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0. 前言

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本文中用到的Log.hpp在笔者的历史文章中都有涉及，这里就不再粘贴源码了，学习地址如下：https://blog.csdn.net/weixin_73870552/article/details/145434855?spm=1001.2014.3001.5501。

TCP相对于UDP更加复杂，这里只介绍TCP的封装，学习完后，大家可以自己尝试UDP的封装。

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1. Socket.hpp

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采用模版方法类的设计模式，基类方法由子类实现

#pragma once#include <iostream>
#include <string>
#include <cstring>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>#define Convert(addrptr) ((struct sockaddr*)addrptr)// 错误码
enum {SocketError = 1,BindError,ListenError
};const static int defaultsockfd = -1;
const int backlog = 5;      // 这个参数后面讲// 封装一个基类，Socket接口类
// 设计模式：模版方法类
class Socket
{
public:virtual ~Socket() {}virtual void CreateSocketOrDie() = 0;               // 创建套接字virtual void BindSocketOrDie(uint16_t port) = 0;    // 绑定virtual void ListenSocketOrDie(int backlog) = 0;    // 监听virtual Socket* AcceptConnection(std::string *peerip, uint16_t *peerport) = 0; virtual bool ConnectServer(std::string &serverip, uint16_t serverport) = 0;virtual int GetSockFd() = 0;virtual void SetSockFd(int sockfd) = 0;virtual void CloseSocket() = 0;virtual bool Recv(std::string *buffer, int size) = 0;virtual void Send(std::string &send_str) = 0;
public:void BuildListenSocketMethod(uint16_t port, int backlog){CreateSocketOrDie();BindSocketOrDie(port);ListenSocketOrDie(backlog);}bool BuildConnectSocketMethod(std::string &serverip, uint16_t serverport){CreateSocketOrDie();return ConnectServer(serverip, serverport);}void BuildNormalSocketMethod(int sockfd){SetSockFd(sockfd);}
};// TCP
class TcpSocket : public Socket
{
public:TcpSocket(int sockfd = defaultsockfd): _sockfd(sockfd){}~TcpSocket(){}void CreateSocketOrDie() override{_sockfd = ::socket(AF_INET, SOCK_STREAM, 0);if(_sockfd < 0) exit(SocketError);}void BindSocketOrDie(uint16_t port) override{struct sockaddr_in local;memset(&local, 0, sizeof(local));local.sin_family = AF_INET;local.sin_addr.s_addr = INADDR_ANY;local.sin_port = htons(port);int n = ::bind(_sockfd, Convert(&local), sizeof(local));if(n < 0) exit(BindError);}void ListenSocketOrDie(int backlog) override{int n = ::listen(_sockfd, backlog);if(n < 0) exit(ListenError);}Socket* AcceptConnection(std::string *peerip, uint16_t *peerport) override{struct sockaddr_in peer;socklen_t len = sizeof(peer);int newsockfd = ::accept(_sockfd, Convert(&peer), &len);if(newsockfd < 0) return nullptr;*peerip = inet_ntoa(peer.sin_addr);*peerport = ntohs(peer.sin_port);Socket *s = new TcpSocket(newsockfd);return s;}bool ConnectServer(std::string &serverip, uint16_t serverport) override{struct sockaddr_in server;memset(&server, 0, sizeof(server));server.sin_family = AF_INET;server.sin_addr.s_addr = inet_addr(serverip.c_str());server.sin_port = htons(serverport);int n = ::connect(_sockfd, Convert(&server), sizeof(server));if(n == 0) return true;else return false;}int GetSockFd() override{return _sockfd;}void SetSockFd(int sockfd) override{_sockfd = sockfd;}void CloseSocket() override{if(_sockfd > defaultsockfd) ::close(_sockfd);}bool Recv(std::string *buffer, int size) override{char inbuffer[size];ssize_t n = recv(_sockfd, inbuffer, size-1, 0);if(n > 0){inbuffer[n] = 0;*buffer += inbuffer; return true;}else if(n == 0) return false;else return false;}void Send(std::string &send_str) override{// 这一块涉及到多路转接，我们之后统一说send(_sockfd, send_str.c_str(), send_str.size(), 0);}private:int _sockfd;
};

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2. 简单的使用介绍

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1. 服务端

#include <iostream>
#include <string>
#include <memory>
#include <unistd.h>
#include "Log.hpp"
#include "Socket.hpp"// ./server localport
int main(int argc, char *argv[])
{if(argc != 2){std::cout << "Usage: " << argv[0] << "port" << std::endl;return 0;}uint16_t localport = std::stoi(argv[1]);std::unique_ptr<TcpSocket> tsvr(new TcpSocket());tsvr->BuildListenSocketMethod(localport, backlog);while(true){std::string peerip;uint16_t peerport;lg.LogMessage(Debug, "ready to accept, listensocketfd: %d\n", tsvr->GetSockFd());Socket *newsock = tsvr->AcceptConnection(&peerip, &peerport);if(newsock == nullptr) continue;lg.LogMessage(Info, "get a new link... sockfd: %d, client info: %s:%d\n", newsock->GetSockFd(), peerip.c_str(), peerport);while(true){std::string buffer;newsock->Recv(&buffer, 1024);std::cout << "get a message: " << buffer.c_str() << std::endl;sleep(1);}// 注意资源的释放newsock->CloseSocket();delete newsock;}tsvr->CloseSocket();return 0;
}

2. 客户端

#include <iostream>
#include <unistd.h>
#include <memory>
#include "Socket.hpp"// ./client serverip serverport
int main(int argc, char* argv[])
{if(argc != 3){std::cout << "Usage: " << argv[0] << " serverip serverport" << std::endl;return 0;}std::string serverip = argv[1];uint16_t serverport = std::stoi(argv[2]);std::unique_ptr<TcpSocket> tsvr(new TcpSocket());if(!tsvr->BuildConnectSocketMethod(serverip, serverport)){std::cerr << "connect " << serverip << ":" << serverport << " failed" << std::endl;return 0;}std::cout << "connect " << serverip << ":" << serverport << " success" << std::endl;std::string message = "a";char n = 'b';while(true){tsvr->Send(message);message.push_back(n++);sleep(1);}tsvr->CloseSocket();return 0;
}

3. 通信测试

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