多人聊天室（epoll - Linux网络编程）

文章目录

- 零、效果展示
- 一、服务器代码
- 二、客户端代码
- 三、知识点
- - 1.bind()
- 四、改进方向
- 五、跟练视频

零、效果展示

一个服务器作为中转站，多个客户端之间可以相互通信。至少需要启动两个客户端。

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三个客户端互相通信
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一、服务器代码

chatServer.cpp

#include <cstdio>
#include <iostream>
#include <string>
#include <sys/epoll.h>  //epoll的头文件
#include <sys/socket.h> //socket的头文件
#include <unistd.h>     //close()的头文件
#include <netinet/in.h> //包含结构体 sockaddr_in
#include <map>          //保存客户端信息
#include <arpa/inet.h>  //提供inet_ntoa函数
using namespace std;const int MAX_CONNECT = 5; //全局静态变量,允许的最大连接数struct Client{int sockfd; //socket file descriptor 套接字文件描述符 string username;
};int main(){//创建一个epoll实例int epld = epoll_create(1);if(epld < 0){perror("epoll create error");return -1;}//创建监听的socketint sockfd = socket(AF_INET, SOCK_STREAM, 0);if(sockfd < 0){ //若socket创建失败,则返回-1perror("socket error");return -1;}//绑定本地ip和端口struct sockaddr_in addr;  //结构体声明,头文件是<netinet/in.h>addr.sin_family = AF_INET;addr.sin_addr.s_addr = htonl(INADDR_ANY);addr.sin_port  = htons(9999);int ret = bind(sockfd,(struct sockaddr*)&addr,sizeof(addr));if(ret < 0){printf("bind error\n");cout << "该端口号已被占用,请检查服务器是否已经启动。" << endl;return -1;}cout << "服务器中转站已启动,请加入客户端。" << endl;//监听客户端ret = listen(sockfd,1024);if(ret < 0){printf("listen error\n");return -1;}//将监听的socket加入epollstruct epoll_event ev;ev.events = EPOLLIN;ev.data.fd = sockfd;ret = epoll_ctl(epld,EPOLL_CTL_ADD,sockfd,&ev); //防御性编程，方便出bug时快速定位问题if(ret < 0){printf("epoll_ctl error\n");return -1;}//保存客户端信息map<int,Client> clients;int clientCount = 0; //添加一个客户端计数器//循环监听while(true){struct epoll_event evs[MAX_CONNECT];int n = epoll_wait(epld,evs,MAX_CONNECT,-1);if(n < 0){printf("epoll_wait error\n");break;}for(int i = 0; i < n; i ++){int fd = evs[i].data.fd;//如果是监听的fd收到消息,则表示有客户端进行连接了if(fd == sockfd){struct sockaddr_in client_addr;socklen_t client_addr_len = sizeof(client_addr);int client_sockfd = accept(sockfd, (struct sockaddr*) & client_addr, &client_addr_len);if(client_sockfd < 0){printf("accept error,连接出错\n");continue;}//将客户端的socket加入epollstruct epoll_event ev_client;ev_client.events = EPOLLIN; //检测客户端有没有消息过来ev_client.data.fd = client_sockfd;ret = epoll_ctl(epld, EPOLL_CTL_ADD,client_sockfd,&ev_client);if(ret < 0){printf("epoll_ctl error\n");break;} //iner_ntoa() 将客户端的IP地址从网络字节顺序转换为点分十进制字符串clientCount++; //有新的客户端加入时,增加计数器printf("客户端%d已连接: IP地址为 %s\n", clientCount, inet_ntoa(client_addr.sin_addr));//保存该客户端信息Client client;client.sockfd = client_sockfd;client.username = "";clients[client_sockfd] = client;}else{char buffer[1024];int n = read(fd, buffer, 1024);if(n < 0){break; //处理错误}else if(n == 0){//客户端断开连接close(fd);epoll_ctl(epld,EPOLL_CTL_DEL, fd ,0);clients.erase(fd);}else{ // n > 0string msg(buffer,n);//如果该客户端username为空,说明该消息是这个客户端的用户名if(clients[fd].username == ""){clients[fd].username = msg;}else{string name = clients[fd].username;//把消息发给其他所有客户端for(auto &c:clients){if(c.first != fd){string full_message = '[' + name + ']' + ':' + msg;write(c.first, full_message.c_str(), full_message.length());//write(c.first,('[' + name + ']' + ":" + msg).c_str(),msg.size() + name.size() + 4);}}}}}}}//关闭epoll实例close(epld);close(sockfd);return 0;
}

二、客户端代码

client.cpp

注意g++编译时要加 -pthread

#include <cstdio>
#include <iostream> 
#include <cstring>       //memset()的头文件
#include <sys/socket.h>  //socket(),connect()等函数的头文件
#include <netinet/in.h>  //sockaddr_in的头文件
#include <arpa/inet.h>   //inet_pton()函数的头文件
#include <unistd.h>      //close()函数的头文件
#include <pthread.h>     //pthread创建线程和管理线程的头文件
using namespace std;#define BUF_SIZE 1024
char szMsg[BUF_SIZE];//发送消息
void* SendMsg(void *arg){int sock = *((int*)arg);while(1){//scanf("%s",szMsg);fgets(szMsg,BUF_SIZE,stdin); //使用fgets代替scanfif(szMsg[strlen(szMsg) - 1] == '\n'){szMsg[strlen(szMsg)- 1] = '\0'; //去除换行符}if(!strcmp(szMsg,"QUIT\n") || !strcmp(szMsg,"quit\n")){close(sock);exit(0);}send(sock, szMsg, strlen(szMsg), 0);}return nullptr;
}//接收消息
void* RecvMsg(void * arg){int sock = *((int*)arg);char msg[BUF_SIZE];while(1){int len = recv(sock, msg, sizeof(msg)-1, 0);if(len == -1){cout << "系统挂了" << endl;return (void*)-1;}msg[len] = '\0';printf("%s\n",msg);}return nullptr;
}int main()
{//创建socketint hSock;hSock = socket(AF_INET, SOCK_STREAM, 0);if(hSock < 0){perror("socket creation failed");return -1;}//绑定端口sockaddr_in servAdr;memset(&servAdr, 0, sizeof(servAdr));servAdr.sin_family = AF_INET;servAdr.sin_port = htons(9999);if(inet_pton(AF_INET, "172.16.51.88", &servAdr.sin_addr) <= 0){perror("Invalid address");return -1;}//连接到服务器if(connect(hSock, (struct sockaddr*)&servAdr, sizeof(servAdr)) < 0){perror("连接服务器失败");cout << "请检查是否已启动服务器。" << endl;return -1;}else{printf("已连接到服务器，IP地址：%s，端口：%d\n", inet_ntoa(servAdr.sin_addr), ntohs(servAdr.sin_port));printf("欢迎来到私人聊天室,请输入你的聊天用户名:");}//创建线程pthread_t sendThread,recvThread;if(pthread_create(&sendThread, NULL, SendMsg, (void*)&hSock)){perror("创建发送消息线程失败");return -1;}if(pthread_create(&recvThread, NULL, RecvMsg, (void*)&hSock)){perror("创建接收消息线程失败");return -1;}//等待线程结束pthread_join(sendThread, NULL);pthread_join(recvThread, NULL);//关闭socketclose(hSock);return 0;
}