【c++从http后端拿数据的demo】

c++从http后端拿数据的demo

从http后端拿数据,并用nlohmann解析数据
main.cpp

#include <boost/asio/connect.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <fstream>
#include <iostream>
#include <nlohmann/json.hpp>


using json = nlohmann::json;

int main() {
    auto host = "127.0.0.1";
    auto port = "3000";
    //    auto target = "/task/record/fetch_data/test_task?page=6&page_size=1";
    for (int i = 0; i < 10; i++) {
        std::stringstream url_stream;
        url_stream << "/task/record/fetch_data/test_task?page=" << i << "&page_size=1";
        auto target = url_stream.str();

        namespace beast = boost::beast;// from <boost/beast.hpp>
        namespace http = beast::http;  // from <boost/beast/http.hpp>
        namespace net = boost::asio;   // from <boost/asio.hpp>
        using tcp = net::ip::tcp;      // from <boost/asio/ip/tcp.hpp>
        // The io_context is required for all I/O
        net::io_context ioc;

        // These objects perform our I/O
        tcp::resolver resolver(ioc);
        beast::tcp_stream stream(ioc);

        // Look up the domain name
        auto const results = resolver.resolve(host, port);

        // Make the connection on the IP address we get from a lookup
        stream.connect(results);

        // Set up an HTTP GET request message
        http::request<http::string_body> req{http::verb::get, target, 11};
        req.set(http::field::host, host);
        req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);

        // Send the HTTP request to the remote host
        http::write(stream, req);

        // This buffer is used for reading and must be persisted
        beast::flat_buffer buffer;

        // Declare a container to hold the response
        http::response<http::string_body> res;

        // Receive the HTTP response
        http::read(stream, buffer, res);

        //        std::cout << res.body().c_str() << std::endl;

        // Gracefully close the socket
        beast::error_code ec;
        stream.socket().shutdown(tcp::socket::shutdown_both, ec);

        // not_connected happens sometimes
        // so don't bother reporting it.
        //
        if (ec && ec != beast::errc::not_connected) {
            std::terminate();
        }


        //    auto f =  std::ifstream("/home/hello/下载/response_1697094387779.json");
        //
        //    std::stringstream  ss;
        //    ss << f.rdbuf();
        //
        //    std::cout << ss.str() << std::endl;

        std::string json_str = res.body().c_str();
        json j = json::parse(json_str);


        std::cout << j.dump() << std::endl;
    }
    return 0;
}

cmakelists

cmake_minimum_required(VERSION 3.26)
project(test_js)

set(CMAKE_CXX_STANDARD 17)

find_package(nlohmann_json)
find_package(Boost REQUIRED)

add_executable(test_js main.cpp)

target_link_libraries(test_js
        ${Boost_LIBRARIES}
        nlohmann_json::nlohmann_json)

tip：
安装nlohmann json

git clone https://github.com/nlohmann/json.git //也可以自己手动下载解压到合适的文件夹下
cd json
mkdir build
cd build/
cmake ..
make
make install

部分命令可能要用sudo进行执行