前面我们写了基于bufferevent的server端，这里我们写1个基于bufferevent的client端。

test_libevent_client.cpp：

#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

static const int PORT = 5001;
static char g_szWriteMsg[256] = {0};
static char g_szReadMsg[256] = {0};
static int g_iCnt = 0;
static void conn_writecb(struct bufferevent *, void *);
static void conn_readcb(struct bufferevent *, void *);
static void conn_eventcb(struct bufferevent *, short, void *);

int
main(int argc, char **argv)
{
    struct event_base *base;

    base = event_base_new();
    if (!base) {
        fprintf(stderr, "Could not initialize libevent!\n");
        return 1;
    }

	struct sockaddr_in sin;
    memset(&sin, 0, sizeof(sin));
	
	//也可以用这种方式赋IP
	//evutil_inet_pton(AF_INET, "192.168.3.99", &sin.sin_addr.s_addr);
    sin.sin_addr.s_addr = inet_addr("192.168.3.99");
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);

	//调用客户端代码
	//-1内部创建socket
	//BEV_OPT_CLOSE_ON_FREE: bufferevent关闭时,socket也要同时关闭
    struct bufferevent* bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
    if (bev == NULL ) {
        fprintf(stderr, "socket init failed\n");
        return 1;
    }
	
	timeval t1 = {5, 0}; //5秒
	bufferevent_set_timeouts(bev, &t1, 0); //65秒读取超时 超时触发event_cb
    
	//设置回调函数
    bufferevent_setcb(bev, conn_readcb, conn_writecb, conn_eventcb, NULL);
	//有读、写权限
    bufferevent_enable(bev, EV_READ | EV_WRITE);
	
    //连接服务端
    int flag = bufferevent_socket_connect(bev, (struct sockaddr*)&sin, sizeof(sin));
    if (-1 == flag) {
        fprintf(stderr, "connect failed\n");
        return 1;
    }
    
	//进入事件主循环
    event_base_dispatch(base); //循环阻塞
    event_base_free(base);

    return 0;
}

static void
conn_writecb(struct bufferevent *bev, void *user_data) {
    printf("touch conn_writecb\n");

    if ( strlen(g_szWriteMsg) > 0 ) {
        bufferevent_write(bev, g_szWriteMsg, strlen(g_szWriteMsg));
		
        memset(g_szWriteMsg, 0x00, sizeof(g_szWriteMsg));
    }
}

static void
conn_readcb(struct bufferevent *bev, void *user_data) {
    printf("touch conn_readcb\n");
    memset(g_szReadMsg, 0x00, sizeof(g_szReadMsg));
    struct evbuffer *input = bufferevent_get_input(bev);
    size_t sz = evbuffer_get_length(input);
    if (sz > 0) {
        bufferevent_read(bev, g_szReadMsg, sz);
        printf("ser:>>%s\n", g_szReadMsg);
        memset(g_szWriteMsg, 0, sizeof(g_szWriteMsg));
        snprintf(g_szWriteMsg, sizeof(g_szWriteMsg)-1, "hi server,this count is %d", g_iCnt);
        g_iCnt++;
    }
}

static void
conn_eventcb(struct bufferevent *bev, short events, void *user_data) {
    if (events & BEV_EVENT_EOF) {
        printf("Connection closed.\n");
    } else if (events & BEV_EVENT_ERROR) {
        printf("Got an error on the connection: %s\n",
			strerror(errno));/*XXX win32*/
    } else if (events & BEV_EVENT_CONNECTED) {
        //连接成功时走这里，并且要客户端第一次触发读事件后连接才真正建立起来
        printf("connect success\n");
        const char* msg = "hi server,how are you?";
        bufferevent_write(bev, msg, strlen(msg));
		
        return;
    }
	
    bufferevent_free(bev);
}

执行结果如下：