C++实现轻量级极简httpserver和httpclient(转)

一般来说，C++的项目多是偏底层，不怎么需要跟http打交道，但有时候又需要在C++后端项目中加入一些简单 http接口，比如游戏运营服务器，金融交易监控服务等。

但是传统的实现方法比如采用libcurl，asio等较为重型的框架来做有没有必要，因此，这里采用mongoose这个库来实现基本的httpserver和httpclient功能，非常简单，包含一个h文件，一个cpp文件到工程中就行了，无需编译，无需链接库。

本文实现了一个project，将mongoose中提供的http相关api封装成了httpserver类和httpclient类，方便调用，目录结构如下：

├─common
    ├─mongoose.h
    └─mongoose.cpp
├─httpclient
    ├─http_client.h
    ├─http_client.cpp
    └─main.cpp
└─httpserver
    └─web
       └─index.html
    ├─http_server.h
    ├─http_server.cpp
    └─main.cpp

编译环境：win10，vs2015， C++11 （其实是跨平台的）

http_server.h

#pragma once
#include
#include
#include
#include "../common/mongoose.h"

// 定义http返回callback
typedef void OnRspCallback(mg_connection *c, std::string);
// 定义http请求handler
using ReqHandler = std::function;

class HttpServer
{
public:
    HttpServer() {}
    ~HttpServer() {}
    void Init(const std::string &port); // 初始化设置
    bool Start(); // 启动httpserver
    bool Close(); // 关闭
    void AddHandler(const std::string &url, ReqHandler req_handler); // 注册事件处理函数
    void RemoveHandler(const std::string &url); // 移除时间处理函数
    static std::string s_web_dir; // 网页根目录 
    static mg_serve_http_opts s_server_option; // web服务器选项
    static std::unordered_map s_handler_map; // 回调函数映射表

private:
    // 静态事件响应函数
    static void OnHttpEvent(mg_connection *connection, int event_type, void *event_data);
    static void HandleEvent(mg_connection *connection, http_message *http_req);
    static void SendRsp(mg_connection *connection, std::string rsp);

    std::string m_port;    // 端口
    mg_mgr m_mgr;          // 连接管理器
};

http_server.cpp

#include
#include "http_server.h"

void HttpServer::Init(const std::string &port)
{
    m_port = port;
    s_server_option.enable_directory_listing = "yes";
    s_server_option.document_root = s_web_dir.c_str();
    // TODO：其他设置
}

bool HttpServer::Start()
{
    mg_mgr_init(&m_mgr, NULL);
    mg_connection *connection = mg_bind(&m_mgr, m_port.c_str(), OnHttpEvent);
    if (connection == NULL)
        return false;
    mg_set_protocol_http_websocket(connection);

    printf("starting http server at port: %s\n", m_port.c_str());
    // loop
    while (true)
        mg_mgr_poll(&m_mgr, 500); // ms

    return true;
}

void HttpServer::OnHttpEvent(mg_connection *connection, int event_type, void *event_data)
{
    http_message *http_req = (http_message *)event_data;
    switch (event_type)
    {
    case MG_EV_HTTP_REQUEST:
        HandleEvent(connection, http_req);
        break;
    default:
        break;
    }
}

static bool route_check(http_message *http_msg, char *route_prefix)
{
    if (mg_vcmp(&http_msg->uri, route_prefix) == 0)
        return true;
    else
        return false;

    // TODO: 还可以判断 GET, POST, PUT, DELTE等方法
    //mg_vcmp(&http_msg->method, "GET");
    //mg_vcmp(&http_msg->method, "POST");
    //mg_vcmp(&http_msg->method, "PUT");
    //mg_vcmp(&http_msg->method, "DELETE");
}

void HttpServer::AddHandler(const std::string &url, ReqHandler req_handler)
{
    if (s_handler_map.find(url) != s_handler_map.end())
        return;

    s_handler_map.insert(std::make_pair(url, req_handler));
}

void HttpServer::RemoveHandler(const std::string &url)
{
    auto it = s_handler_map.find(url);
    if (it != s_handler_map.end())
        s_handler_map.erase(it);
}

void HttpServer::SendRsp(mg_connection *connection, std::string rsp)
{
    // 必须先发送header
    mg_printf(connection, "%s", "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n");
    // 以json形式返回
    mg_printf_http_chunk(connection, "{ \"result\": %s }", rsp.c_str());
    // 发送空白字符快，结束当前响应
    mg_send_http_chunk(connection, "", 0);
}

void HttpServer::HandleEvent(mg_connection *connection, http_message *http_req)
{
    std::string req_str = std::string(http_req->message.p, http_req->message.len);
    printf("got request: %s\n", req_str.c_str());

    // 先过滤是否已注册的函数回调
    std::string url = std::string(http_req->uri.p, http_req->uri.len);
    std::string body = std::string(http_req->body.p, http_req->body.len);
    auto it = s_handler_map.find(url);
    if (it != s_handler_map.end())
    {
        ReqHandler handle_func = it->second;
        handle_func(url, body, connection, SendRsp);
    }

    // 其他请求
    if (route_check(http_req, "/")) // index page
        mg_serve_http(connection, http_req, s_server_option);
    else if (route_check(http_req, "/api/hello")) 
    {
        // 直接回传
        SendRsp(connection, "welcome to httpserver");
    }
    else if (route_check(http_req, "/api/sum"))
    {
        // 简单post请求，加法运算测试
        char n1[100], n2[100];
        double result;

        /* Get form variables */
        mg_get_http_var(&http_req->body, "n1", n1, sizeof(n1));
        mg_get_http_var(&http_req->body, "n2", n2, sizeof(n2));

        /* Compute the result and send it back as a JSON object */
        result = strtod(n1, NULL) + strtod(n2, NULL);
        SendRsp(connection, std::to_string(result));
    }
    else
    {
        mg_printf(
            connection,
            "%s",
            "HTTP/1.1 501 Not Implemented\r\n"
            "Content-Length: 0\r\n\r\n");
    }
}

bool HttpServer::Close()
{
    mg_mgr_free(&m_mgr);
    return true;
}

index.html

 

   

c++ httpserver demo

   

      front end request
   

   

GET

   

        get request
   

   

     Result1:
   

   

POST

   

      Number 1:
   

   

      Number 2:
   

   

     Result2:
   

 

main.cpp

#include
#include
#include "http_server.h"

// 初始化HttpServer静态类成员
mg_serve_http_opts HttpServer::s_server_option;
std::string HttpServer::s_web_dir = "./web";
std::unordered_map HttpServer::s_handler_map;

bool handle_fun1(std::string url, std::string body, mg_connection *c, OnRspCallback rsp_callback)
{
    // do sth
    std::cout << "handle fun1" << std::endl;
    std::cout << "url: " << url << std::endl;
    std::cout << "body: " << body << std::endl;

    rsp_callback(c, "rsp1");

    return true;
}

bool handle_fun2(std::string url, std::string body, mg_connection *c, OnRspCallback rsp_callback)
{
    // do sth
    std::cout << "handle fun2" << std::endl;
    std::cout << "url: " << url << std::endl;
    std::cout << "body: " << body << std::endl;

    rsp_callback(c, "rsp2");

    return true;
}

int main(int argc, char *argv[]) 
{
    std::string port = "7999";
    auto http_server = std::shared_ptr(new HttpServer);
    http_server->Init(port);
    // add handler
    http_server->AddHandler("/api/fun1", handle_fun1);
    http_server->AddHandler("/api/fun2", handle_fun2);
    http_server->RemoveHandler("/api/fun3");
    // http_server->RemoveHandler("/api/fun3");
    http_server->Start();
    
    return 0;
}

服务器支持host静态页面资源，也支持rest api调用
需要手动设置loop polling的时间间隔
可以自定义静态页面根路径，注册和解注册自定义api函数回调
某些变量必须声明定义成全局或者静态变量

http客户端

http_client.h

#pragma once
#include
#include
#include "../common/mongoose.h"

// 此处必须用function类，typedef再后面函数指针赋值无效
using ReqCallback = std::function;

class HttpClient
{
public:
    HttpClient() {}
    ~HttpClient() {}

    static void SendReq(const std::string &url, ReqCallback req_callback);
    static void OnHttpEvent(mg_connection *connection, int event_type, void *event_data);
    static int s_exit_flag;
    static ReqCallback s_req_callback;
};

http_client.cpp

#include "http_client.h"

// 初始化client静态变量
int HttpClient::s_exit_flag = 0;
ReqCallback HttpClient::s_req_callback;

// 客户端的网络请求响应
void HttpClient::OnHttpEvent(mg_connection *connection, int event_type, void *event_data)
{
    http_message *hm = (struct http_message *)event_data;
    int connect_status;

    switch (event_type) 
    {
    case MG_EV_CONNECT:
        connect_status = *(int *)event_data;
        if (connect_status != 0) 
        {
            printf("Error connecting to server, error code: %d\n", connect_status);
            s_exit_flag = 1;
        }
        break;
    case MG_EV_HTTP_REPLY:
    {
        printf("Got reply:\n%.*s\n", (int)hm->body.len, hm->body.p);
        std::string rsp = std::string(hm->body.p, hm->body.len);
        connection->flags |= MG_F_SEND_AND_CLOSE;
        s_exit_flag = 1; // 每次收到请求后关闭本次连接，重置标记
        
        // 回调处理
        s_req_callback(rsp);
    }
        break;
    case MG_EV_CLOSE:
        if (s_exit_flag == 0) 
        {
            printf("Server closed connection\n");
            s_exit_flag = 1;
        };
        break;
    default:
        break;
    }
}

// 发送一次请求，并回调处理，然后关闭本次连接
void HttpClient::SendReq(const std::string &url, ReqCallback req_callback)
{
    // 给回调函数赋值
    s_req_callback = req_callback;
    mg_mgr mgr;
    mg_mgr_init(&mgr, NULL);
    auto connection = mg_connect_http(&mgr, OnHttpEvent, url.c_str(), NULL, NULL);
    mg_set_protocol_http_websocket(connection);

    printf("Send http request %s\n", url.c_str());

    // loop
    while (s_exit_flag == 0)
        mg_mgr_poll(&mgr, 500);

    mg_mgr_free(&mgr);
}

client每次请求都是一个独立的请求
请求函数中加入回调用于处理网络返回

测试
可以用浏览器、或者其他工具提交url，查看网络请求返回
GET请求 
http://localhost:7999/api/hello

结果
{ "result": welcome to httpserver }

POST请求
http://localhost:7999/api/sum?n1=20&n2=18
结果
{ "result": 38 }
https://www.cnblogs.com/cnxkey/articles/8777975.html(转自这里)

https://blog.csdn.net/u012234115/article/details/79596826(原作者)