bufferevent client

使用libevent实现TCP客户端读写回调

最新推荐文章于 2025-10-18 14:56:18 发布

原创最新推荐文章于 2025-10-18 14:56:18 发布 · 166 阅读

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#bufferevent #connect

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该代码示例展示了如何使用libevent库创建一个TCP客户端，实现了读取、写入和事件回调功能。客户端连接到指定IP和端口，并从文件读取数据发送到服务器，同时接收服务器的响应并在控制台打印。

#include <event2/event.h>
#include <event2/listener.h>
#include <string.h>
#include <iostream>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <event2/listener.h>
#include <event2/bufferevent.h>
using namespace std;
#define SPORT 5001

static void CLINET_READ_CB(bufferevent* ev, void* arg)
{
    cout<<"[R]"<<endl;
    char szBuff[1024];
    int read_len = 0;
    
    memset(szBuff, 0x00, sizeof(szBuff));
    read_len = bufferevent_read(ev, szBuff, sizeof(szBuff)-1);
    cout<<"read data:"<<szBuff<<endl;
    /*if (strstr(szBuff, "quit"))
    {
        cout<<"quit"<<endl;
        bufferevent_free(ev);
        return;
    }
    bufferevent_write(ev, "OK", 2);
    */
}

static void CLINET_WRITE_CB(bufferevent* ev, void* arg)
{
    cout<<"[W]"<<endl;
    FILE* fp = (FILE*)arg;
    int read_len = 0;
    char szBuff[1024];
    
    memset(szBuff, 0x00, sizeof(szBuff));
    read_len = fread(szBuff, 1, sizeof(szBuff)-1, fp);
    if (read_len <= 0)
    {
        fclose(fp);
        //读取完毕后不释放，防止缓存中数据没有发送完
        //bufferevent_free(ev);
        bufferevent_disable(ev, EV_WRITE);
        return;
    }
    cout<<szBuff<<endl;
    bufferevent_write(ev, szBuff, read_len);
    
}

//超时、出错、断开连接时事件回调函数被调起
static void CLINET_EVENT_CB(bufferevent* ev, short what, void* arg)
{
    cout<<"[E]"<<endl;

    //超时操作，则断开连接
    if (what&BEV_EVENT_TIMEOUT)
    {
        cout<<"timeout"<<endl;
        bufferevent_free(ev);
        return;
    }
    else if (what&BEV_EVENT_CONNECTED)
    {
        cout<<"connected"<<endl;
        //触发write事件
        bufferevent_trigger(ev, EV_WRITE, 0);
    }
    else if (what&BEV_EVENT_ERROR)
    {
        cout<<"error"<<endl;
        bufferevent_free(ev);
        return;
    }
    else if (what&BEV_EVENT_EOF)
    {
        cout<<"BEV_EVENT_EOF"<<endl;
        bufferevent_free(ev);
        return;
    }
    else 
    {
        cout<<"others"<<endl;
        bufferevent_free(ev);
        return;
    }
}


int main()
{
    int res = 0;
    FILE* fp = NULL;
    //创建libevent的上下文
    event_base * base = event_base_new();
    if (!base)
    {
        cerr << "event_base_new error!" << endl;
        return -1;
    }
    

    bufferevent* pbev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
    
    //设置并绑定ip地址和端口
    sockaddr_in sn;
    memset(&sn, 0, sizeof(sn));
    sn.sin_family = AF_INET;
    sn.sin_port = htons(SPORT);
    evutil_inet_pton(AF_INET, "127.0.0.1", &sn.sin_addr.s_addr);
    
    fp = fopen("Makefile", "rb");
    if (!fp)
    {
        cerr<<"fopen error"<<endl;
        return -1;
    }
    bufferevent_setcb(pbev, CLINET_READ_CB, CLINET_WRITE_CB, CLINET_EVENT_CB, (void*)fp);
    bufferevent_enable(pbev, EV_READ|EV_WRITE);
    res = bufferevent_socket_connect(pbev, (sockaddr*)&sn, sizeof(sn));
    if (res == 0)
    {
        cout<<"connect success"<<endl;
    }

    //事件分发处理
    event_base_dispatch(base);
    event_base_free(base);
    return 0;
}