcess::systemEnvironment();
foreach (QString string, envVariables) {
int index = environment.indexOf(QRegExp(string));
if (index != -1) {
QStringList stringList = environment.at(index).split('=');
if (stringList.size() == 2) {
return stringList.at(1);
break;
}
}
}
return "unknown";
}
// 获得要发送的消息
QString Widget::getMessage()
{
QString msg = ui->messageTextEdit->toHtml();
ui->messageTextEdit->clear();
ui->messageTextEdit->setFocus();
return msg;
}
// 发送消息
void Widget::on_sendButton_clicked()
{
sendMessage(Message);
}
// 获取要发送的文件名
void Widget::getFileName(QString name)
{
fileName = name;
sendMessage(FileName);
}
// 传输文件按钮
void Widget::on_sendToolBtn_clicked()
{
if(ui->userTableWidget->selectedItems().isEmpty())//传送文件前需选择用户
{
QMessageBox::warning(0, tr("选择用户"),
tr("请先从用户列表选择要传送的用户！"), QMessageBox::Ok);
return;
}
server->show();
server->initServer();
}
// 是否接收文件，客户端的显示
void Widget::hasPendingFile(QString userName, QString serverAddress,
QString clientAddress, QString fileName)
{
QString ipAddress = getIP();
if(ipAddress == clientAddress)
{
int btn = QMessageBox::information(this,tr("接受文件"),
tr("来自%1(%2)的文件：%3,是否接收？")
.arg(userName).arg(serverAddress).arg(fileName),
QMessageBox::Yes,QMessageBox::No);//弹出一个窗口
if (btn == QMessageBox::Yes) {
QString name = QFileDialog::getSaveFileName(0,tr("保存文件"),fileName);//name为另存为的文件名
if(!name.isEmpty())
{
TcpClient *client = new TcpClient(this);
client->setFileName(name);    //客户端设置文件名
client->setHostAddress(QHostAddress(serverAddress));    //客户端设置服务器地址
client->show();
}
} else {
sendMessage(Refuse, serverAddress);
}
}
}

Tcpserver.h:

#ifndef TCPSERVER_H
#define TCPSERVER_H
#include <QDialog>
#include <QTime>
class QFile;
class QTcpServer;
class QTcpSocket;
namespace Ui {
class TcpServer;
}
class TcpServer : public QDialog
{
Q_OBJECT
public:
explicit TcpServer(QWidget *parent = 0);
~TcpServer();
void initServer();
void refused();
protected:
void closeEvent(QCloseEvent *);
private:
Ui::TcpServer *ui;
qint16 tcpPort;
QTcpServer *tcpServer;
QString fileName;
QString theFileName;
QFile *localFile;
qint64 TotalBytes;
qint64 bytesWritten;
qint64 bytesToWrite;
qint64 payloadSize;
QByteArray outBlock;
QTcpSocket *clientConnection;
QTime time;
private slots:
void sendMessage();
void updateClientProgress(qint64 numBytes);
void on_serverOpenBtn_clicked();
void on_serverSendBtn_clicked();
void on_serverCloseBtn_clicked();
signals:
void sendFileName(QString fileName);
};
#endif // TCPSERVER_H

Tcpserver.cpp:

#include "tcpserver.h"
#include "ui_tcpserver.h"
#include <QFile>
#include <QTcpServer>
#include <QTcpSocket>
#include <QMessageBox>
#include <QFileDialog>
#include <QDebug>
TcpServer::TcpServer(QWidget *parent) :
QDialog(parent),
ui(new Ui::TcpServer)
{
ui->setupUi(this);    //每一个新类都有一个自己的ui

setFixedSize(350,180);    //初始化时窗口显示固定大小

tcpPort = 6666;        //tcp通信端口
tcpServer = new QTcpServer(this);
//newConnection表示当tcp有新连接时就发送信号
connect(tcpServer, SIGNAL(newConnection()), this, SLOT(sendMessage()));
initServer();
}
TcpServer::~TcpServer()
{
delete ui;
}
// 初始化
void TcpServer::initServer()
{
payloadSize = 64*1024;
TotalBytes = 0;
bytesWritten = 0;
bytesToWrite = 0;
ui->serverStatusLabel->setText(tr("请选择要传送的文件"));
ui->progressBar->reset();//进度条复位
ui->serverOpenBtn->setEnabled(true);//open按钮可用
ui->serverSendBtn->setEnabled(false);//发送按钮不可用

tcpServer->close();//tcp传送文件窗口不显示
}
// 开始发送数据
void TcpServer::sendMessage()    //是connect中的槽函数
{
ui->serverSendBtn->setEnabled(false);    //当在传送文件的过程中，发送按钮不可用
clientConnection = tcpServer->nextPendingConnection();    //用来获取一个已连接的TcpSocket
//bytesWritten为qint64类型，即长整型
connect(clientConnection, SIGNAL(bytesWritten(qint64)),    //?
this, SLOT(updateClientProgress(qint64)));
ui->serverStatusLabel->setText(tr("开始传送文件 %1 ！").arg(theFileName));
localFile = new QFile(fileName);    //localFile代表的是文件内容本身
if(!localFile->open((QFile::ReadOnly))){
QMessageBox::warning(this, tr("应用程序"), tr("无法读取文件 %1:\n%2")
.arg(fileName).arg(localFile->errorString()));//errorString是系统自带的信息
return;
}
TotalBytes = localFile->size();//文件总大小
//头文件中的定义QByteArray outBlock;
QDataStream sendOut(&outBlock, QIODevice::WriteOnly);//设置输出流属性
sendOut.setVersion(QDataStream::Qt_4_7);//设置Qt版本，不同版本的数据流格式不同
time.start();  // 开始计时
QString currentFile = fileName.right(fileName.size()    //currentFile代表所选文件的文件名
- fileName.lastIndexOf('/')-1);
//qint64(0)表示将0转换成qint64类型,与(qint64)0等价
//如果是，则此处为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) << currentFile;
TotalBytes += outBlock.size();//文件名大小等信息+实际文件大小
//sendOut.device()为返回io设备的当前设置，seek(0)表示设置当前pos为0
sendOut.device()->seek(0);//返回到outBlock的开始，执行覆盖操作
//发送总大小空间和文件名大小空间
sendOut << TotalBytes << qint64((outBlock.size() - sizeof(qint64)*2));
//qint64 bytesWritten;bytesToWrite表示还剩下的没发送完的数据
//clientConnection->write(outBlock)为套接字将内容发送出去，返回实际发送出去的字节数
bytesToWrite = TotalBytes - clientConnection->write(outBlock);
outBlock.resize(0);//why??
}
// 更新进度条，有数据发送时触发
void TcpServer::updateClientProgress(qint64 numBytes)
{
//qApp为指向一个应用对象的全局指针
qApp->processEvents();//processEvents为处理所有的事件？
bytesWritten += (int)numBytes;
if (bytesToWrite > 0) {    //没发送完毕
//初始化时payloadSize = 64*1024;qMin为返回参数中较小的值，每次最多发送64K的大小
outBlock = localFile->read(qMin(bytesToWrite, payloadSize));
bytesToWrite -= (int)clientConnection->write(outBlock);
outBlock.resize(0);//清空发送缓冲区
} else {
localFile->close();
}
ui->progressBar->setMaximum(TotalBytes);//进度条的最大值为所发送信息的所有长度(包括附加信息)
ui->progressBar->setValue(bytesWritten);//进度条显示的进度长度为bytesWritten实时的长度
float useTime = time.elapsed();//从time.start()还是到当前所用的时间记录在useTime中
double speed = bytesWritten / useTime;
ui->serverStatusLabel->setText(tr("已发送 %1MB (%2MB/s) "
"\n共%3MB 已用时:%4秒\n估计剩余时间：%5秒")
.arg(bytesWritten / (1024*1024))    //转化成MB
.arg(speed*1000 / (1024*1024), 0, 'f', 2)
.arg(TotalBytes / (1024 * 1024))
.arg(useTime/1000, 0, 'f', 0)    //0，‘f’,0是什么意思啊？
.arg(TotalBytes/speed/1000 - useTime/1000, 0, 'f', 0));
if(bytesWritten == TotalBytes) {    //当需发送文件的总长度等于已发送长度时，表示发送完毕！
localFile->close();
tcpServer->close();
ui->serverStatusLabel->setText(tr("传送文件 %1 成功").arg(theFileName));
}
}
// 打开按钮
void TcpServer::on_serverOpenBtn_clicked()
{
//QString fileName;QFileDialog是一个提供给用户选择文件或目录的对话框
fileName = QFileDialog::getOpenFileName(this);    //filename为所选择的文件名(包含了路径名)
if(!fileName.isEmpty())
{
//fileName.right为返回filename最右边参数大小个字文件名，theFileName为所选真正的文件名
theFileName = fileName.right(fileName.size() - fileName.lastIndexOf('/')-1);
ui->serverStatusLabel->setText(tr("要传送的文件为：%1 ").arg(theFileName));
ui->serverSendBtn->setEnabled(true);//发送按钮可用
ui->serverOpenBtn->setEnabled(false);//open按钮禁用
}
}
// 发送按钮
void TcpServer::on_serverSendBtn_clicked()
{
//tcpServer->listen函数如果监听到有连接，则返回1，否则返回0
if(!tcpServer->listen(QHostAddress::Any,tcpPort))//开始监听6666端口
{
qDebug() << tcpServer->errorString();//此处的errorString是指？
close();
return;
}
ui->serverStatusLabel->setText(tr("等待对方接收... ..."));
emit sendFileName(theFileName);//发送已传送文件的信号，在widget.cpp构造函数中的connect()触发槽函数
}
// 关闭按钮，服务器端的关闭按钮
void TcpServer::on_serverCloseBtn_clicked()
{
if(tcpServer->isListening())
{
//当tcp正在监听时，关闭tcp服务器端应用，即按下close键时就不监听tcp请求了
tcpServer->close();
if (localFile->isOpen())//如果所选择的文件已经打开，则关闭掉
localFile->close();
clientConnection->abort();//clientConnection为下一个连接？怎么理解
}
close();//关闭本ui，即本对话框
}
// 被对方拒绝
void TcpServer::refused()
{
tcpServer->close();
ui->serverStatusLabel->setText(tr("对方拒绝接收！！！"));
}
// 关闭事件
void TcpServer::closeEvent(QCloseEvent *)
{
on_serverCloseBtn_clicked();
}

Tcpclient.h:

#ifndef TCPCLIENT_H
#define TCPCLIENT_H
#include <QDialog>
#include <QHostAddress>
#include <QFile>
#include <QTime>
class QTcpSocket;
namespace Ui {
class TcpClient;
}
class TcpClient : public QDialog
{
Q_OBJECT
public:
explicit TcpClient(QWidget *parent = 0);
~TcpClient();
void setHostAddress(QHostAddress address);
void setFileName(QString fileName);
protected:
void closeEvent(QCloseEvent *);
private:
Ui::TcpClient *ui;
QTcpSocket *tcpClient;
quint16 blockSize;
QHostAddress hostAddress;
qint16 tcpPort;
qint64 TotalBytes;
qint64 bytesReceived;
qint64 bytesToReceive;
qint64 fileNameSize;
QString fileName;
QFile *localFile;
QByteArray inBlock;
QTime time;
private slots:
void on_tcpClientCancleBtn_clicked();
void on_tcpClientCloseBtn_clicked();
void newConnect();
void readMessage();
void displayError(QAbstractSocket::SocketError);
};
#endif // TCPCLIENT_H

Tcpclient.cpp:

#include "tcpclient.h"
#include "ui_tcpclient.h"
#include <QTcpSocket>
#include <QDebug>
#include <QMessageBox>
TcpClient::TcpClient(QWidget *parent) :
QDialog(parent),
ui(new Ui::TcpClient)
{
ui->setupUi(this);
setFixedSize(350,180);
TotalBytes = 0;
bytesReceived = 0;
fileNameSize = 0;
tcpClient = new QTcpSocket(this);
tcpPort = 6666;
connect(tcpClient, SIGNAL(readyRead()), this, SLOT(readMessage()));
connect(tcpClient, SIGNAL(error(QAbstractSocket::SocketError)), this,
SLOT(displayError(QAbstractSocket::SocketError)));
}
TcpClient::~TcpClient()
{
delete ui;
}
// 设置文件名
void TcpClient::setFileName(QString fileName)
{
localFile = new QFile(fileName);
}
// 设置地址
void TcpClient::setHostAddress(QHostAddress address)
{
hostAddress = address;
newConnect();
}
// 创建新连接
void TcpClient::newConnect()
{
blockSize = 0;
tcpClient->abort();        //取消已有的连接
tcpClient->connectToHost(hostAddress, tcpPort);//连接到指定ip地址和端口的主机
time.start();
}
// 读取数据
void TcpClient::readMessage()
{
QDataStream in(tcpClient);    //这里的QDataStream可以直接用QTcpSocket对象做参数
in.setVersion(QDataStream::Qt_4_7);
float useTime = time.elapsed();
if (bytesReceived <= sizeof(qint64)*2) {    //说明刚开始接受数据
if ((tcpClient->bytesAvailable()    //bytesAvailable为返回将要被读取的字节数
>= sizeof(qint64)*2) && (fileNameSize == 0))
{
//接受数据总大小信息和文件名大小信息
in>>TotalBytes>>fileNameSize;
bytesReceived += sizeof(qint64)*2;
}
if((tcpClient->bytesAvailable() >= fileNameSize) && (fileNameSize != 0)){
//开始接受文件，并建立文件
in>>fileName;
bytesReceived +=fileNameSize;
if(!localFile->open(QFile::WriteOnly)){
QMessageBox::warning(this,tr("应用程序"),tr("无法读取文件 %1:\n%2.")
.arg(fileName).arg(localFile->errorString()));
return;
}
} else {
return;
}
}
if (bytesReceived < TotalBytes) {
bytesReceived += tcpClient->bytesAvailable();//返回tcpClient中字节的总数
inBlock = tcpClient->readAll();    //返回读到的所有数据
localFile->write(inBlock);
inBlock.resize(0);
}
ui->progressBar->setMaximum(TotalBytes);
ui->progressBar->setValue(bytesReceived);
double speed = bytesReceived / useTime;
ui->tcpClientStatusLabel->setText(tr("已接收 %1MB (%2MB/s) "
"\n共%3MB 已用时:%4秒\n估计剩余时间：%5秒")
.arg(bytesReceived / (1024*1024))
.arg(speed*1000/(1024*1024),0,'f',2)
.arg(TotalBytes / (1024 * 1024))
.arg(useTime/1000,0,'f',0)
.arg(TotalBytes/speed/1000 - useTime/1000,0,'f',0));
if(bytesReceived == TotalBytes)
{
localFile->close();
tcpClient->close();
ui->tcpClientStatusLabel->setText(tr("接收文件 %1 完毕")
.arg(fileName));
}
}
// 错误处理
//QAbstractSocket类提供了所有scoket的通用功能，socketError为枚举型
void TcpClient::displayError(QAbstractSocket::SocketError socketError)
{
switch(socketError)
{
//RemoteHostClosedError为远处主机关闭了连接时发出的错误信号
case QAbstractSocket::RemoteHostClosedError : break;
default : qDebug() << tcpClient->errorString();
}
}
// 取消按钮
void TcpClient::on_tcpClientCancleBtn_clicked()
{
tcpClient->abort();
if (localFile->isOpen())
localFile->close();
}
// 关闭按钮
void TcpClient::on_tcpClientCloseBtn_clicked()
{
tcpClient->abort();
if (localFile->isOpen())
localFile->close();
close();
}
// 关闭事件
void TcpClient::closeEvent(QCloseEvent *)
{
on_tcpClientCloseBtn_clicked();
}

Main.cpp:

#include <QtGui/QApplication>
#include "widget.h"
#include <QTextCodec>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QTextCodec::setCodecForTr(QTextCodec::codecForLocale());
Widget w;
w.show();
return a.exec();
}