基于Qt开发的多线程TCP服务端

成果展示：

一、Qt TCP服务端开发环境准备

1. 项目配置

在Qt Creator中新建控制台或GUI项目，需在.pro文件中添加网络模块依赖：

QT += network  # 引用网络库

该配置使项目支持QTcpServer和QTcpSocket类，这是实现TCP通信的核心组件。

2. 核心类说明

• QTcpServer：负责监听端口并接受客户端连接请求，通过incomingConnection(qintptr socketDescripto)信号触发新连接处理。
• QTcpSocket：用于与客户端建立通信通道，支持异步数据读写和状态管理。

二、服务端搭建步骤详解

步骤1：初始化服务端对象

 	m_port = 9999;//监听端口号m_maxConns = 100;//最大连接数this->setMaxPendingConnections(m_maxConns);

步骤2：启动端口监听

//监听端口if (!this->listen(QHostAddress::Any, port)){qDebug()<<"TCP服务端启动失败，请检查端口是否被占用";return false;}m_isRunning = true;qDebug()<<"TCP服务端启动成功，IP:"<<this->serverAddress().toIPv4Address()<<",端口:"<<port;

步骤3：处理客户端连接

void TcpServer::incomingConnection(qintptr socketDescriptor)
{Session *session = new Session(socketDescriptor);session->moveToThread(m_thread);connect(session,&Session::disconn,this,[session](){session->deleteLater();});connect(session,&Session::disconn,this,&TcpServer::OnDisConnectedToHost);connect(session,&Session::activeconn,this,&TcpServer::OnActiveConn);m_socketMap.insert(socketDescriptor,session);qInfo()<<QString("有新的客户端连接，%1:%2").arg(session->peerAddress().toString()).arg(session->peerPort());OnActiveConn(socketDescriptor);if(!m_thread->isRunning()){m_thread->start();}
}

此处通过incomingConnection获取与客户端通信的套接字对象，并关联数据接收和断开事件。

三、数据通信与状态管理

1. 数据收发实现

• 发送数据：通过套接字write()方法写入字节流。

void Session::sendMsg(const QString msg)
{this->write(msg.toUtf8());this->flush(); // 确保数据立即发送
}

• 接收数据：监听readyRead()信号，调用readAll()获取内容。

void Session::recvMsg()
{emit activeconn(m_socketDescriptor);QByteArray msg;msg.append(this->readAll());while(this->bytesAvailable()>0){this->waitForReadyRead(10);msg.append(this->readAll());}QTextCodec *codec = QTextCodec::codecForName("GBK");QString data = codec->toUnicode(msg);qDebug()<<data;
}

2. 客户端状态监控

• 断开检测：通过disconnected()信号触发清理操作

void Session::disconnectedToHost()
{QString ip = this->peerAddress().toString();qDebug()<<QString("客户端%1:%2断开连接").arg(ip).arg(this->peerPort());this->close();emit disconn(m_socketDescriptor);
}

四、进阶功能扩展

1. 多客户端并发处理

Qt通过为每个连接创建独立QTcpSocket实现多线程通信。可通过容器管理多个套接字：

	session->moveToThread(m_thread);m_socketMap.insert(socketDescriptor,session);

2. 心跳检测机制

定时发送心跳包验证连接活性：

void TcpServer::OnDelInvalidConn()
{QVector<qintptr> socketDescriptorVec;uint stamp = QDateTime::currentDateTime().toTime_t();foreach (const auto it,m_socketTimeout.keys()) {if(qAbs(stamp-m_socketTimeout.value(it))>600){socketDescriptorVec.push_back(it);}}foreach (const auto it,socketDescriptorVec) {m_socketMap.value(it)->disconn(it);}socketDescriptorVec.clear();
}void TcpServer::OnActiveConn(qintptr socketDescriptor)
{m_socketTimeout.insert(socketDescriptor,QDateTime::currentDateTime().toTime_t());
}

五、调试与优化建议

1. 网络调试工具

使用Telnet或TCP/UDP调试助手（如NetAssist）验证服务端功能。
测试命令示例：

telnet 127.0.0.1 9999

2. 错误处理

• 监听失败时检查端口占用（QAbstractSocket::AddressInUseError）
• 使用QSocketNotifier监控异常状态（需启用事件循环）

3. 性能优化

• 设置接收缓冲区大小：socket->setReadBufferSize(1024*1024)
• 启用Nagle算法优化小数据包：socket->setSocketOption(QAbstractSocket::LowDelayOption, 0)

六、完整代码示例：

1.tcpserver.h

#ifndef TCPSERVER_H
#define TCPSERVER_H#include<QObject>
#include<QtNetwork/QTcpServer>
#include "session.h"
#include<QTimer>
#include<QThreadPool>
#include<QThread>
class TcpServer:public QTcpServer
{Q_OBJECT
public:TcpServer();~TcpServer();bool startTcpServer(quint16 port);void stopTcpServer();bool isStart();protected:void incomingConnection(qintptr socketDescriptor);
public slots:void OnDisConnectedToHost(qintptr socketDescriptor);void OnDelInvalidConn();//删除无效连接void OnActiveConn(qintptr socketDescriptor);//活跃连接
private:unsigned int m_maxConnections;			//最大连接数bool m_isRunning;						//判断服务启动状态，false停止，true运行QList<QTcpSocket*> m_socketList;QMap<qintptr,Session*> m_socketMap;QMap<qintptr,uint> m_socketTimeout;int m_port;int m_maxConns;QTimer m_timer;QThread *m_thread;};
#endif // TCPSERVER_H

2.tcpserver.cpp

#include "tcpserver.h"
#include <QDateTime>TcpServer::TcpServer()
{m_isRunning = false;m_socketMap.clear();m_thread = new QThread;m_port = 9999;m_maxConns = 100;this->setMaxPendingConnections(m_maxConns);startTcpServer(m_port);connect(&m_timer,&QTimer::timeout,this,&TcpServer::OnDelInvalidConn);m_timer.start(5*60*1000);
}TcpServer::~TcpServer()
{m_timer.stop();m_socketMap.clear();stopTcpServer();m_thread->quit();m_thread->wait();m_thread->deleteLater();
}bool TcpServer::startTcpServer(quint16 port)
{if (isStart())return true;//监听端口if (!this->listen(QHostAddress::Any, port)){qDebug()<<"TCP服务端启动失败，请检查端口是否被占用";return false;}m_isRunning = true;qDebug()<<"TCP服务端启动成功，IP:"<<this->serverAddress().toIPv4Address()<<",端口:"<<port;return true;
}void TcpServer::stopTcpServer()
{if (!isStart())return;//关闭监听this->close();m_isRunning = false;
}bool TcpServer::isStart()
{return m_isRunning;
}void TcpServer::incomingConnection(qintptr socketDescriptor)
{Session *session = new Session(socketDescriptor);session->moveToThread(m_thread);connect(session,&Session::disconn,this,[session](){session->deleteLater();});connect(session,&Session::disconn,this,&TcpServer::OnDisConnectedToHost);connect(session,&Session::activeconn,this,&TcpServer::OnActiveConn);m_socketMap.insert(socketDescriptor,session);qInfo()<<QString("有新的客户端连接，%1:%2").arg(session->peerAddress().toString()).arg(session->peerPort());OnActiveConn(socketDescriptor);if(!m_thread->isRunning()){m_thread->start();}
}void TcpServer::OnDisConnectedToHost(qintptr socketDescriptor)
{m_socketMap.remove(socketDescriptor);m_socketTimeout.remove(socketDescriptor);
}void TcpServer::OnDelInvalidConn()
{QVector<qintptr> socketDescriptorVec;uint stamp = QDateTime::currentDateTime().toTime_t();foreach (const auto it,m_socketTimeout.keys()) {if(qAbs(stamp-m_socketTimeout.value(it))>600){socketDescriptorVec.push_back(it);}}foreach (const auto it,socketDescriptorVec) {m_socketMap.value(it)->disconn(it);}socketDescriptorVec.clear();
}void TcpServer::OnActiveConn(qintptr socketDescriptor)
{m_socketTimeout.insert(socketDescriptor,QDateTime::currentDateTime().toTime_t());
}

3.session.h

#ifndef SESSION_H
#define SESSION_H#include<QtNetwork/QTcpSocket>
#include<QObject>class Session:public QTcpSocket
{Q_OBJECT
public:Session(qintptr socketDescriptor);~Session();void sendMsg(const QString msg);signals:void disconn(qintptr socketDescriptor);void activeconn(qintptr socketDescriptor);
public slots:void disconnectedToHost();void recvMsg();
private:qintptr m_socketDescriptor;
};#endif // SESSION_H

4.session.cpp

#include"session.h"
#include<QtNetwork/QHostAddress>
#include <QTextCodec>Session::Session(qintptr socketDescriptor):m_socketDescriptor(socketDescriptor)
{qRegisterMetaType<qintptr>("qintptr");this->setSocketDescriptor(m_socketDescriptor);connect(this, &QTcpSocket::readyRead, this, &Session::recvMsg);connect(this, &QTcpSocket::disconnected, this, &Session::disconnectedToHost);
}Session::~Session()
{}void Session::sendMsg(const QString msg)
{this->write(msg.toUtf8());
}void Session::disconnectedToHost()
{QString ip = this->peerAddress().toString();qDebug()<<QString("客户端%1:%2断开连接").arg(ip).arg(this->peerPort());this->close();emit disconn(m_socketDescriptor);
}void Session::recvMsg()
{emit activeconn(m_socketDescriptor);QByteArray msg;msg.append(this->readAll());while(this->bytesAvailable()>0){this->waitForReadyRead(10);msg.append(this->readAll());}QTextCodec *codec = QTextCodec::codecForName("GBK");QString data = codec->toUnicode(msg);qDebug()<<data;
}

5.main.cpp

#include <QCoreApplication>
#include "tcpserver.h"int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);TcpServer tcps;return a.exec();
}

通过以上步骤，开发者可快速构建一个稳定高效的Qt TCP服务端，实际项目中需根据业务需求扩展身份验证、数据加密等功能。Qt的异步编程模型与丰富的网络API，使其成为开发跨平台网络应用的理想选择。
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