一、了解TCP的通信过程

Qt中封装了TCP协议 QTcpServer类负责服务端：

1、创建QTcpServer对象

2、监听listen需要的参数是地址和端口号

3、当有新的客户端连接成功时会发射newConnection信号

4、在newConnection信号的槽函数中，调用nextPendingConnection函数获取新的连接QTcpSocket对象

5、连接QTcpSocket对象的readyRead信号

6、在readyRead信号的槽函数使用read接收数据

7、调用write成员函数发送数据

QTcpSocket负责客户端

1、创建qTcpSocket对象

2、当对象与Server连接成功时会发射connected信号

3、调用成员函数connectToHost连接服务器，需要的参数是地址和端口号

4、connected信号的槽函数中开启发送数据

5、使用write发送数据，read接收数据

二、实现多人聊天室

支持多人聊天(多个客户端)

每个客户端不仅能显示自己发的，还能收到别的客户端发的

服务端收到所有客户端发的

关键代码

client：

//widget.h

#ifndef WIDGET_H

#define WIDGET_H

#include #include namespace Ui {

class Widget;

}

class Widget : public QWidget

{

Q_OBJECT

QTcpSocket* tcpSocket;

public:

explicit Widget(QWidget *parent = 0);

~Widget();

private slots:

void on_send_clicked();

void connect_success();

void read_data();

private:

Ui::Widget *ui;

};

#endif // WIDGET_H

//widget.cpp

#include "widget.h"

#include "ui_widget.h"

#includeWidget::Widget(QWidget *parent) :

QWidget(parent),

ui(new Ui::Widget)

{

ui->setupUi(this);

tcpSocket = new QTcpSocket;

tcpSocket->connectToHost("192.168.43.4",1234);

connect(tcpSocket,SIGNAL(connected()),this,SLOT(connect_success()));

}

Widget::~Widget()

{

delete ui;

}

void Widget::on_send_clicked()

{

std::string msg = ui->msg->text().toStdString();

int ret = tcpSocket->write(msg.c_str(),msg.size()+1);

qDebug("--send:%d--",ret);

ui->msg->setText("");

}

void Widget::connect_success()

{

qDebug("success");

ui->send->setEnabled(true);

connect(tcpSocket,SIGNAL(readyRead()),this,SLOT(read_data()));

}

void Widget::read_data()

{

char buf[256]={};

tcpSocket->read(buf,sizeof(buf));

ui->textEdit->append(buf);

}

server:

//widget.h

#ifndef WIDGET_H

#define WIDGET_H

#include #include #include #include using namespace std;

namespace Ui {

class Widget;

}

class Widget : public QWidget

{

Q_OBJECT

QTcpServer* tcpServer;

vectorsocketArr;

public:

explicit Widget(QWidget *parent = 0);

~Widget();

public slots:

void new_connect();

void read_data();

//void send_data();

private:

Ui::Widget *ui;

};

#endif // WIDGET_H

//widget.cpp

#include "widget.h"

#include "ui_widget.h"

Widget::Widget(QWidget *parent) :

QWidget(parent),

ui(new Ui::Widget)

{

ui->setupUi(this);

tcpServer = new QTcpServer;

tcpServer->listen(QHostAddress("192.168.43.4"),1234);

connect(tcpServer,SIGNAL(newConnection()),this,SLOT(new_connect()));

}

Widget::~Widget()

{

delete ui;

}

void Widget::new_connect()

{

qDebug("--new connect--");

QTcpSocket* tcpSocket = tcpServer->nextPendingConnection();

connect(tcpSocket,SIGNAL(readyRead()),this,SLOT(read_data()));

socketArr.push_back(tcpSocket);

}

void Widget::read_data()

{

for(int i=0; ibytesAvailable())

{

char buf[256] = {};

socketArr[i]->read(buf,sizeof(buf));

char buf2[256] = {};

sprintf(buf2,"%d:%s",i,buf);

ui->textEdit->append(buf2);

for(int j=0; jwrite(buf1,sizeof(buf1));

}

}

}

}