简介：

前面的几篇文章已经介绍了如何使用asio搭建高并发的tcp服务器，以及http服务器。但是纯手写http服务器太麻烦了，有网络库beast已经帮我们实现了。这一期讲讲如何使用beast实现一个http服务器。

连接类

我们先实现http_server函数

void http_server(tcp::acceptor& acceptor, tcp::socket& socket)
{
    acceptor.async_accept(socket,
    [&](beast::error_code ec)
    {
    if (!ec)
        std::make_shared<http_connection>(std::move(socket))->start();
        http_server(acceptor, socket);
    });
}

http_server中添加了异步接收连接的逻辑，当有新的连接到来时创建，然后启动服务，新连接监听对端数据。接下来http_server继续监听对端的新连接。
连接类里实现了start函数监听对端数据http_connection``http_connection

void start()
{
    read_request();
    check_deadline();
}

处理读请求,将读到的数据存储再成员变量中，然后调用处理请求request_``process_request

void read_request()
{
    auto self = shared_from_this();
    http::async_read(
        socket_,
        buffer_,
        request_,
        [self](beast::error_code ec,
                std::size_t bytes_transferred)
        {
            boost::ignore_unused(bytes_transferred);
            if (!ec)
                self->process_request();
        });
}

check_deadline主要时用来检测超时，当超过一定时间后自动关闭连接，因为http请求时短链接

void check_deadline()
{
    auto self = shared_from_this();
    deadline_.async_wait(
    [self](beast::error_code ec)
    {
        if (!ec)
        {
            // Close socket to cancel any outstanding operation.
            self->socket_.close(ec);
        }
    });
}

process_request函数中区分请求的类型，进行不同类型的处理如post还是get请求

void process_request()
{
    response_.version(request_.version());
    response_.keep_alive(false);
    switch (request_.method())
    {
    case http::verb::get:
        response_.result(http::status::ok);
        response_.set(http::field::server, "Beast");
        create_response();
        break;
    case http::verb::post:
        response_.result(http::status::ok);
        response_.set(http::field::server, "Beast");
        create_post_response();
        break;
    default:
        // We return responses indicating an error if
        // we do not recognize the request method.
        response_.result(http::status::bad_request);
        response_.set(http::field::content_type, "text/plain");
        beast::ostream(response_.body())
        << "Invalid request-method '"
        << std::string(request_.method_string())
        << "'";
        break;
    }
    write_response();
}

create_response函数中解析了不同的路由处理get请求

void create_response()
{
    if (request_.target() == "/count")
    {
        response_.set(http::field::content_type, "text/html");
        beast::ostream(response_.body())
        << "<html>\n"
        << "<head><title>Request count</title></head>\n"
        << "<body>\n"
        << "<h1>Request count</h1>\n"
        << "<p>There have been "
        << my_program_state::request_count()
        << " requests so far.</p>\n"
        << "</body>\n"
        << "</html>\n";
    }
    else if (request_.target() == "/time")
    {
        response_.set(http::field::content_type, "text/html");
        beast::ostream(response_.body())
        << "<html>\n"
        << "<head><title>Current time</title></head>\n"
        << "<body>\n"
        << "<h1>Current time</h1>\n"
        << "<p>The current time is "
        << my_program_state::now()
        << " seconds since the epoch.</p>\n"
        << "</body>\n"
        << "</html>\n";
    }
    else
    {
        response_.result(http::status::not_found);
        response_.set(http::field::content_type, "text/plain");
        beast::ostream(response_.body()) << "File not found\r\n";
    }
}

create_post_response处理了post请求中的一部分路由

void create_post_response() {
    if (request_.target() == "/email")
    {
        auto& body = this->request_.body();
        auto body_str = boost::beast::buffers_to_string(body.data());
        std::cout << "receive body is " << body_str << std::endl;
        this->response_.set(http::field::content_type, "text/json");
        Json::Value root;
        Json::Reader reader;
        Json::Value src_root;
        bool parse_success = reader.parse(body_str, src_root);
    if (!parse_success) {
        std::cout << "Failed to parse JSON data!" << std::endl;
        root["error"] = 1001;
        std::string jsonstr = root.toStyledString();
        beast::ostream(this->response_.body()) << jsonstr;
        return ;
    }
    auto email = src_root["email"].asString();
    std::cout << "email is " << email << std::endl;
    root["error"] = 0;
    root["email"] = src_root["email"];
    root["msg"] = "recevie email post success";
    std::string jsonstr = root.toStyledString();
    beast::ostream(this->response_.body()) << jsonstr;
    }
    else
    {
        response_.result(http::status::not_found);
        response_.set(http::field::content_type, "text/plain");
        beast::ostream(response_.body()) << "File not found\r\n";
    }
}

write_response发送请求

void write_response()
{
    auto self = shared_from_this();
    response_.content_length(response_.body().size());
    http::async_write(
        socket_,
        response_,
        [self](beast::error_code ec, std::size_t)
        {
            self->socket_.shutdown(tcp::socket::shutdown_send, ec);
            self->deadline_.cancel();
        });
}

beast::网络库搭建http服务器

简介：

连接类