Windows下网络编程及多线程模型

Socket编程

要想客户端和服务器能在网络中通信，那必须得使用 Socket 编程。

服务端首先调用 socket() 函数，创建网络协议为 IPv4，以及传输协议为 TCP 的 Socket ，接着调用 bind() 函数，给这个 Socket 绑定一个 IP 地址和端口。然后，服务端可以调用 listen() 函数进行监听，进入了监听状态后，通过调用 accept() 函数，来从内核获取客户端的连接，如果没有客户端连接，则会阻塞等待客户端连接的到来。

客户端在创建好 Socket 后，调用 connect() 函数发起连接，该函数的参数要指明服务端的 IP 地址和端口号，接着就是开始三次握手。

在 TCP 连接的过程中，服务器的内核实际上为每个 Socket 维护了两个队列：

半连接队列
全连接队列

当 TCP 全连接队列不为空后，服务端的 accept() 函数，就会从内核中的 TCP 全连接队列里拿出一个已经完成连接的 Socket 返回应用程序，后续数据传输都用这个 Socket。因此，进行三次握手的Socket和传输数据的Socket是不一样的。

连接建立后，客户端和服务端就开始相互传输数据了，双方都可以通过 read() 和 write() 函数来读写数据。

下面看一下同步阻塞的方式实现的Socket通信。将两份cpp文件放在不同工程中，分别生成。

server.cpp

#include <stdio.h>
#include <windows.h>#pragma comment(lib, "ws2_32.lib")int main()
{//1. 请求协议版本WSADATA wsaData;WSAStartup(MAKEWORD(2, 2), &wsaData);if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) {printf("request failed!\n");return -1;}printf("request protocol success!\n");//2. 创建SocketSOCKET serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (serverSocket == SOCKET_ERROR) {printf("create failed!\n");WSACleanup();return -2;}printf("create socket success!\n");//3.创建协议族SOCKADDR_IN addr = { 0 };addr.sin_family = AF_INET; //协议版本addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.127");addr.sin_port = htons(10086);//0-65535 10000左右//4.绑定int r = bind(serverSocket, (sockaddr*)&addr, sizeof addr);if (-1 == r) {printf("bind failed!\n");closesocket(serverSocket);WSACleanup();return -2;}printf("bind success!\n");//5.监听r = listen(serverSocket, 10);if (-1 == r) {printf("listen failed!\n");closesocket(serverSocket);WSACleanup();return -2;}printf("listen success!\n");//6.等待客户端连接    阻塞   SOCKADDR_IN cAddr = { 0 };int len = sizeof(cAddr);SOCKET clientSocket = accept(serverSocket, (sockaddr*)&cAddr, &len);if (SOCKET_ERROR == clientSocket) {printf("serverd failed!\n");closesocket(clientSocket);WSACleanup();return -2;}printf("one client(%s) has connected server!\n", inet_ntoa(cAddr.sin_addr));//7.通信char buff[1024];while (1) {r = recv(clientSocket, buff, 1023, NULL);if (r > 0) {buff[r] = 0; // 添加'\0'printf(">>%s\n", buff);}}return 0;
}

client.cpp

#include <stdio.h>
#include <windows.h>#pragma comment(lib, "ws2_32.lib")int main()
{//1. 请求协议版本WSADATA wsaData;WSAStartup(MAKEWORD(2, 2), &wsaData);if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) {printf("request failed!\n");return -1;}printf("request protocol success!\n");//2. 创建SocketSOCKET clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (clientSocket == SOCKET_ERROR) {printf("create failed!\n");WSACleanup();return -2;}printf("create socket success!\n");//3.获取服务器协议族SOCKADDR_IN addr = { 0 };addr.sin_family = AF_INET; //协议版本addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.127");addr.sin_port = htons(10086);//0-65535 10000左右//4.连接服务器int r = connect(clientSocket, (sockaddr*)&addr, sizeof addr);if (r == -1) {printf("connecting server failed!\n");return -1;}printf("connecting server success!\n");//5.通信char buff[1024];while (1) {memset(buff, 0, 1024);printf("please enter your words: ");gets_s(buff);r = send(clientSocket, buff, strlen(buff), NULL);}return 0;
}

通信效果

多线程模型

同步阻塞的方式只能让服务器服务一个客户端，当服务器没有结束当前客户端的网络I/O时，其他客户端是无法连接服务器的。因此，我们可以使用多线程模型来处理多客户端的请求。

server.cpp

#include <stdio.h>
#include <windows.h>#pragma comment(lib, "ws2_32.lib")SOCKADDR_IN cAddr = { 0 };
int len = sizeof(cAddr);
SOCKET clientSocket[1024];
int count = 0;void communication(int idx) {char buff[1024];int r;while (1) {r = recv(clientSocket[idx], buff, 1023, NULL);if (r > 0) {buff[r] = 0;printf("%d:%s\n", idx, buff);//广播数据for (int i = 0; i < count; i++) {send(clientSocket[i], buff, strlen(buff), NULL);}}}
}int main()
{//1. 请求协议版本WSADATA wsaData;WSAStartup(MAKEWORD(2, 2), &wsaData);if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) {printf("request failed!\n");return -1;}printf("request protocol success!\n");//2. 创建SocketSOCKET serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (serverSocket == SOCKET_ERROR) {printf("create failed!\n");WSACleanup();return -2;}printf("create socket success!\n");//3.创建协议族SOCKADDR_IN addr = { 0 };addr.sin_family = AF_INET; //协议版本addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.127");addr.sin_port = htons(10086);//0-65535 10000左右//4.绑定int r = bind(serverSocket, (sockaddr*)&addr, sizeof addr);if (-1 == r) {printf("bind failed!\n");closesocket(serverSocket);WSACleanup();return -2;}printf("bind success!\n");//5.监听r = listen(serverSocket, 10);if (-1 == r) {printf("listen failed!\n");closesocket(serverSocket);WSACleanup();return -2;}printf("listen success!\n");//6.等待客户端连接    阻塞   while (1) {clientSocket[count] = accept(serverSocket, (sockaddr*)&cAddr, &len);if (SOCKET_ERROR == clientSocket[count]) {printf("serverd failed!\n");closesocket(serverSocket);WSACleanup();return -2;}printf("one client(%s) has connected server!\n", inet_ntoa(cAddr.sin_addr));CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)communication, (char*)count, NULL, NULL);count++;}//7.通信char buff[1024];while (1) {r = recv(clientSocket[count], buff, 1023, NULL);if (r > 0) {buff[r] = 0; // 添加'\0'printf(">>%s\n", buff);}}return 0;
}

client.cpp

#include <stdio.h>#include <graphics.h> //easyX#pragma comment(lib, "ws2_32.lib")SOCKET clientSocket;
HWND hWnd;int count = 0;void received() {char recvBuff[1024];int r;while (1) {r = recv(clientSocket, recvBuff, 1023, NULL);if (r > 0) {recvBuff[r] = 0;outtextxy(0, count * 20, recvBuff);count++;}}
}int main()
{initgraph(300, 400, SHOWCONSOLE);//1. 请求协议版本WSADATA wsaData;WSAStartup(MAKEWORD(2, 2), &wsaData);if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) {printf("request failed!\n");return -1;}printf("request protocol success!\n");//2. 创建SocketclientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (clientSocket == SOCKET_ERROR) {printf("create failed!\n");WSACleanup();return -2;}printf("create socket success!\n");//3.获取服务器协议族SOCKADDR_IN addr = { 0 };addr.sin_family = AF_INET; //协议版本addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.127");addr.sin_port = htons(10086);//0-65535 10000左右//4.连接服务器int r = connect(clientSocket, (sockaddr*)&addr, sizeof addr);if (r == -1) {printf("connecting server failed!\n");return -1;}printf("connecting server success!\n");//5.通信char buff[1024];CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)received, NULL, NULL, NULL);while (1) {memset(buff, 0, 1024);printf("please enter your words: ");gets_s(buff);r = send(clientSocket, buff, strlen(buff), NULL);}return 0;
}

参考文献

Windows网络编程， socket开发
I/O多路复用