本文共 4432 字，大约阅读时间需要 14 分钟。
http://blog.csdn.net/y396397735/article/details/50680359
本例实现如下功能：
支持多客户端与一个服务端进行通信，客户端给服务端发送字符串数据，服务端将字符串中小写转为大写后发送回客户端，客户端打印输出经转换后的字符串。
例如：发送
abcde，打印输出
ABCDE 服务端源码如下：
/*server.c*/#include #include #include #include #include #include #include #define BUFSIZE 666#define SERV_PORT 8000#define OPEN_MAX 1024int main(){ int i, j, maxi, listenfd, connfd, sockfd; int nready, efd, res; ssize_t n; char buf[BUFSIZE], str[INET_ADDRSTRLEN]; socklen_t clilen; int client[OPEN_MAX]; struct sockaddr_in cliaddr, servaddr; struct epoll_event tep, ep[OPEN_MAX];//监听事件 /*分配一个网络通信套接字，监听文件描述符listenfd*/ listenfd = socket(AF_INET, SOCK_STREAM, 0); /*初始化 IP类型 端口*/ bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(SERV_PORT); /*将listenfd绑定服务端地址*/ bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)); /*监听请求*/ listen(listenfd, 20); /*将客户端标识初始化为-1*/ for(i = 0; i < OPEN_MAX; i++){ client[i] = -1; } maxi = -1; /*告诉内核要监听的文件描述符个数 OPEN_MAX = 1024*/ efd = epoll_create(OPEN_MAX); if(efd == -1){ perror("epoll_create"); } tep.events = EPOLLIN;/*监听文件描述符的可读事件*/ tep.data.fd = listenfd;/*设置为监听的文件描述符*/ /*控制epoll监控的文件描述符上的事件*/ res = epoll_ctl(efd, EPOLL_CTL_ADD/*注册新的fd到efd*/, listenfd, &tep); if(res == -1) perror("epoll_ctl"); for(;;){ /*等待所监控文件描述符上有事件的产生，阻塞监听*/ nready = epoll_wait(efd, ep, OPEN_MAX, -1); if(nready == -1) perror("epoll_wait"); for(i = 0; i < nready; i++){ if(!(ep[i].events & EPOLLIN))/*若不是EPOLLIN事件，不做往下的处理*/ continue; if(ep[i].data.fd == listenfd){ /*若是EPOLLIN，执行连接，接受请求*/ clilen = sizeof(cliaddr); /*接受请求，分配新文件描述符connfd进行通信*/ connfd = accept(listenfd, (struct sockaddr*)&cliaddr, &clilen); printf("received from %s at PORT %d\n", (char*)inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port)); /*若将此新客户端添加至客户端集中*/ for(j = 0; j < OPEN_MAX; j++) if(client[j] < 0){ client[j] = connfd; break; } if(j == OPEN_MAX) perror("客户端超过限制"); if(j > maxi) maxi = j;//保证maxi为最大文件描述符 tep.events = EPOLLIN; tep.data.fd = connfd; res = epoll_ctl(efd, EPOLL_CTL_ADD/*注册新的connfd到efd*/, connfd, &tep); if(res == -1) perror("epoll_ctl"); }else{ /*处理efd中监听的客户端请求*/ sockfd = ep[i].data.fd; n = read(sockfd, buf, BUFSIZE); if(n == 0){ /*读取若为空*/ for(j = 0; j <= maxi; j++){ if(client[j] == sockfd){ client[j] = -1; break; } } /*清除对sockfd文件描述符事件的监听*/ res = epoll_ctl(efd, EPOLL_CTL_DEL, sockfd, NULL); if(res == -1) perror("epoll_ctl"); close(sockfd); printf("client[%d] closed connection\n", j); }else{ /*非空则处理客户端信息*/ for(j = 0; j
客户端源码如下：
/*client.c*/#include #include #include #include #include #include #include #include #define BUFSIZE 666#define SERV_PORT 8000#define OPEN_MAX 1024int main(int argc, char *argv[]){ struct sockaddr_in servaddr; char buf[BUFSIZE]; int sockfd, n; sockfd = socket(AF_INET, SOCK_STREAM, 0); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr); servaddr.sin_port = htons(SERV_PORT); /*连接服务端*/ connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)); while(fgets(buf, BUFSIZE, stdin) != NULL){ /*通过sockfd给服务端发送数据*/ write(sockfd, buf, strlen(buf)); n = read(sockfd, buf, BUFSIZE); if(n == 0) printf("the other side has been closed.\n"); else/*打印输出服务端传过来的数据*/ write(STDOUT_FILENO, buf, n); } close(sockfd); return 0;} 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
编译及执行
在终端1先执行：
yu@ubuntu:~/Linux/217/epoll$ lsclient.c server.cyu@ubuntu:~/Linux/217/epoll$ gcc -o client client.cyu@ubuntu:~/Linux/217/epoll$ gcc -o server server.cyu@ubuntu:~/Linux/217/epoll$ ./server 1 2 3 4 5
另开一终端2：
yu@ubuntu:~/Linux/217/epoll$ ./clienthey how are youHEY HOW ARE YOUbyeBYE 1 2 3 4 5 6
再另开一终端3：
yu@ubuntu:~/Linux/217/epoll$ ./clienti am here 007I AM HERE 007heheHEHE 1 2 3 4 5 6
最后开一终端4：
yu@ubuntu:~/Linux/217/epoll$ ./clienti am 008I AM 008zai jianZAI JIAN 1 2 3 4 5 6
关闭3个客户端(CTR+C)后服务端窗口：
yu@ubuntu:~/Linux/217/epoll$ ./serverreceived from 127.0.0.1 at PORT 58385received from 127.0.0.1 at PORT 58386received from 127.0.0.1 at PORT 58387client[2] closed connectionclient[1] closed connectionclient[0] closed connection 1 2 3 4 5 6 7
