写一个reactor处理http请求的代码

以下是一个简单的 Reactor 模式的 HTTP 服务器示例代码，使用 C++11 和 Boost.Asio 库实现：

#include <iostream>
#include <boost/asio.hpp>

using namespace boost::asio;
using namespace boost::asio::ip;

class HttpRequest {
public:
    HttpRequest() {}

    std::string method;
    std::string uri;
    std::string version;
};

class HttpResponse {
public:
    HttpResponse() {}

    std::string version;
    std::string status;
    std::string reason;
    std::string content;
};

class HttpServer {
public:
    HttpServer(io_service& io_service, short port)
        : acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
        , socket_(io_service) {
        do_accept();
    }

private:
    void do_accept() {
        acceptor_.async_accept(socket_, [this](boost::system::error_code ec) {
            if (!ec) {
                std::make_shared<HttpSession>(std::move(socket_))->start();
            }

            do_accept();
        });
    }

    tcp::acceptor acceptor_;
    tcp::socket socket_;
};

class HttpSession : public std::enable_shared_from_this<HttpSession> {
public:
    HttpSession(tcp::socket socket)
        : socket_(std::move(socket)) {}

    void start() {
        do_read();
    }

private:
    void do_read() {
        auto self(shared_from_this());
        socket_.async_read_some(buffer(buffer_), [this, self](boost::system::error_code ec, std::size_t length) {
            if (!ec) {
                std::string request_str(buffer_.data(), length);
                HttpRequest request = parse_request(request_str);

                HttpResponse response;
                response.version = "HTTP/1.1";
                response.status = "200";
                response.reason = "OK";
                response.content = "Hello, World!";

                std::string response_str = build_response(response);
                do_write(response_str);
            }
        });
    }

    void do_write(std::string response_str) {
        auto self(shared_from_this());
        async_write(socket_, buffer(response_str), [this, self](boost::system::error_code ec, std::size_t length) {
            if (!ec) {
                socket_.shutdown(tcp::socket::shutdown_both, ec);
            }
        });
    }

    HttpRequest parse_request(std::string request_str) {
        HttpRequest request;
        std::istringstream iss(request_str);
        iss >> request.method >> request.uri >> request.version;
        return request;
    }

    std::string build_response(HttpResponse response) {
        std::ostringstream oss;
        oss << response.version << " " << response.status << " " << response.reason << "\r\n";
        oss << "Content-Type: text/plain\r\n";
        oss << "Content-Length: " << response.content.size() << "\r\n";
        oss << "\r\n";
        oss << response.content;
        return oss.str();
    }

    tcp::socket socket_;
    boost::array<char, 8192> buffer_;
};

int main(int argc, char* argv[]) {
    try {
        if (argc != 2) {
            std::cerr << "Usage: http_server <port>\n";
            return 1;
        }

        io_service io_service;
        HttpServer server(io_service, std::atoi(argv[1]));
        io_service.run();
    }
    catch (std::exception& e) {
        std::cerr << "Exception: " << e.what() << "\n";
    }

    return 0;
}

这个代码使用 Boost.Asio 库实现了一个简单的 HTTP 服务器。它使用 Reactor 模式处理客户端连接，并在客户端连接时创建一个 HttpSession 对象来处理客户端请求。在 HttpSession 对象中，它使用 async_read_some 和 async_write 异步操作来读取客户端请求并向客户端发送响应。在这个示例中，它只是简单地返回一个 "Hello, World!" 消息。