简单实现能够断线重连的TCP客户端

代码 

主要是借助了状态机来实现断线重连

client.hpp

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>using namespace std;#define RETRY_INTERVAL 1
#define MAX_RETRIES 5void Usage(const std::string& process)
{cout << "Usage: " << process << "argv[1]: server_ip and argv[2]: server_port" << endl; 
}enum ERR // 这里的出错状态码不用强枚举类型，因为exit()中必须传入整形，强枚举类型会编译报错
{SOCKFDERR = 1,BINDERR
};enum class Status // 强枚举类型
{NEW,            // 新建立的链接，还未初始化完的状态CONNECTIGN,     // 正在连接CONNECTED,      // 连接成功状态，或者重连成功状态DISCONNECTED,   // 重连失败CLOSED          // 连接关闭状态
};class Connection
{private:int _sockfd;uint16_t _serverport;   // 服务端的端口号string _serverip;       // 服务端的ipint  _retry_interval;   // 每次重连的时间间隔,单位是秒int _max_retries;       // 最大尝试重连次数Status _statu;          // 当前连接的状态public:Connection(uint16_t port,const string& ip) :_sockfd(-1),_serverport(port),_serverip(ip),_retry_interval(RETRY_INTERVAL),_max_retries(MAX_RETRIES),_statu(Status::NEW) {}void Connect(){// 1.创建socket_sockfd = socket(AF_INET,SOCK_STREAM,0);if(_sockfd < 0){cerr << "Create Sockfd Failed!" << endl;exit(SOCKFDERR);}// 2.connet,客户端是不需要bind的，因为在connet的时候，系统会给客户端随机分配端口号struct sockaddr_in server;memset(&server,0,sizeof(server));server.sin_family = AF_INET;server.sin_port = htons(_serverport);// p:process(进程), n(网络)-- 不太准确，但是好记忆inet_pton(AF_INET,_serverip.c_str(),&server.sin_addr);int n = connect(_sockfd,(struct sockaddr*)&server,sizeof(server)); // 自动绑定端口if(n < 0){Disconnect(); // 先重置连接的状态，关闭原来的套接字_statu = Status::DISCONNECTED; // 准备进行重连return;}// 连接成功了_statu = Status::CONNECTED;}int Sockfd() {return _sockfd; }// 重新连接void ReConnect(){// 其实就是不断调用Connect()int count = _max_retries;while(count > 0){cout << "正在重新连接，剩余重连次数： " << count << " 次..." << endl;Connect(); // 重新连接count--;if(_statu == Status::CONNECTED) return; // 重连成功直接返回sleep(_retry_interval);}// 重连失败_statu = Status::CLOSED;}// 关闭连接void Disconnect(){if(_sockfd != -1){close(_sockfd);_sockfd = -1;_statu = Status::CLOSED;}}Status GetStatu() { return _statu; }void Process(){// 简单的IOwhile(true){string inbuffer;cout << "Please Enter# ";getline(cin,inbuffer);if(inbuffer.size() == 0) continue;ssize_t n = send(_sockfd,inbuffer.c_str(),sizeof(inbuffer),0);if(n < 0){cout << "Send n : " << n << "errno: " << errno << " errno string: " << strerror(errno) << endl;_statu = Status::CLOSED;break; }else  {char buffer[1024];int m = recv(_sockfd,buffer,1023,0);if(m < 0){cout << "Recv m : " << "errno: " << errno << " errno string: " << strerror(errno) << endl;_statu = Status::CLOSED;break;}else if(m == 0){_statu = Status::DISCONNECTED;break;}else  {buffer[m] = 0;cout << "Server said: " << endl;cout << buffer << endl;}}}}~Connection() { Disconnect(); }
};class TcpClient
{private:Connection _conn; public:TcpClient(uint16_t port,const string& ip) : _conn(port,ip) {}void Execute(){while(true){switch(_conn.GetStatu()){case Status::NEW: _conn.Connect();break;case Status::CONNECTED:_conn.Process();break;case Status::DISCONNECTED:_conn.ReConnect();break;case Status::CLOSED:cout << "重连失败，关闭连接..." << endl;_conn.Disconnect();return;default:break;}}}~TcpClient() {}
};

main.cc

#include "client.hpp"int main(int argc,char* argv[])
{if(argc != 3){Usage(argv[0]);return 1;}string serverip = argv[1];uint16_t serverport = stoi(argv[2]);TcpClient client(serverport,serverip);client.Execute();return 0;
}

makefile

TcpClient:main.ccg++ -std=c++11 $^ -o $@.PHONY::clean
clean:rm -f TcpClient;