qt QWebSocketServer详解

1、概述

QWebSocketServer 是 Qt 框架中用于处理 WebSocket 服务器端的类。它允许开发者创建 WebSocket 服务器，接受客户端的连接，并与之进行双向通信。WebSocket 是一种在单个 TCP 连接上进行全双工通讯的协议，它使得客户端和服务器之间的数据交换变得更加简单和高效。

QWebSocketServer 提供了 WebSocket 服务器所需的基本功能，包括监听端口、接受连接、发送和接收消息等。它通常与 QWebSocket 类一起使用，后者表示一个 WebSocket 连接，并提供了与该连接进行交互的方法。

2、重要方法

QWebSocketServer 类的重要方法包括但不限于：

QWebSocketServer(const QString &serverName, QWebSocketServer::NonSecureMode serverType = NonSecureMode, QObject *parent = nullptr): 构造函数，创建一个 WebSocket 服务器实例。
bool listen(const QHostAddress &address = QHostAddress::Any, quint16 port = 0): 使服务器监听指定的地址和端口。
void close(): 关闭服务器，停止监听连接。
QList<QWebSocket *> clients() const: 返回当前连接到服务器的所有客户端列表。
bool hasPendingConnections() const: 检查是否有等待接受的连接。
QWebSocket *nextPendingConnection(): 接受一个等待中的连接，并返回一个新的 QWebSocket 对象来表示该连接。
QString serverName() const: 返回服务器的名称。
QWebSocketServer::WebSocketServerState state() const: 返回服务器的当前状态（如监听中、关闭等）。

3、重要信号

QWebSocketServer 类的重要信号包括：

newConnection(): 当有新的客户端连接请求时发出。
acceptError(QAbstractSocket::SocketErrors socketError):当连接出现错误时发出信号。
serverError(0WebSocketProtocol::CloseCode closeCode):当服务器发生错误时发出信号。

4、常用枚举类型

以下是 QWebSocketServer类中一些常用的枚举类型及其简要介绍：
QWebSocketServer::SslMode: SSL 模式。

SslMode::NonSecureMode:不支持SSL/TLS
SslMode::SecureMode:支持SSL/TLS

5、实现 SSL/TLS 加密
QWebSocketServer 支持 SSL/TLS 加密以提供安全的WebSocket 连接。为了实现SSL/TLS，您需要配置合适的证书和密钥：

QWebSocketServer server("Secure WebSocket Server", QWebSocketServer::SecureMode);
QSslConfiguration sslConfiguration;
sslConfiguration.setLocalCertificate(QStringLiteral("server.crt"));
sslConfiguration.setPrivateKey(QStringLiteral("server.key"));
server.setSslConfiguration(sslConfiguration);

if (server.listen(QHostAddress::Any, 1234)) {
qDebug() << "Secure WebSocket server listening on port 1234.";
}

//.h
class MyWebSocketClient : public QObject {Q_OBJECTpublic:MyWebSocketClient(QObject *parent = nullptr) : QObject(parent), m_pWebSocket(nullptr) {m_pWebSocket = new QWebSocket();// 连接服务器QUrl serverUrl("ws://localhost:12345"); // 替换为实际的服务器URLm_pWebSocket->open(serverUrl);// 连接信号和槽connect(m_pWebSocket, &QWebSocket::connected, this, &MyWebSocketClient::onConnected);connect(m_pWebSocket, &QWebSocket::disconnected, this, &MyWebSocketClient::onDisconnected);connect(m_pWebSocket, QOverload<QAbstractSocket::SocketError>::of(&QWebSocket::error), this, &MyWebSocketClient::onError);connect(m_pWebSocket, &QWebSocket::textMessageReceived, this, &MyWebSocketClient::onTextMessageReceived);}~MyWebSocketClient() {m_pWebSocket->close();}private slots:void onConnected() {qDebug() << "Connected to WebSocket server";// 发送消息给服务器QString message = "Hello, WebSocket server!";m_pWebSocket->sendTextMessage(message);}void onDisconnected() {qDebug() << "Disconnected from WebSocket server";}void onError(QAbstractSocket::SocketError error) {qDebug() << "WebSocket error:" << error;}void onTextMessageReceived(QString message) {qDebug() << "Received message from WebSocket server:" << message;}private:QWebSocket *m_pWebSocket;
};class WebSocketServer : public QObject
{Q_OBJECTpublic:explicit WebSocketServer(quint16 port=12345, QObject *parent = nullptr);~WebSocketServer();private slots:void onNewConnection();void onTextMessageReceived(const QString &message);void onDisconnected();private:QWebSocketServer *m_server;QList<QWebSocket *> m_clients;
};/************************************/
//.cpp
WebSocketServer::WebSocketServer(quint16 port, QObject *parent): QObject(parent),m_server(new QWebSocketServer(QStringLiteral("WebSocket Server"), QWebSocketServer::NonSecureMode, this))
{if (m_server->listen(QHostAddress::Any, port)) {qDebug() << "WebSocket server listening on port" << port;connect(m_server, &QWebSocketServer::newConnection, this, &WebSocketServer::onNewConnection);} else {qDebug() << "Error: Unable to start the WebSocket server:" << m_server->errorString();}
}WebSocketServer::~WebSocketServer()
{m_server->close();qDeleteAll(m_clients.begin(), m_clients.end());
}void WebSocketServer::onNewConnection()
{QWebSocket *client = m_server->nextPendingConnection();connect(client, &QWebSocket::textMessageReceived, this, &WebSocketServer::onTextMessageReceived);connect(client, &QWebSocket::disconnected, this, &WebSocketServer::onDisconnected);m_clients << client;qDebug() << "New client connected.";
}void WebSocketServer::onTextMessageReceived(const QString &message)
{QWebSocket *client = qobject_cast<QWebSocket *>(sender());qDebug() << "Message received:" << message;client->sendTextMessage("Echo: " + message);
}void WebSocketServer::onDisconnected()
{QWebSocket *client = qobject_cast<QWebSocket *>(sender());if (client) {m_clients.removeAll(client);client->deleteLater();qDebug() << "Client disconnected.";}
}