C++多线程实现TCP服务器端同时和多个客户端通信

通讯建立后首先由服务器端发送消息，客户端接收消息；接着客户端发送消息，服务器端接收消息，实现交互发送消息。

服务器同时可以和多个客户端建立连接，进行交互；

在某次交互中，服务器端或某客户端有一方发送"end"即终止服务器与其的通信；服务器还可以继续接收其他客户端的请求，与其他客户端通信。

服务器端

#include <WinSock2.h>
#include <WS2tcpip.h>
#include <iostream>
using namespace std;
#pragma comment(lib, "ws2_32.lib")
#define PORT 65432
DWORD WINAPI ThreadFun(LPVOID lpThreadParameter);
int main() 
{
	//初始化winsock2.DLL
	WSADATA wsaData;
	WORD wVersionRequested = MAKEWORD(2, 2);
	if (WSAStartup(wVersionRequested, &wsaData) != 0)
	{
		cout << "加载winsock.dll失败！" << endl;
		return 0;
	}
	//创建套接字
	SOCKET  sock_server;
	if ((sock_server = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
	{
		cout << "创建套接字失败！错误代码：" << WSAGetLastError() << endl;
		WSACleanup();
		return 0;
	}
	//绑定端口和Ip
	sockaddr_in addr;
	addr.sin_family = AF_INET;
	addr.sin_port = htons(PORT);
	inet_pton(AF_INET, "127.0.0.1", &addr.sin_addr);//绑定本机的环回地址
	if (SOCKET_ERROR == bind(sock_server, (SOCKADDR*)&addr, sizeof(sockaddr_in)))
	{
		cout << "地址绑定失败！错误代码：" << WSAGetLastError() << endl;
		closesocket(sock_server);
		WSACleanup();
		return 0;
	}
	//将套接字设为监听状态
	listen(sock_server, 0);
	
	//主线程循环接收客户端的连接
	while (1) 
	{
		sockaddr_in addrClient;
		int len = sizeof(sockaddr_in);
		//接收成功返回与client通讯的socket
		SOCKET con = accept(sock_server, (SOCKADDR*)&addrClient, &len);
		if (con != INVALID_SOCKET) 
		{
			//创建线程 并且传入与client通讯的套接字
			HANDLE hThread = CreateThread(NULL, 0, ThreadFun, (LPVOID)con, 0, NULL);
			CloseHandle(hThread); //关闭对线程的引用
		}
	}
	closesocket(sock_server);
	WSACleanup();
	return 0;
}
//线程通讯部分
DWORD WINAPI ThreadFun(LPVOID lpThreadParameter) 
{
	//与客户端通讯 先发送再接收数据
	SOCKET sock = (SOCKET)lpThreadParameter;
	cout << "成功和" << sock << "建立连接！" << endl;
	while (1)
	{
		char msgbuffer[1000];//字符缓冲区
		printf("服务器向%d发送数据：\n", sock);
		cin.getline(msgbuffer, sizeof(msgbuffer));
		int size = send(sock, msgbuffer, sizeof(msgbuffer), 0);//给客户端发送一段信息
		if (strcmp(msgbuffer, "end\0") == 0)
		{
			cout << "关闭和" << sock << "的连接！" << endl;
			return 0;
		}
		if (size == SOCKET_ERROR || size == 0)
		{
			cout << "发送信息失败！错误代码：" << WSAGetLastError() << endl;
			return 0;
		}
		else cout << "信息发送成功！" << endl;
		
		//接收客户端数据
		msgbuffer[999] = { 0 };
		int ret = recv(sock, msgbuffer, sizeof(msgbuffer), 0);
		if(ret == SOCKET_ERROR || ret == 0)
		{
			cout << sock << "断开了连接！" << endl;
			break;
		}
		else cout << sock << "  说: " << msgbuffer << endl;
	}
	return 0;
}

客户端

#include <winsock2.h>
#include <WS2tcpip.h>
#include <iostream>
using  namespace std;
#pragma comment(lib, "ws2_32.lib")
#define PORT 65432
int  main() 
{
	//初始化winsock2.DLL
	WSADATA wsaData;
	WORD wVersionRequested = MAKEWORD(2, 2);
	if (WSAStartup(wVersionRequested, &wsaData) != 0)
	{
		cout << "加载winsock.dll失败！" << endl;
		return 0;
	}
	//创建套接字
	SOCKET  sock_client; 
	if ((sock_client = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
	{
		cout << "创建套接字失败！错误代码：" << WSAGetLastError() << endl;
		WSACleanup();
		return 0;
	}
	//连接服务器
	sockaddr_in   addr;
	addr.sin_family = AF_INET;
	addr.sin_port = htons(PORT);
	inet_pton(AF_INET, "127.0.0.1", &addr.sin_addr);//绑定本机的环回地址
	int len = sizeof(sockaddr_in);
	if (connect(sock_client, (SOCKADDR*)&addr, len) == SOCKET_ERROR) {
		cout << "连接失败！错误代码：" << WSAGetLastError() << endl;
		return 0;
	}
	//实现交互部分，客户端先接收后发送数据
	while (1)
	{
		//接收服务端的消息
		char msgbuffer[1000] = { 0 };
		int size = recv(sock_client, msgbuffer, sizeof(msgbuffer), 0);
		if (strcmp(msgbuffer, "end\0") == 0)
		{
			cout << "服务器端已经关闭连接！" << endl;
			break;
		}
		if (size < 0)
		{
			cout << "接收信息失败！错误代码：" << WSAGetLastError() << endl;
			break;
		}
		else if (size == 0)
		{
			cout << "对方已经关闭连接" << endl;
			break;
		}
		else cout << "The message from Server:" << msgbuffer << endl;

		//从键盘输入一行文字发送给服务器
		msgbuffer[999] =  0 ;
		cout << "从键盘输入发给服务器的信息：" << endl;
		cin.getline(msgbuffer, sizeof(msgbuffer));
		if (strcmp(msgbuffer, "end\0") == 0)
		{
			cout << "关闭连接！" << endl;
			break;
		}
		int ret = send(sock_client, msgbuffer, sizeof(msgbuffer), 0);
		if (ret == SOCKET_ERROR || ret == 0)
		{
			cout << "发送信息失败！错误代码：" << WSAGetLastError() << endl;
			break;
		}
		else cout << "信息发送成功！" << endl;
	}
	closesocket(sock_client);
	WSACleanup();
	return 0;
}

我们用建立连接时服务器端接收的客户端套接字来唯一标识该客户端。
服务器端可以随时接收客户端的连接并与其进行交互。

运行实例

实例展示了服务器端和两个客户端通信的运行过程，包括正常交互、交互过程中另一服务器请求建立连接、服务器主动断开连接和客户端主动断开连接等过程。