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以及websocket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.c
├─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服务器

http_server.h

#pragma once#include <string>
#include <string.h>
#include <unordered_map>
#include <unordered_set>
#include <functional>
#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<bool (std::string, std::string, mg_connection *c, OnRspCallback)>;class HttpServer
{
public:HttpServer() {}~HttpServer() {}void Init(const std::string &port); // 初始化设置bool Start(); // 启动httpserverbool 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<std::string, ReqHandler> s_handler_map; // 回调函数映射表private:// 静态事件响应函数static void OnHttpWebsocketEvent(mg_connection *connection, int event_type, void *event_data);static void HandleHttpEvent(mg_connection *connection, http_message *http_req);static void SendHttpRsp(mg_connection *connection, std::string rsp);static int isWebsocket(const mg_connection *connection); // 判断是否是websoket类型连接static void HandleWebsocketMessage(mg_connection *connection, int event_type, websocket_message *ws_msg); static void SendWebsocketMsg(mg_connection *connection, std::string msg); // 发送消息到指定连接static void BroadcastWebsocketMsg(std::string msg); // 给所有连接广播消息static std::unordered_set<mg_connection *> s_websocket_session_set; // 缓存websocket连接std::string m_port;    // 端口mg_mgr m_mgr;          // 连接管理器
};

http_server.cpp

#include <utility>
#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();// 其他http设置// 开启 CORS，本项只针对主页加载有效// s_server_option.extra_headers = "Access-Control-Allow-Origin: *";
}bool HttpServer::Start()
{mg_mgr_init(&m_mgr, NULL);mg_connection *connection = mg_bind(&m_mgr, m_port.c_str(), HttpServer::OnHttpWebsocketEvent);if (connection == NULL)return false;// for both http and websocketmg_set_protocol_http_websocket(connection);printf("starting http server at port: %s\n", m_port.c_str());// loopwhile (true)mg_mgr_poll(&m_mgr, 500); // msreturn true;
}void HttpServer::OnHttpWebsocketEvent(mg_connection *connection, int event_type, void *event_data)
{// 区分http和websocketif (event_type == MG_EV_HTTP_REQUEST){http_message *http_req = (http_message *)event_data;HandleHttpEvent(connection, http_req);}else if (event_type == MG_EV_WEBSOCKET_HANDSHAKE_DONE ||event_type == MG_EV_WEBSOCKET_FRAME ||event_type == MG_EV_CLOSE){websocket_message *ws_message = (struct websocket_message *)event_data;HandleWebsocketMessage(connection, event_type, ws_message);}
}// ---- simple http ---- //
static bool route_check(http_message *http_msg, char *route_prefix)
{if (mg_vcmp(&http_msg->uri, route_prefix) == 0)return true;elsereturn 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::SendHttpRsp(mg_connection *connection, std::string rsp)
{// --- 未开启CORS// 必须先发送header, 暂时还不能用HTTP/2.0mg_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);// --- 开启CORS/*mg_printf(connection, "HTTP/1.1 200 OK\r\n""Content-Type: text/plain\n""Cache-Control: no-cache\n""Content-Length: %d\n""Access-Control-Allow-Origin: *\n\n""%s\n", rsp.length(), rsp.c_str()); */
}void HttpServer::HandleHttpEvent(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, &HttpServer::SendHttpRsp);}// 其他请求if (route_check(http_req, "/")) // index pagemg_serve_http(connection, http_req, s_server_option);else if (route_check(http_req, "/api/hello")) {// 直接回传SendHttpRsp(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);SendHttpRsp(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");}
}// ---- websocket ---- //
int HttpServer::isWebsocket(const mg_connection *connection)
{return connection->flags & MG_F_IS_WEBSOCKET;
}void HttpServer::HandleWebsocketMessage(mg_connection *connection, int event_type, websocket_message *ws_msg)
{if (event_type == MG_EV_WEBSOCKET_HANDSHAKE_DONE){printf("client websocket connected\n");// 获取连接客户端的IP和端口char addr[32];mg_sock_addr_to_str(&connection->sa, addr, sizeof(addr), MG_SOCK_STRINGIFY_IP | MG_SOCK_STRINGIFY_PORT);printf("client addr: %s\n", addr);// 添加 sessions_websocket_session_set.insert(connection);SendWebsocketMsg(connection, "client websocket connected");}else if (event_type == MG_EV_WEBSOCKET_FRAME){mg_str received_msg = {(char *)ws_msg->data, ws_msg->size};char buff[1024] = {0};strncpy(buff, received_msg.p, received_msg.len); // must use strncpy, specifiy memory pointer and length// do sth to process requestprintf("received msg: %s\n", buff);SendWebsocketMsg(connection, "send your msg back: " + std::string(buff));//BroadcastWebsocketMsg("broadcast msg: " + std::string(buff));}else if (event_type == MG_EV_CLOSE){if (isWebsocket(connection)){printf("client websocket closed\n");// 移除sessionif (s_websocket_session_set.find(connection) != s_websocket_session_set.end())s_websocket_session_set.erase(connection);}}
}void HttpServer::SendWebsocketMsg(mg_connection *connection, std::string msg)
{mg_send_websocket_frame(connection, WEBSOCKET_OP_TEXT, msg.c_str(), strlen(msg.c_str()));
}void HttpServer::BroadcastWebsocketMsg(std::string msg)
{for (mg_connection *connection : s_websocket_session_set)mg_send_websocket_frame(connection, WEBSOCKET_OP_TEXT, msg.c_str(), strlen(msg.c_str()));
}bool HttpServer::Close()
{mg_mgr_free(&m_mgr);return true;
}

main.cpp

#include <iostream>
#include <memory>
#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<std::string, ReqHandler> HttpServer::s_handler_map;
std::unordered_set<mg_connection *> HttpServer::s_websocket_session_set;bool handle_fun1(std::string url, std::string body, mg_connection *c, OnRspCallback rsp_callback)
{// do sthstd::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 sthstd::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<HttpServer>(new HttpServer);http_server->Init(port);// add handlerhttp_server->AddHandler("/api/fun1", handle_fun1);http_server->AddHandler("/api/fun2", handle_fun2);http_server->Start();return 0;
}

index.html

<!DOCTYPE html>
<html>
<head><title>RESTful API demo</title><script src="//code.jquery.com/jquery-1.11.0.min.js"></script>
<script type="text/javascript">// simple http$(document).ready(function(){$("button").click(function(){$.get("/api/hello",function(data, status){console.log("get rsp: ", data);$('#result1').html(data);});});});$(document).on('keyup', '#n1, #n2', function() {$.ajax({url: '/api/sum',method: 'POST',dataType: 'json',data: { n1: $('#n1').val(), n2: $('#n2').val() },success: function(json) {console.log("post rsp: ", json);$('#result2').html(json.result);}});});// websocketvar websocket = new WebSocket('ws://' + location.host + '/ws');websocket.onopen = function (ev) {console.log(ev.data);};websocket.onerror = function (ev) {console.log(ev.data);};websocket.onclose = function (ev) {console.log(ev.data);};websocket.onmessage = function (ev) {console.log(ev.data);document.getElementById("ws_text").innerHTML = ev.data;};window.onload = function () {document.getElementById('send_button').onclick = function (ev) {var msg = document.getElementById('send_input').value;websocket.send(msg);};};
</script>
</head>
<body><h1>c++ httpserver demo</h1><h2>simple http</h2><h3>GET</h3><div><button id="btn">get request</button></div><div><label>Result1:</label> <span id="result1">&nbsp;</span></div><h3>POST</h3><div><label>Number 1:</label> <input type="text" id="n1" /></div><div><label>Number 2:</label> <input type="text" id="n2" /></div><div><label>Result2:</label> <span id="result2">&nbsp;</span></div><h2>websocket</h2><div><span id="ws_text">&nbsp;</span><br /><input type="text" id="send_input" /><button id="send_button">Send</button></div></body>
</html>

服务器支持host静态页面资源
服务器支持前端页面的热加载
服务器支持http和websocket两种方式的接口
服务器可以添加头格式来开启跨域（CORS）加载支持
服务器支持websocket单一连接发消息和广播消息
服务器支持管理websocket的session
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
如果需要回传json格式，可以序列化成字符串，在前端解析

http客户端

http_client.h

#pragma once
#include <string>
#include <functional>
#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<void (std::string)>;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());// loopwhile (s_exit_flag == 0)mg_mgr_poll(&mgr, 500);mg_mgr_free(&mgr);
}

main.cpp

#include <iostream>
#include "http_client.h"void handle_func(std::string rsp)
{// do sth according to rspstd::cout << "http rsp1: " << rsp << std::endl;
}int main()
{// 拼完整url，带参数，暂时只写了GET请求std::string url1 = "http://127.0.0.1:7999/api/hello";HttpClient::SendReq(url1, handle_func);std::string url2 = "http://127.0.0.1:7999/api/fun2";HttpClient::SendReq(url2, [](std::string rsp) { std::cout << "http rsp2: " << rsp << std::endl; });system("pause");return 0;
}

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 }

websocket的测试可以用工具也可以用内嵌网页，查看连接状态以及双向发消息

网页截图

源码

csdn：demo

github: demo

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C++实现轻量级极简httpserver和httpclient（提供http和websocket接口）

http服务器

http客户端

测试

源码

C++实现轻量级极简httpserver和httpclient（提供http和websocket接口）相关推荐

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