Socket套接字编程（二）——UDP编程

TCP编程完了,下面轮到UDP了，这个是面向无连接的，更加简单。

先熟悉下流程：

UDP型套接字：

服务器端（接收端）程序：
1、创建套接字（socket）。
2、将套接字绑定到一个本地地址和端口上（bind）。
3、等待接收数据（recvfrom）。
4、关闭套接字。

客户端（发送端）程序：
1、创建套接字（socket）。
2、向服务器发送数据（sendto）。
3、关闭套接字。

下面继续直接上代码：

服务器端

#include <winsock2.h>#include <iostream>using namespace std;#pragma comment(lib, "WS2_32.lib")int StartUDPSrv(){#pragma region 初始化套接字库WSADATA wsaData;int iResult = WSAStartup(MAKEWORD(1, 1), &wsaData); //版本1.1if (NO_ERROR != iResult){cout<<"Error at WSAStartup()/n";return -1;}if ( LOBYTE( wsaData.wVersion ) != 1 ||HIBYTE( wsaData.wVersion ) != 1 ) {WSACleanup( );return -1;}//如果不是1.1的则退出#pragma endregion 初始化套接字库#pragma region 创建套接字// Create a SOCKET for listening for incoming connection requestsSOCKET socketSrv = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);if (INVALID_SOCKET == socketSrv) {cout<<"Error at socket():/n"<< WSAGetLastError();WSACleanup();return -1;}#pragma endregion 创建套接字#pragma region 绑定套接字int err;SOCKADDR_IN addrSrv;addrSrv.sin_family = AF_INET;addrSrv.sin_addr.S_un.S_addr = htonl(INADDR_ANY);addrSrv.sin_port= htons(8086);err = bind(socketSrv, (SOCKADDR*) &addrSrv, sizeof(addrSrv));if (SOCKET_ERROR == err){cout<<"Error at Bind!/n"<< WSAGetLastError();closesocket(socketSrv);WSACleanup();return -1;}#pragma endregion 绑定套接字#pragma region 等待接收SOCKADDR_IN addrClient;int len = sizeof(sockaddr);char recvBuf[100];while (1){memset(recvBuf, '*', sizeof(char)*100); //置空接受数组err = recvfrom(socketSrv, recvBuf, strlen(recvBuf), 0, (SOCKADDR*) &addrClient, &len);int len2 = strlen(recvBuf);if (SOCKET_ERROR == err){cout<<"Error at RecvFrom Srv!/n"<< WSAGetLastError();/*closesocket(socketSrv);WSACleanup();return -1;*/}cout<<recvBuf<<endl;/************************************************************************//* 发送数据 *//************************************************************************/char sendBuf[100];sprintf_s(sendBuf, 100, "Welcome %s to This UDP Service!", inet_ntoa(addrClient.sin_addr));err = sendto(socketSrv, sendBuf, strlen(sendBuf)+1, 0, (SOCKADDR*) &addrClient, sizeof(SOCKADDR));if (SOCKET_ERROR == err){cout<<"Error at SrvSendto!/n"<< WSAGetLastError();closesocket(socketSrv);WSACleanup();return -1;}}#pragma endregion 等待接收closesocket(socketSrv);WSACleanup();return 1;}int main(void){StartUDPSrv();//system("pause");return 0;}

客户端代码：

 

#include <winsock2.h>#include <iostream>using namespace std;#pragma comment(lib, "WS2_32.lib")int CallUDPClient(){#pragma region 初始化套接字库WSADATA wsaData;int iResult = WSAStartup(MAKEWORD(1, 1), &wsaData); //版本1.1if (NO_ERROR != iResult){cout<<"Error at WSAStartup()/n";return -1;}if ( LOBYTE( wsaData.wVersion ) != 1 ||HIBYTE( wsaData.wVersion ) != 1 ) {WSACleanup( );return -1;}//如果不是1.1的则退出#pragma endregion 初始化套接字库#pragma region 创建套接字// Create a SOCKET for listening for incoming connection requestsSOCKET socketClient = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);if (INVALID_SOCKET == socketClient) {cout<<"Error at socket():/n"<< WSAGetLastError();WSACleanup();return -1;}#pragma endregion 创建套接字#pragma region 发送数据SOCKADDR_IN addrSrv;addrSrv.sin_family = AF_INET;addrSrv.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");addrSrv.sin_port = htons(8086);int len = sizeof(SOCKADDR);//char sendBuf[100] = "Hello! This is UDP Client!";char sendBuf[100];gets_s(sendBuf);int err = sendto(socketClient, sendBuf, strlen(sendBuf)+1, 0, (SOCKADDR*) &addrSrv, len);if (SOCKET_ERROR == err){cout<<"Error at Sendto Client:/n"<< WSAGetLastError();closesocket(socketClient);WSACleanup();return -1;}#pragma endregion 发送数据#pragma region 接受数据char recvBuf[100];err = recvfrom(socketClient, recvBuf, strlen(recvBuf), 0, (SOCKADDR*)&addrSrv, &len);if (SOCKET_ERROR == err){cout<<"Error at RecvFrom Client:/n"<< WSAGetLastError();closesocket(socketClient);WSACleanup();return -1;}cout<<recvBuf<<endl;#pragma endregion 接受数据closesocket(socketClient);WSACleanup();return 1;}int main(){CallUDPClient();system("pause"); return 0;}

 

测试下，代码没多大问题。

 

但现在我们的代码存在和TCP的时候同样的一个问题，我们设置的服务器端接受数据的大小为1024；但如果大于这个怎么办呢？嘿嘿，下回分解。