libevent evhttp学习——http服务端

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);
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2. 绑定地址和端口

   int evhttp_bind_socket(struct evhttp *http, const char *address, ev_uint16_t port);
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3. 设置处理函数

   void evhttp_set_gencb(struct evhttp *http,    void (*cb)(struct evhttp_request *, void *), void *arg);
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4. 派发事件循环

   int event_base_dispatch(struct event_base *);
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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;}
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编译

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