先上一些多线程需要使用的函数定义：

复制代码 代码如下:
DWORD WINAPI ProcessClientRequests(LPVOID lpParam) //新线程将会执行的函数定义
{
return 0;
}

HANDLE handler=CreateThread(NULL, 0, ProcessClientRequests, &clientsocket, 0, NULL); //这里比较简单，&clientsocket是个指针，是从主线程传入新线程的参数

WaitForMultipleObjects(MAXCLIENTS, threads, TRUE, INFINITE); //用来阻塞主线程，直到所有创建的子线程都完成任务为止，才继续执行后面的代码

for(int i=0;i<MAXCLIENTS; i++)
{
CloseHandle(threads[i]); //创建的每个子线程的HANDLE都会被保存在HANDLE数组中，这个函数用于关闭各个handle所对应的线程空间
}

服务器端程序

主线程代码如下：

复制代码 代码如下:
#define MAXCLIENTS 3 //宏定义，最多3个客户端连接

int main()
{
WSADATA wsaData;
WSAStartup(MAKEWORD(2, 2), &wsaData);
HANDLE threads[MAXCLIENTS];

SOCKET s=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

sockaddr_in sockaddr;
sockaddr.sin_family=PF_INET;
sockaddr.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");
sockaddr.sin_port=htons(9000);
bind(s, (SOCKADDR*)&sockaddr, sizeof(SOCKADDR));

listen(s, 1);

printf("listening on port [%d].\n", 9000);

int existingClientCount=0;
while(TRUE)
{
SOCKADDR clientAddr;
int size=sizeof(SOCKADDR);

SOCKET clientsocket;
clientsocket=accept(s, &clientAddr, &size);
printf("***SYS*** New client touched.\n");

if(existingClientCount<MAXCLIENTS) //判断是否已经超出最大连接数了
{
threads[existingClientCount++]=CreateThread(NULL, 0, ProcessClientRequests, &clientsocket, 0, NULL); //启动新线程，并且将socket传入
}
else
{
char* msg="Exceeded Max incoming requests, will refused this connect!\r\n";
send(clientsocket, msg, strlen(msg)+sizeof(char), NULL); //发送拒绝连接消息给客户端
printf("***SYS*** REFUSED.\n");
closesocket(clientsocket); //释放资源
break;
}
}

printf("Maximize clients occurred for d%.\r\n", MAXCLIENTS);

WaitForMultipleObjects(MAXCLIENTS, threads, TRUE, INFINITE); //等待所有子线程，直到完成为止

closesocket(s);
for(int i=0;i<MAXCLIENTS; i++)
{
CloseHandle(threads[i]); //清理线程资源
}

WSACleanup();

printf("Cleared all.\r\n");

getchar();

exit(0);
}

子线程函数定义

复制代码 代码如下:
DWORD WINAPI ProcessClientRequests(LPVOID lpParam)
{
SOCKET* clientsocket=(SOCKET*)lpParam; //这里需要强制转换，注意：指针类型的

char* msg="Hello, my client.\r\n";
send(*clientsocket, msg, strlen(msg)+sizeof(char), NULL);
printf("***SYS*** HELLO.\n");

while(TRUE)
{
char buffer[MAXBYTE]={0};
recv(*clientsocket, buffer, MAXBYTE, NULL);
if(strcmp(buffer, "exit")==0)
{
char* msg_bye="Bye.\r\n";
send(*clientsocket, msg_bye, strlen(msg_bye)+sizeof(char), NULL);
break;
}
printf("***Client*** %s\n", buffer);
}

closesocket(*clientsocket);

return 0;
}