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TCP通信概述

? ?TCP(Transmission Control Protocol)是一種被大多數(shù) Internet 網(wǎng)絡(luò)協(xié)議(如 HTTP 和 FTP)用于 數(shù)據(jù)傳輸?shù)牡图?jí)網(wǎng)絡(luò)協(xié)議，它是可靠的、面向流、面向連接的傳輸協(xié)議，特別適合用于連續(xù)數(shù)據(jù)傳輸。

? ?TCP通信必須先建立TCP連接，通信端分為客戶端和服務(wù)器端。

? ?Qt提供 QTcpSocket類和QTcpServer類用于建立TCP通信應(yīng)用程 TCP Client 序。

? ?服務(wù)器端程序必須使用QTcpServer用于端口監(jiān)聽,建 立服務(wù)器;

? ?QTcpSocket用于建立連接后使用套接字(Socket) 進(jìn)行通信。

? ?QTcpServer是從QObject繼承的類，它主要用于服務(wù)器端建立網(wǎng)絡(luò)監(jiān)聽，創(chuàng)建網(wǎng)絡(luò)Socket連 接。QTcpServer類的主要接口函數(shù)見表

• void close()

  • 關(guān)閉服務(wù)器，停止網(wǎng)絡(luò)監(jiān)聽

• bool listen()

  • 在給定IP地址和端口上開始監(jiān)聽，若成功就返回true

• bool isListening()

  • 返回true表示服務(wù)器處于監(jiān)聽狀態(tài)

• QTcpSocket * nextPendingConnection()

  • 返回下一個(gè)等待接入的連接

• QHostAddress serverAddress()

  • 如果服務(wù)器處于監(jiān)聽狀態(tài)，返回服務(wù)器地址

• quint 16 serverPort()

  • 如果服務(wù)器處于監(jiān)聽狀態(tài)，返回服務(wù)器監(jiān)聽端口

• bool waitForNewConnection()

  • 以阻塞方式等待新的連接 信號(hào)

• void acceptError( QAbstractSocket::SocketError socketError)

  • 當(dāng)接受一個(gè)新的連接發(fā)生錯(cuò)誤時(shí)發(fā)射此信號(hào)，參數(shù) socketError描述了錯(cuò)誤信息

• void newConnection()

  • ?當(dāng)有新的連接時(shí)發(fā)射此信號(hào)

• void incomingConnection(qintptr socketDescriptor)

  • 當(dāng)有一個(gè)新的連接可用時(shí)，QTcpServer內(nèi)部調(diào)用此函數(shù)，創(chuàng) 建一個(gè)QTcpSocket對(duì)象，添加到內(nèi)部可用新連接列表，然 后發(fā)射newConnection()信號(hào)。用戶若從QTcpServer繼承定 義類，可以重定義此函數(shù)，但必須調(diào)用 addPendingConnection()

• void addPendingConnection(QTcpSocket ?socket)

  • 由 incomingConnection()調(diào)用，將創(chuàng)建的 QTcpSocket 添加到 內(nèi)部新可用連接列表

?? ?服務(wù)器端程序首先需要用QTcpServendisten()開始服務(wù)器端監(jiān)聽，可以指定監(jiān)聽的IP地址和 端口，一般一個(gè)服務(wù)程序只監(jiān)聽某個(gè)端口的網(wǎng)絡(luò)連接。

?? ?當(dāng)有新的客戶端接入時(shí)，QTcpServer內(nèi)部的incomingConnection()函數(shù)會(huì)創(chuàng)建一個(gè)與客戶端連 接的QTcpSocket對(duì)象，然后發(fā)射信號(hào)newConnection()。在newConnection()信號(hào)的槽函數(shù)中，可以用nextPendingConnection()接受客戶端的連接，然后使用QTcpSocket與客戶端通信。?? ??? ?

?? ?所以在客戶端與服務(wù)器建立TCP連接后，具體的數(shù)據(jù)通信是通過QTcpSocket完成的。QTcpSocket類提供了 TCP協(xié)議的接口，可以用QTcpSocket類實(shí)現(xiàn)標(biāo)準(zhǔn)的網(wǎng)絡(luò)通信協(xié)議如POP3、 SMTP和NNTP,也可以設(shè)計(jì)自定義協(xié)議。?

?? ?QTcpSocket是從QIODevice間接繼承的類，所以具有流讀寫的功能

?? ?

QTcpSocket類除了構(gòu)造函數(shù)和析構(gòu)函數(shù)，其他函數(shù)都是從QAbstractSocket繼承或重定義的。QAbstractSocket用于TCP通信的主要接口函數(shù)見表

• void connectToHost(QHostAddress?&address, quint 16 port,)

  • 以異步方式連接到指定IP地址和端口的TCP服務(wù)器，連接成功? 后會(huì)發(fā)射connected()信號(hào)

• void disconnectFromHost()

  • 斷開socket，關(guān)閉成功后發(fā)射disconnected()信號(hào)

• bool waitForConnected()

  • 等待直到建立socket連接

• bool waitForDisconnected()

  • 等待直到斷開socket連接

• QHostAddress localAddress()

  • 返回本socket的地址

• quint 16 localPort()

  • 返回本socket的端口

• QHostAddress peerAddress()

  • 在已連接狀態(tài)下，返回對(duì)方socket的地址

• QString peerName()

  • 返回connectToHost()連接到的對(duì)方的主機(jī)名

• quintl6 peerPort()

  • 在已連接狀態(tài)下，返回對(duì)方socket的端口

• qint64 readBufferSize()

  • 返回內(nèi)部讀取緩沖區(qū)的大小，該大小決定了 read()和 readAII()函數(shù)能讀出的數(shù)據(jù)的大小

• void setReadBufferSize(qint64 size)

  • 設(shè)置內(nèi)部讀取緩沖區(qū)大小

• qint64 bytesAvailable()

  • 返回需要讀取的緩沖區(qū)的數(shù)據(jù)的字節(jié)數(shù)

• bool canReadLine()

  • 如果有行數(shù)據(jù)要從socket緩沖區(qū)讀取，就返回true

• SocketState state()

  • 返回socket當(dāng)前的狀態(tài)

• void connected()

  • connectToHost()成功連接到服務(wù)器后發(fā)射此信號(hào)

• void disconnected()

  • 當(dāng)socket斷開連接后發(fā)射此信號(hào)

• void error(QAbstractSocket::SocketError socketError)

  • 當(dāng)socket發(fā)生錯(cuò)誤時(shí)發(fā)射此信號(hào)

• void hostFound()

  • 調(diào)用connectToHost()找到主機(jī)后發(fā)射此信號(hào)

• void stateChanged(QAbstractSocket::SocketState socketState)

  • 當(dāng) socket的狀態(tài)變化時(shí)發(fā)射此信號(hào)，參數(shù)socketState表示了socket 當(dāng)前的狀態(tài)

• void readyRead()

  • 當(dāng)緩沖區(qū)有新數(shù)據(jù)需要讀取時(shí)發(fā)射此信號(hào)，在此信號(hào)的槽函數(shù)里 讀取緩沖區(qū)的數(shù)據(jù)

?? ?TCP客戶端使用QTcpSocket與TCP服務(wù)器建立連接并通信

?? ?客戶端的QTcpSocket實(shí)例首先通過connectToHost()嘗試連接到服務(wù)器，需要指定服務(wù)器的IP地址和端口.connectToHost()是異步方式連接服務(wù)器，不會(huì)阻塞程序運(yùn)行，連接后發(fā)射connected()信號(hào)。

?? ?如果需要使用阻塞方式連接服務(wù)器，則使用waitForConnected()函數(shù)阻塞程序運(yùn)行，直到連接 成功或失敗。例如：?

socket->connectToHost("192.168.1.100", 1340); if (socket->waitForConnected(1000)) qDebug("Connected!");

?? ?與服務(wù)器端建立socket連接后，就可以向緩沖區(qū)寫數(shù)據(jù)或從接收緩沖區(qū)讀取數(shù)據(jù)，實(shí)現(xiàn)數(shù)據(jù)的通信。當(dāng)緩沖區(qū)有新數(shù)據(jù)進(jìn)入時(shí)，會(huì)發(fā)射readyRead()信號(hào)，一般在此信號(hào)的槽函數(shù)里讀取緩沖區(qū)數(shù)據(jù)。

?? ?QTcpSocket是從QIODevice間接繼承的，所以可以使用流數(shù)據(jù)讀寫功能。—個(gè)QTcpSocket 實(shí)例既可以接收數(shù)據(jù)也可以發(fā)送數(shù)據(jù)，且接收與發(fā)射是異步工作的，有各自的緩沖區(qū)。?

?? ?作為演示TCP通信的實(shí)例，創(chuàng)建了一個(gè)TCPClient程序和一個(gè)TCPServer程序

TCPServer程序具有如下的功能：?

?? ??根據(jù)指定IP地址(本機(jī)地址)和端口打開網(wǎng)絡(luò)監(jiān)聽，有客戶端連接時(shí)創(chuàng)建socket連接;?

?? ??采用基于行的數(shù)據(jù)通信協(xié)議，可以接收客戶端發(fā)來的消息，也可以向客戶端發(fā)送消息；?

?? ??在狀態(tài)欄顯示服務(wù)器監(jiān)聽狀態(tài)和socket的狀態(tài)。?

頭文件

#pragma once#include #include "Ui_QGuiTcpServer.h"#include #include #include class QGuiTcpServer : public QMainWindow{ Q_OBJECTpublic: QGuiTcpServer(QWidget *parent = Q_NULLPTR); ~QGuiTcpServer();private slots: void actStart_triggered();//開始監(jiān)聽 void actStop_triggered(); void actHostInfo_triggered(); void actClear_triggered(); void btnSend_clicked(); void onNewConnection(); void onSocketStateChange(QAbstractSocket::SocketState socketState); void onClientConnected(); //Client Socket connected void onClientDisconnected();//Client Socket disconnected void onSocketReadyRead();//讀取socket傳入的數(shù)據(jù)private: Ui::QTcpServer ui;protected: void closeEvent(QCloseEvent* event);private: QLabel* m_pLabListen;//狀態(tài)欄標(biāo)簽 QLabel* m_pLabSocketState;//狀態(tài)欄標(biāo)簽 QTcpServer* m_pTcpServer;//tcp服務(wù)器 QTcpSocket* m_pTcpSocket;//tcp通信的Socket QString getLocalIP();//獲取本機(jī)IP地址};

源文件

#include "QGuiTcpServer.h"#include #include #pragma execution_character_set("utf-8")QGuiTcpServer::QGuiTcpServer(QWidget *parent) : QMainWindow(parent){ ui.setupUi(this); m_pLabListen = new QLabel("監(jiān)聽狀態(tài)："); m_pLabListen->setMinimumWidth(150); ui.statusBar->addWidget(m_pLabListen); m_pLabSocketState = new QLabel("狀態(tài)："); m_pLabSocketState->setMinimumWidth(200); ui.statusBar->addWidget(m_pLabSocketState); QString localIP = getLocalIP();//本機(jī)IP setWindowTitle(windowTitle() + "----本機(jī)IP：" + localIP); ui.comboIP->addItem(localIP); m_pTcpServer = new QTcpServer(this); connect(m_pTcpServer, SIGNAL(newConnection()), this, SLOT(onNewConnection())); connect(ui.actStart, SIGNAL(triggered()), this, SLOT(actStart_triggered())); connect(ui.actStop, SIGNAL(triggered()), this, SLOT(actStop_triggered())); connect(ui.actHostInfo, SIGNAL(triggered()), this, SLOT(actHostInfo_triggered())); connect(ui.actClear, SIGNAL(triggered()), this, SLOT(actClear_triggered())); connect(ui.btnSend, SIGNAL(clicked()), this, SLOT(btnSend_clicked()));}QGuiTcpServer::~QGuiTcpServer(){}//開始監(jiān)聽void QGuiTcpServer::actStart_triggered(){ QString IP = ui.comboIP->currentText();//IP地址 quint16 port = ui.spinPort->value();//端口 QHostAddress addr(IP); m_pTcpServer->listen(addr, port);// //m_pLabListen->listen(QHostAddress::LocalHost,port);// Equivalent to QHostAddress("127.0.0.1"). ui.plainTextEdit->appendPlainText("**開始監(jiān)聽..."); ui.plainTextEdit->appendPlainText("**服務(wù)器地址："+ m_pTcpServer->serverAddress().toString()); ui.plainTextEdit->appendPlainText("**服務(wù)器端口："+ QString::number(m_pTcpServer->serverPort())); ui.actStart->setEnabled(false); ui.actStop->setEnabled(true); m_pLabListen->setText("監(jiān)聽狀態(tài)：正在監(jiān)聽");}void QGuiTcpServer::actStop_triggered(){ if (m_pTcpServer->isListening()) //tcpServer正在監(jiān)聽 { m_pTcpServer->close();//停止監(jiān)聽 ui.actStart->setEnabled(true); ui.actStop->setEnabled(false); m_pLabListen->setText("監(jiān)聽狀態(tài)：已停止監(jiān)聽"); }}void QGuiTcpServer::actHostInfo_triggered(){ QString hostName = QHostInfo::localHostName();//本地主機(jī)名 ui.plainTextEdit->appendPlainText("本機(jī)主機(jī)名：" + hostName + "\n"); QHostInfo hostInfo = QHostInfo::fromName(hostName); QList addList = hostInfo.addresses();// if (!addList.isEmpty()) { for (int i = 0; i < addList.count(); i++) { QHostAddress aHost = addList.at(i); if (QAbstractSocket::IPv4Protocol == aHost.protocol()) { QString IP = aHost.toString(); ui.plainTextEdit->appendPlainText("本機(jī)IP地址：" + aHost.toString()); if (ui.comboIP->findText(IP) < 0) ui.comboIP->addItem(IP); } } }}void QGuiTcpServer::actClear_triggered(){ ui.plainTextEdit->clear();}void QGuiTcpServer::btnSend_clicked(){ QString msg = ui.editMsg->text(); ui.plainTextEdit->appendPlainText("[out] " + msg); ui.editMsg->clear(); ui.editMsg->setFocus(); QByteArray str = msg.toUtf8(); str.append('\n');//添加一個(gè)換行符 m_pTcpSocket->write(str);}void QGuiTcpServer::onNewConnection(){ m_pTcpSocket = m_pTcpServer->nextPendingConnection(); //創(chuàng)建socket connect(m_pTcpSocket, SIGNAL(connected()), this, SLOT(onClientConnected())); onClientConnected(); connect(m_pTcpSocket, SIGNAL(disconnected()), this, SLOT(onClientDisconnected())); connect(m_pTcpSocket, SIGNAL(stateChanged(QAbstractSocket::SocketState)), this, SLOT(onSocketStateChange(QAbstractSocket::SocketState))); onSocketStateChange(m_pTcpSocket->state()); connect(m_pTcpSocket, SIGNAL(readyRead()), this, SLOT(onSocketReadyRead()));}void QGuiTcpServer::onSocketStateChange(QAbstractSocket::SocketState socketState){ switch (socketState) { case QAbstractSocket::UnconnectedState: m_pLabSocketState->setText("scoket狀態(tài)：UnconnectedState"); break; case QAbstractSocket::HostLookupState: m_pLabSocketState->setText("scoket狀態(tài)：HostLookupState"); break; case QAbstractSocket::ConnectingState: m_pLabSocketState->setText("scoket狀態(tài)：ConnectingState"); break; case QAbstractSocket::ConnectedState: m_pLabSocketState->setText("scoket狀態(tài)：ConnectedState"); break; case QAbstractSocket::BoundState: m_pLabSocketState->setText("scoket狀態(tài)：BoundState"); break; case QAbstractSocket::ClosingState: m_pLabSocketState->setText("scoket狀態(tài)：ClosingState"); break; case QAbstractSocket::ListeningState: m_pLabSocketState->setText("scoket狀態(tài)：ListeningState"); }}//客戶端接入時(shí)void QGuiTcpServer::onClientConnected(){ ui.plainTextEdit->appendPlainText("**client socket connected"); ui.plainTextEdit->appendPlainText("**peer address:" + m_pTcpSocket->peerAddress().toString()); ui.plainTextEdit->appendPlainText("**peer port:" + QString::number(m_pTcpSocket->peerPort()));}//客戶端斷開連接時(shí)void QGuiTcpServer::onClientDisconnected(){ ui.plainTextEdit->appendPlainText("**client socket disconnected"); m_pTcpSocket->deleteLater();}//讀取緩沖區(qū)行文本void QGuiTcpServer::onSocketReadyRead(){ while (m_pTcpSocket->canReadLine()) ui.plainTextEdit->appendPlainText("[in] " + m_pTcpSocket->readLine());}//關(guān)閉窗口時(shí)停止監(jiān)聽void QGuiTcpServer::closeEvent(QCloseEvent* event){ if (m_pTcpServer->isListening()) m_pTcpServer->close();;//停止網(wǎng)絡(luò)監(jiān)聽 event->accept();}//獲取本機(jī)IP地址QString QGuiTcpServer::getLocalIP(){ QString hostName = QHostInfo::localHostName();//本機(jī)主機(jī)名 QHostInfo hostInfo = QHostInfo::fromName(hostName); QString localIP = ""; QList addList = hostInfo.addresses();// if (!addList.isEmpty()) { for (int i = 0; i < addList.count(); i++) { QHostAddress aHost = addList.at(i); if (QAbstractSocket::IPv4Protocol == aHost.protocol()) { localIP = aHost.toString(); break; } } } return localIP;}

TCPClient程序程序具有如下的功能：

?? ??通過IP地址和端口號(hào)連接到服務(wù)器；?

?? ??采用基于行的數(shù)據(jù)通信協(xié)議，與服務(wù)器端收發(fā)消息：?

?? ??處理QTcpSocket的StateChange()信號(hào)，在狀態(tài)欄顯示socket的狀態(tài)。

頭文件

#pragma once#include #include "ui_QGuiTcpClient.h"#include #include class QGuiTcpClient : public QMainWindow{ Q_OBJECTpublic: QGuiTcpClient(QWidget *parent = Q_NULLPTR); ~QGuiTcpClient();private slots: //自定義槽函數(shù) void onConnected(); void onDisconnected(); void onSocketStateChange(QAbstractSocket::SocketState socketState); void onSocketReadyRead();//讀取socket傳入的數(shù)據(jù) void actConnect_triggered(); void actDisconnect_triggered(); void actClear_triggered(); void btnSend_clicked();private: Ui::QGuiTcpClient ui;protected: void closeEvent(QCloseEvent* event);private: QTcpSocket* m_pTcpClient; //socket QLabel* m_pLabSocketState;//狀態(tài)欄標(biāo)簽 QString getLocalIP();//獲取本機(jī)IP地址};

源文件

#include "QGuiTcpClient.h"#include #include #pragma execution_character_set("utf-8")QGuiTcpClient::QGuiTcpClient(QWidget* parent) : QMainWindow(parent){ ui.setupUi(this); m_pTcpClient = new QTcpSocket(this); //創(chuàng)建socket變量 m_pLabSocketState = new QLabel("Socket狀態(tài)：");//狀態(tài)欄標(biāo)簽 m_pLabSocketState->setMinimumWidth(250); ui.statusBar->addWidget(m_pLabSocketState); QString localIP = getLocalIP();//本機(jī)IP this->setWindowTitle(this->windowTitle() + "----本機(jī)IP：" + localIP); ui.comboServer->addItem(localIP); connect(m_pTcpClient, SIGNAL(connected()), this, SLOT(onConnected())); connect(m_pTcpClient, SIGNAL(disconnected()), this, SLOT(onDisconnected())); connect(m_pTcpClient, SIGNAL(stateChanged(QAbstractSocket::SocketState)), this, SLOT(onSocketStateChange(QAbstractSocket::SocketState))); connect(m_pTcpClient, SIGNAL(readyRead()), this, SLOT(onSocketReadyRead())); connect(ui.actConnect, SIGNAL(triggered()), this, SLOT(actConnect_triggered())); connect(ui.actDisconnect, SIGNAL(triggered()), this, SLOT(actDisconnect_triggered())); connect(ui.actClear, SIGNAL(triggered()), this, SLOT(actClear_triggered())); connect(ui.btnSend, SIGNAL(clicked()), this, SLOT(btnSend_clicked()));}QGuiTcpClient::~QGuiTcpClient(){}void QGuiTcpClient::onConnected(){ ui.plainTextEdit->appendPlainText("**已連接到服務(wù)器"); ui.plainTextEdit->appendPlainText("**peer address:" + m_pTcpClient->peerAddress().toString()); ui.plainTextEdit->appendPlainText("**peer port:" + QString::number(m_pTcpClient->peerPort())); ui.actConnect->setEnabled(false); ui.actDisconnect->setEnabled(true);}void QGuiTcpClient::onDisconnected(){ ui.plainTextEdit->appendPlainText("**已斷開與服務(wù)器的連接"); ui.actConnect->setEnabled(true); ui.actDisconnect->setEnabled(false);}void QGuiTcpClient::onSocketStateChange(QAbstractSocket::SocketState socketState){ switch (socketState) { case QAbstractSocket::UnconnectedState: m_pLabSocketState->setText("scoket狀態(tài)：UnconnectedState"); break; case QAbstractSocket::HostLookupState: m_pLabSocketState->setText("scoket狀態(tài)：HostLookupState"); break; case QAbstractSocket::ConnectingState: m_pLabSocketState->setText("scoket狀態(tài)：ConnectingState"); break; case QAbstractSocket::ConnectedState: m_pLabSocketState->setText("scoket狀態(tài)：ConnectedState"); break; case QAbstractSocket::BoundState: m_pLabSocketState->setText("scoket狀態(tài)：BoundState"); break; case QAbstractSocket::ClosingState: m_pLabSocketState->setText("scoket狀態(tài)：ClosingState"); break; case QAbstractSocket::ListeningState: m_pLabSocketState->setText("scoket狀態(tài)：ListeningState"); }}void QGuiTcpClient::onSocketReadyRead(){ while (m_pTcpClient->canReadLine()) ui.plainTextEdit->appendPlainText("[in] " + m_pTcpClient->readLine());}void QGuiTcpClient::actConnect_triggered(){ QString addr = ui.comboServer->currentText(); quint16 port = ui.spinPort->value(); m_pTcpClient->connectToHost(addr, port);}void QGuiTcpClient::actDisconnect_triggered(){ if (m_pTcpClient->state() == QAbstractSocket::ConnectedState) m_pTcpClient->disconnectFromHost();}void QGuiTcpClient::actClear_triggered(){ ui.plainTextEdit->clear();}void QGuiTcpClient::btnSend_clicked(){ QString msg = ui.editMsg->text(); ui.plainTextEdit->appendPlainText("[out] " + msg); ui.editMsg->clear(); ui.editMsg->setFocus(); QByteArray str = msg.toUtf8(); str.append('\n'); m_pTcpClient->write(str);}void QGuiTcpClient::closeEvent(QCloseEvent* event){ if (m_pTcpClient->state() == QAbstractSocket::ConnectedState) m_pTcpClient->disconnectFromHost(); event->accept();}QString QGuiTcpClient::getLocalIP(){ QString hostName = QHostInfo::localHostName();//本地主機(jī)名 QHostInfo hostInfo = QHostInfo::fromName(hostName); QString localIP = ""; QList addList = hostInfo.addresses();// if (!addList.isEmpty()) { for (int i = 0; i < addList.count(); i++) { QHostAddress aHost = addList.at(i); if (QAbstractSocket::IPv4Protocol == aHost.protocol()) { localIP = aHost.toString(); break; } } } return localIP;}

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