本文标题:QTcpServer实现多客户端连接 本文地址:http://techieliang.com/2017/12/760/
1. 介绍
QTcpServer使用请见:QTcpSocket-Qt使用Tcp通讯实现服务端和客户端
QTcpServer类默认提供的只有无参数的newConnection的信号,这样虽然知道有人连接了,并且可以通过nextPendingConnection获取连接的socket,但并不便于管理,尤其是在连接断开以后无法判断具体那个断开了,因为QTcpSocket只提供了无参的disconnected信号。。。
这样就算在newConnection是存储一个list或者map,也无法在disconnected是知道具体是那一项断开连接,给不同的QTcpSocket的信号指向不同的槽。
实际上socket有自己的句柄,并通过下述函数在初步连接时就赋予了对应的socketDescriptor
- virtual void incomingConnection(qintptr socketDescriptor)
当有client连接时,首先是此方法被调用,可自行在此方法内建立QTcpSocket并将socketDescriptor值赋予socket,并在socket断开时告知此标识符
2. 范例
源码请见GitHub:QtOtherModuleExamples
tcp_server.h
- #ifndef TCP_SERVER_H
- #define TCP_SERVER_H
- #include <QTcpServer>
- namespace tcp_server_private {
- class TcpServerPrivate;
- }
- class QTcpSocket;
- /**
- * @brief Tcp多客户端服务器
- */
- class TcpServer : public QTcpServer {
- Q_OBJECT
- public:
- /**
- * @brief 构造函数
- * @param parent 父QObject
- */
- explicit TcpServer(QObject *parent = Q_NULLPTR);
- /**
- * @brief 析构函数
- * 非多线程模式行为:关闭所有连接后析构
- * 多线程模式行为:关闭所有连接及线程池后析构
- */
- ~TcpServer();
- signals:
- /**
- * @brief 客户端连入
- * @param 连接句柄
- * @param socket指针
- */
- void ClientConnected(qintptr, QTcpSocket*);//发送新用户连接信息
- /**
- * @brief socket已断开连接
- * 若需要在socket后析构后进行操作的可连接此信号
- * @param 连接句柄
- */
- void ClientDisconnected(qintptr);
- /**
- * @brief 主动断开连接信号
- * 若服务端想要主动断开与客户端连接将会发出此信号
- * 此信号发出这表明进行断开操作不表明断开成功,成功以SocketDisconnected信号为准
- * @param 连接句柄
- */
- void InitiativeDisConnectClient(qintptr);
- protected slots:
- /**
- * @brief 客户端已断开槽
- * 此槽与客户端的已断开信号连接
- * @param handle
- */
- void ClientDisconnectedSlot(qintptr handle);
- protected:
- /**
- * @brief 重写-有连接到来
- * 连接到来不一定连接,会根据maxPendingConnections决定是否连接
- * @param handle 连接句柄
- */
- virtual void incomingConnection(qintptr handle);
- private:
- tcp_server_private::TcpServerPrivate *private_;
- };
- #endif // TCP_SERVER_H
tcp_server.cpp
- #include "tcp_server.h"
- #include "tcp_server_private.h"
- //构造函数
- TcpServer::TcpServer(QObject *parent)
- : QTcpServer(parent),
- private_(new tcp_server_private::TcpServerPrivate) {
- }
- //析构函数
- TcpServer::~TcpServer() {
- for(tcp_server_private::TcpSocket *client : private_->clients.values()) {
- client->disconnectFromHost();
- auto handle = client->socketDescriptor();
- client->deleteLater();
- //告知其他调用者 当前socket断开,避免有需要在socket后执行的方法
- emit ClientDisconnected(handle);
- }
- if(private_)
- delete private_;
- this->close();
- }
- //重写-有连接到来
- void TcpServer::incomingConnection(qintptr handle) {
- //超出最大练级数量关闭连接
- if (private_->clients.size() > maxPendingConnections()) {
- QTcpSocket tcp;
- tcp.setSocketDescriptor(handle);
- tcp.disconnectFromHost();
- return;
- }
- auto client_socket = new tcp_server_private::TcpSocket(handle);
- Q_ASSERT(client_socket->socketDescriptor() == handle);
- //socket断开连接的信号与server槽连接
- connect(client_socket,
- &tcp_server_private::TcpSocket::ClientDisconnected,
- this,
- &TcpServer::ClientDisconnectedSlot);
- //主动断开连接的操作
- connect(this,
- &TcpServer::InitiativeDisConnectClient,
- client_socket,
- &tcp_server_private::TcpSocket::DisconnectSocket);
- //map记录
- private_->clients.insert(handle, client_socket);
- qDebug()<<handle<<"connected";
- emit ClientConnected(handle, client_socket);
- }
- //客户端已断开槽
- void TcpServer::ClientDisconnectedSlot(qintptr handle) {
- //map中移除
- private_->clients.remove(handle);
- qDebug()<<handle<<"disconnected";
- //发出信号
- emit ClientDisconnected(handle);
- }
private
- #ifndef TCP_SERVER_PRIVATE_H
- #define TCP_SERVER_PRIVATE_H
- #include <QTcpSocket>
- namespace tcp_server_private {
- class TcpSocket : public QTcpSocket {
- Q_OBJECT
- public:
- /**
- * @brief 构造函数
- * @param socketDescriptor 连接句柄
- * @param parent 父QObject
- */
- TcpSocket(qintptr handle, QObject *parent = 0);
- signals:
- /*
- * 已断开连接信号
- */
- void ClientDisconnected(qintptr);
- public slots:
- /**
- * @brief 断开连接
- * @param handle 连接句柄
- */
- void DisconnectSocket(qintptr handle);
- private:
- qintptr handle_;
- };
- /**
- * @brief Tcp多客户端服务器私有类
- */
- class TcpServerPrivate {
- public:
- QMap<int, TcpSocket *> clients; ///所有连接的map
- };
- }//tcp_server_private
- #endif // TCP_SERVER_PRIVATE_H
- //cpp
- #include "tcp_server_private.h"
- namespace tcp_server_private {
- //构造函数
- TcpSocket::TcpSocket(qintptr handle, QObject *parent)
- : QTcpSocket(parent), handle_(handle) {
- this->setSocketDescriptor(handle_);
- //断开连接消息
- connect(this,&TcpSocket::disconnected,
- [&](){
- this->deleteLater();
- emit this->ClientDisconnected(handle_);
- });
- }
- //主动断开连接槽
- void TcpSocket::DisconnectSocket(qintptr handle) {
- if (handle == handle_)
- disconnectFromHost();
- }
- }
- incomingConnection首先判断是否超出最大连接数量,超出就断开新链接,最大连接数量在maxPendingConnections方法获取,而当前已连接client在自定义server的TcpServerPrivate::clients这个QMap记录,此map记录了socketDescriptor和socket指针的映射关系
- 若未达最大连接数量,则连接创建新的tcpsocket,并将socketDescriptor赋值到socket对象,最后发出ClientConnected信号,此信号带有新链接的socket的指针,可以用于自定义收发信号槽。
- socket对象的disconnected信号直接connect到了lambda表达式以发出新的信号,新信号ClientDisconnected,并带有socketDescriptor句柄标识符,从而避免了socket断开连接后不知道具体哪个断开
- socket在创建时均吧ClientDisconnected信号与server的ClientDisconnectedSlot槽连接,当有连接断开时会动态维护map记录
- server析构时以disconnectFromHost方法主动断开和所有客户端连接,若需要等客户端先断开可以用waitForDisconnected
上述范例将TcpSocket定义在tcp_server_private命名空间不对外可见,且TcpServer返回值也是QTcpSocket,若需要继承QTcpSocket做更多自定义需要将TcpSocket移出