C++ WebSocket庫與WebSocket客戶端的自動重連

在C++中，有幾個流行的WebSocket庫可以用于實現WebSocket客戶端和服務器

1. 使用websocketpp庫：

websocketpp是一個高性能的C++ WebSocket庫，支持Boost.Asio庫。要實現自動重連，你需要在連接斷開時捕獲相應的事件，并在適當的時候嘗試重新連接。

首先，安裝websocketpp庫：

git clone https://github.com/zaphoyd/websocketpp.git
cd websocketpp
mkdir build
cd build
cmake ..
make install

然后，創建一個名為websocket_client.cpp的文件，包含以下內容：

#include<iostream>
#include <websocketpp/config/asio_no_tls_client.hpp>
#include <websocketpp/client.hpp>

typedef websocketpp::client<websocketpp::config::asio_client> client;

using websocketpp::lib::placeholders::_1;
using websocketpp::lib::placeholders::_2;
using websocketpp::lib::bind;

class WebSocketClient {
public:
    WebSocketClient() : m_reconnecting(false) {
        m_client.clear_access_channels(websocketpp::log::alevel::all);
        m_client.clear_error_channels(websocketpp::log::elevel::all);

        m_client.init_asio();

        m_client.set_open_handler(bind(&WebSocketClient::on_open, this, _1));
        m_client.set_close_handler(bind(&WebSocketClient::on_close, this, _1));
        m_client.set_fail_handler(bind(&WebSocketClient::on_fail, this, _1));
    }

    void connect(const std::string &uri) {
        websocketpp::lib::error_code ec;
        client::connection_ptr con = m_client.get_connection(uri, ec);
        if (ec) {
            std::cout << "Could not create connection: " << ec.message()<< std::endl;
            return;
        }

        m_client.connect(con);
    }

    void run() {
        m_client.run();
    }

private:
    void on_open(websocketpp::connection_hdl hdl) {
        std::cout << "Connected to server"<< std::endl;
        m_reconnecting = false;
    }

    void on_close(websocketpp::connection_hdl hdl) {
        std::cout << "Connection closed"<< std::endl;
        if (!m_reconnecting) {
            m_reconnecting = true;
            m_client.get_io_service().post(bind(&WebSocketClient::reconnect, this));
        }
    }

    void on_fail(websocketpp::connection_hdl hdl) {
        std::cout << "Connection failed"<< std::endl;
        if (!m_reconnecting) {
            m_reconnecting = true;
            m_client.get_io_service().post(bind(&WebSocketClient::reconnect, this));
        }
    }

    void reconnect() {
        std::cout << "Reconnecting..."<< std::endl;
        connect("ws://your-websocket-server-uri");
    }

    client m_client;
    bool m_reconnecting;
};

int main() {
    WebSocketClient client;
    client.connect("ws://your-websocket-server-uri");
    client.run();

    return 0;
}

編譯并運行示例：

g++ websocket_client.cpp -o websocket_client -lwebsocketpp -lpthread -lboost_system
./websocket_client

這個示例將連接到指定的WebSocket服務器，并在連接斷開時嘗試自動重連。請確保將your-websocket-server-uri替換為實際的WebSocket服務器URI。