libevent evhttp学习——http服务端

时间：2022-03-13 03:30:34

http服务端相对客户端要简单很多，我们仍旧使用libevent-2.1.5版本，服务端接口和2.0版本没有区别

基本流程

http服务端使用到的借口函数及流程如下

  1. 创建event_base和evhttp

    struct event_base *event_base_new(void);
    struct evhttp *evhttp_new(struct event_base *base);

  2. 绑定地址和端口

    int evhttp_bind_socket(struct evhttp *http, const char *address, ev_uint16_t port);

  3. 设置处理函数

    void evhttp_set_gencb(struct evhttp *http,
    void (*cb)(struct evhttp_request *, void *), void *arg);

  4. 派发事件循环

    int event_base_dispatch(struct event_base *);

完整代码

服务器接收到请求后打印URL，并返回一段文本信息

#include "event2/http.h"
#include "event2/event.h"
#include "event2/buffer.h"

#include <stdlib.h>
#include <stdio.h>

void HttpGenericCallback(struct evhttp_request* request, void* arg)
{
const struct evhttp_uri* evhttp_uri = evhttp_request_get_evhttp_uri(request);
char url[8192];
    evhttp_uri_join(const_cast<struct evhttp_uri*>(evhttp_uri), url, 8192);

printf("accept request url:%s\n", url);

struct evbuffer* evbuf = evbuffer_new();
if (!evbuf)
    {
printf("create evbuffer failed!\n");
return ;
    }

    evbuffer_add_printf(evbuf, "Server response. Your request url is %s", url);
    evhttp_send_reply(request, HTTP_OK, "OK", evbuf);
    evbuffer_free(evbuf);
}

int main(int argc, char** argv)
{
if (argc != 2)
    {
printf("usage:%s port\n", argv[0]);
return 1;
    }

int port = atoi(argv[1]);
if (port == 0)
    {
printf("port error:%s\n", argv[1]);
return 1;
    }

struct event_base* base = event_base_new();
if (!base)
    {
printf("create event_base failed!\n");
return 1;
    }

struct evhttp* http = evhttp_new(base);
if (!http)
    {
printf("create evhttp failed!\n");
return 1;
    }

if (evhttp_bind_socket(http, "0.0.0.0", port) != 0)
    {
printf("bind socket failed! port:%d\n", port);
return 1;
    }

    evhttp_set_gencb(http, HttpGenericCallback, NULL);

    event_base_dispatch(base);
return 0;
}

编译

g++ http-server.cpp -I/opt/third_party/libevent/include -L/opt/third_party/libevent/lib -levent -o http-server
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