By 浮茗

Updated:

Contents
  1. 1. 准备
  • include
    1. 1. 代码
      1. 1.1. 客户端
      2. 1.2. 服务器端
    2. 2. 代码解析
      1. 2.1. 初始化部分
      2. 2.2. 监听准备
      3. 2.3. 发送数据
      4. 2.4. 接收数据
      5. 2.5. 善后处理

    • 以控制台下实现为例子

    准备

    include<Winsock2.h>

    需要在项目中添加依赖项：Ws2_32.lib

    代码

    此代码实现的功能是服务器端发送数据，客户端连接上服务器端并监听服务器端发送来的数据。

    客户端

    #include "stdafx.h"
#include<Winsock2.h>
void _tmain(int argc, _TCHAR* argv[])
{
 //加载socket动态链接库
 WORD wVersionRequested;
 WSADATA wsaData;
 int err;
wVersionRequested = MAKEWORD( 1, 1 );
err = WSAStartup( wVersionRequested, &wsaData );
 if ( err != 0 ) {
  return;
 }
if ( LOBYTE( wsaData.wVersion ) != 1 ||
   HIBYTE( wsaData.wVersion ) != 1 ) {
  WSACleanup( );
  return; 
 }
 //创建客户端套接字
    SOCKET client=socket(AF_INET,SOCK_STREAM,0);//流式套接字。（数据报套接字，原套接字）
 SOCKADDR_IN svr_addr_in;//保存服务器端的地址信息
 svr_addr_in.sin_family=AF_INET;//代表TCP/IP协议族
 //inet_addr()把字符串变成无符号的长整型。获取服务器地址.0.0.1：本机做服务器,127.0.0.1是服务器的ip地址
 svr_addr_in.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");
 //htons本函数将一个位数从主机字节顺序转换成网络字节顺序，该端口号要与服务器的端口号相同
 svr_addr_in.sin_port=htons(6000);
 while(connect(client,(sockaddr*)&svr_addr_in,sizeof(svr_addr_in))!=0);//链接服务器,等于表示连上服务器
 char b[1024];
 for(int i=0;;i++)
 {
 recv(client,b,sizeof(b),0);//客户端接受文件
  printf("%s",b);
 }
 closesocket(client);//关闭客户端套接字
 WSACleanup();//卸载winsock动态链接库
}

    服务器端

    #include "stdafx.h"
#include<Winsock2.h>
void  _tmain(int argc, _TCHAR* argv[])
{
 //加载socket动态链接库
 WORD wVersionRequested;
 WSADATA wsaData;
 int err;
wVersionRequested = MAKEWORD( 1, 1 );
err = WSAStartup( wVersionRequested, &wsaData );
 if ( err != 0 ) {
  return;
 }
if ( LOBYTE( wsaData.wVersion ) != 1 ||
   HIBYTE( wsaData.wVersion ) != 1 ) {
  WSACleanup( );
  return; 
 }
 SOCKET svr=socket(AF_INET,SOCK_STREAM,0);
 SOCKADDR_IN svr_addr_in;//创建一个服务器地址结构体，用于保存服务器的信息
 svr_addr_in.sin_family=AF_INET;//协议家族
 svr_addr_in.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");//htonl(INADDR_ANY);//获取当前机子网卡ip地址
 svr_addr_in.sin_port=htons(6000);//设置端口地址
    bind(svr,(sockaddr*)&svr_addr_in,sizeof(SOCKADDR_IN));//将socket绑定到本地机地址上面
 //把服务器socket设置为监听socket，同时能监听个client客服
 listen(svr,5);
    SOCKADDR_IN client_addr_in;//用于保存客户端的信息
 int len=sizeof(SOCKADDR_IN);
    SOCKET client=accept(svr,(sockaddr*)&client_addr_in,&len);//等待（接受）客户端请求到来
 char b[1024]="ss";
 for(int i=0;;i++)
 {
 send(client,b,sizeof(b),0);//向服务器发送数据
 //system("pause"):
 }
 closesocket(client);//关闭客户端套接字
 closesocket(svr);//关闭服务器套接字
    WSACleanup();//卸载socket链接库
 return ;
}

    代码解析

    初始化部分

    WORD wVersionRequested MAKEWORD( 1, 1 );
 WSADATA wsaData;
int err= WSAStartup( wVersionRequested, &wsaData );
    MAKEWORD(a,b)是一个宏，定义如下： 
    #defineMAKEWORD(a,b)((WORD)(((BYTE)(((DWORD_PTR)(a))&0xff))|((WORD)((BYTE)(((DWORD_PTR)(b))&0xff)))<<8))
    目的是将两个单字节拼成一个双字节，比如(1,1)会被拼成0x0101. WSADATA为结构体，用于存储socket的内容，定义如下： 
    typedef struct WSAData {
        WORD                    wVersion;
        WORD                    wHighVersion;
#ifdef _WIN64
        unsigned short          iMaxSockets;
        unsigned short          iMaxUdpDg;
        char FAR *              lpVendorInfo;
        char                    szDescription[WSADESCRIPTION_LEN+1];
        char                    szSystemStatus[WSASYS_STATUS_LEN+1];
#else
        char                    szDescription[WSADESCRIPTION_LEN+1];
        char                    szSystemStatus[WSASYS_STATUS_LEN+1];
        unsigned short          iMaxSockets;
        unsigned short          iMaxUdpDg;
        char FAR *              lpVendorInfo;
#endif
} WSADATA
    函数 
    int WSAStartup(
  __in          WORD wVersionRequested,
  __out         LPWSADATA lpWSAData
);
    The**WSAStartup**functioninitiatesuseoftheWinsockDLLbyaprocess. **Parameters** **wVersionRequested** ThehighestversionofWindowsSocketsspecificationthatthecallercanuse.Thehigh-orderbytespecifiestheminorversionnumber;thelow-orderbytespecifiesthemajorversionnumber. **ReturnValue** Ifsuccessful,the**WSAStartup**functionreturnszero.Otherwise,itreturnsoneoftheerrorcodeslistedbelow.TheWSAStartupfunctiondirectlyreturnstheextendederrorcodeinthereturnvalueforthisfunction.Acalltothe[**WSAGetLastError**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/wsagetlasterror_2.htm)functionisnotneededandshouldnotbeused.
    **Errorcode** **Meaning**
    [**WSASYSNOTREADY**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/windows_sockets_error_codes_2.htm#winsock.wsasysnotready_2) Theunderlyingnetworksubsystemisnotreadyfornetworkcommunication.
    [**WSAVERNOTSUPPORTED**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/windows_sockets_error_codes_2.htm#winsock.wsavernotsupported_2) TheversionofWindowsSocketssupportrequestedisnotprovidedbythisparticularWindowsSocketsimplementation.
    [**WSAEINPROGRESS**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/windows_sockets_error_codes_2.htm#winsock.wsaeinprogress_2) AblockingWindowsSockets1.1operationisinprogress.
    [**WSAEPROCLIM**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/windows_sockets_error_codes_2.htm#winsock.wsaeproclim_2) AlimitonthenumberoftaskssupportedbytheWindowsSocketsimplementationhasbeenreached.
    [**WSAEFAULT**](ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/winsock/winsock/windows_sockets_error_codes_2.htm#winsock.wsaefault_2) ThelpWSADataparameterisnotavalidpointer.
    **Requirements**
    **Client** RequiresWindowsVista,WindowsXP,Windows2000Professional,WindowsNTWorkstation,WindowsMe,Windows98,orWindows95.
    **Server** RequiresWindowsServer2008,WindowsServer2003,Windows2000Server,orWindowsNTServer.
    **Header** DeclaredinWinsock2.h.
    **Library** UseWs2_32.lib.
    **DLL** RequiresWs2_32.dll.
    ### 连接准备 
    //创建客户端套接字
    SOCKET client=socket(AF_INET,SOCK_STREAM,0);//流式套接字。（数据报套接字，原套接字）
 SOCKADDR_IN svr_addr_in;//保存服务器端的地址信息
 svr_addr_in.sin_family=AF_INET;//代表TCP/IP协议族
 //inet_addr()把字符串变成无符号的长整型。获取服务器地址.0.0.1：本机做服务器,127.0.0.1是服务器的ip地址
 svr_addr_in.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");
 //htons本函数将一个位数从主机字节顺序转换成网络字节顺序，该端口号要与服务器的端口号相同
 svr_addr_in.sin_port=htons(6000);
 while(connect(client,(sockaddr*)&svr_addr_in,sizeof(svr_addr_in))!=0);//链接服务器,等于表示连上服务器
    SOCKET为重定义变量，原始变量类型为_W64unsignedint. 函数 
    SOCKET WSAAPI socket(
  __in          int af,
  __in          int type,
  __in          int protocol
);
    The**socket**functioncreatesasocketthatisboundtoaspecifictransportserviceprovider. 结构体**SOCKADDR_IN** 
    struct sockaddr_in{
short sin_family;    //Address family (must be AF_INET).
unsigned short sin_port;    //IP port.
struct in_addr sin_addr;    //IP address.
char sin_zero[8];    //Padding to make structure the same size as SOCKADDR.
};
    The**connect**functionestablishesaconnectiontoaspecifiedsocket. 
    int connect(
__in  SOCKET s,    //Descriptor identifying an unconnected socket.
__in  const struct sockaddr* name,//Name of the socket in the sockaddr structure to which the connection should be established.
  __in int namelen    //Length of name, in bytes.
);

    监听准备

    SOCKET svr=socket(AF_INET,SOCK_STREAM,0);
 SOCKADDR_IN svr_addr_in;//创建一个服务器地址结构体，用于保存服务器的信息
 svr_addr_in.sin_family=AF_INET;//协议家族
 svr_addr_in.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");//htonl(INADDR_ANY);//获取当前机子网卡ip地址
 svr_addr_in.sin_port=htons(6000);//设置端口地址
    bind(svr,(sockaddr*)&svr_addr_in,sizeof(SOCKADDR_IN));//将socket绑定到本地机地址上面
 //把服务器socket设置为监听socket，同时能监听个client客服
 listen(svr,5);
    **bind**函数 
    bind(
    IN SOCKET s,
    __in_bcount(namelen) const struct sockaddr FAR * name,
    IN int namelen
    );
    The**listen**functionplacesasocketinastateinwhichitislisteningforanincomingconnection. 
    int listen(
  __in     SOCKET s,    //Descriptor identifying a bound, unconnected socket.
  __in     int backlog    //允许的最多的连接队列
);

    发送数据

        SOCKADDR_IN client_addr_in;//用于保存客户端的信息
 int len=sizeof(SOCKADDR_IN);
    SOCKET client=accept(svr,(sockaddr*)&client_addr_in,&len);//等待（接受）客户端请求到来
 char b[1024]="ss";
 for(int i=0;;i++)
 {
 send(client,b,sizeof(b),0);//向服务器发送数据
 //system("pause"):
 }

    接收数据

    char b[1024];
 for(int i=0;;i++)
 {
 recv(client,b,sizeof(b),0);//客户端接受文件
  printf("%s",b);
 }
    **send**与**recv**函数的参数表都是 
    IN SOCKET s,    // The descriptor that identifies a connected socket.
__out_bcount_part(len, return) __out_data_source(NETWORK) char FAR * buf,
// The buffer for incoming data.
IN int len,// The length, in bytes, of the buf parameter.
IN int flags
//A pointer to flags that influences the behavior of this function. See remarks below.

    善后处理

    closesocket(client);//关闭客户端套接字
closesocket(svr);//关闭服务器套接字
WSACleanup();//卸载winsock动态链接库
    Contents
    1. 1. 准备
  • include
    1. 1. 代码
      1. 1.1. 客户端
      2. 1.2. 服务器端
    2. 2. 代码解析
      1. 2.1. 初始化部分
      2. 2.2. 监听准备
      3. 2.3. 发送数据
      4. 2.4. 接收数据
      5. 2.5. 善后处理