Winsock 提供了一個有用的異步I/O模型。利用這個模型，應(yīng)用程序可在一個套接字上，接收以Windows消息為基礎(chǔ)的網(wǎng)絡(luò)事件通知。具體的做法是在建好一個套接字后，調(diào)用WSAAsyncSelect函數(shù)。該模型最早出現(xiàn)于Winsock的1.1版本中，用于幫助應(yīng)用程序開發(fā)者面向一些早期的16位 Windows平臺（如Windows for Workgroups），適應(yīng)其“落后”的多任務(wù)消息環(huán)境。應(yīng)用程序仍可從這種模型中得到好處，特別是它們用一個標(biāo)準(zhǔn)的Windows例程（常稱為 "WndProc"），對窗口消息進(jìn)行管理的時候。該模型亦得到了Microsoft Foundation Class（微軟基本類，MFC）對象CSocket的采納。（節(jié)選自《Windows網(wǎng)絡(luò)編程》第八章)
還是先貼出代碼，然后做詳細(xì)解釋：
#include
#include
#define PORT 5150
#define MSGSIZE 1024
#define WM_SOCKET WM_USER+0
#pragma comment(lib, "ws2_32.lib")
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = _T("AsyncSelect Model");
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass(&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName, // window class name
TEXT ("AsyncSelect Model"), // window caption
WS_OVERLAPPEDWINDOW, // window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
CW_USEDEFAULT, // initial x size
CW_USEDEFAULT, // initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL) ; // creation parameters
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg) ;
DispatchMessage(&msg) ;
}
return msg.wParam;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
WSADATA wsd;
static SOCKET sListen;
SOCKET sClient;
SOCKADDR_IN local, client;
int ret, iAddrSize = sizeof(client);
char szMessage[MSGSIZE];
switch (message)
{
case WM_CREATE:
// Initialize Windows Socket library
WSAStartup(0x0202, &wsd);
// Create listening socket
sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
// Bind
local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
local.sin_family = AF_INET;
local.sin_port = htons(PORT);
bind(sListen, (struct sockaddr *)&local, sizeof(local));
// Listen
listen(sListen, 3);
// Associate listening socket with FD_ACCEPT event
WSAAsyncSelect(sListen, hwnd, WM_SOCKET, FD_ACCEPT);
return 0;
case WM_DESTROY:
closesocket(sListen);
WSACleanup();
PostQuitMessage(0);
return 0;
case WM_SOCKET:
if (WSAGETSELECTERROR(lParam))
{
closesocket(wParam);
break;
}
switch (WSAGETSELECTEVENT(lParam))
{
case FD_ACCEPT:
// Accept a connection from client
sClient = accept(wParam, (struct sockaddr *)&client, &iAddrSize);
// Associate client socket with FD_READ and FD_CLOSE event
WSAAsyncSelect(sClient, hwnd, WM_SOCKET, FD_READ | FD_CLOSE);
break;
case FD_READ:
ret = recv(wParam, szMessage, MSGSIZE, 0);
if (ret == 0 || ret == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET)
{
closesocket(wParam);
}
else
{
szMessage[ret] = ’\0’;
send(wParam, szMessage, strlen(szMessage), 0);
}
break;
case FD_CLOSE:
closesocket(wParam);
break;
}
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
WSAAsyncSelect是最簡單的一種Winsock I/O模型（之所以說它簡單是因為一個主線程就搞定了）。使用Raw Windows API寫過窗口類應(yīng)用程序的人應(yīng)該都能看得懂。這里，我們需要做的僅僅是：
1.在WM_CREATE消息處理函數(shù)中，初始化Windows Socket library，創(chuàng)建監(jiān)聽套接字，綁定，監(jiān)聽，并且調(diào)用WSAAsyncSelect函數(shù)表示我們關(guān)心在監(jiān)聽套接字上發(fā)生的FD_ACCEPT事件；
2.自定義一個消息WM_SOCKET，一旦在我們所關(guān)心的套接字（監(jiān)聽套接字和客戶端套接字）上發(fā)生了某個事件，系統(tǒng)就會調(diào)用WndProc并且message參數(shù)被設(shè)置為WM_SOCKET；
3.在WM_SOCKET的消息處理函數(shù)中，分別對FD_ACCEPT、FD_READ和FD_CLOSE事件進(jìn)行處理；
4.在窗口銷毀消息(WM_DESTROY)的處理函數(shù)中，我們關(guān)閉監(jiān)聽套接字，清除Windows Socket library
下面這張用于WSAAsyncSelect函數(shù)的網(wǎng)絡(luò)事件類型表可以讓你對各個網(wǎng)絡(luò)事件有更清楚的認(rèn)識：
FD_READ
應(yīng)用程序想要接收有關(guān)是否可讀的通知，以便讀入數(shù)據(jù)
FD_WRITE
應(yīng)用程序想要接收有關(guān)是否可寫的通知，以便寫入數(shù)據(jù)
FD_OOB
應(yīng)用程序想接收是否有帶外（OOB）數(shù)據(jù)抵達(dá)的通知
FD_ACCEPT
應(yīng)用程序想接收與進(jìn)入連接有關(guān)的通知
FD_CONNECT
應(yīng)用程序想接收與一次連接或者多點join操作完成的通知
FD_CLOSE
應(yīng)用程序想接收與套接字關(guān)閉有關(guān)的通知
FD_QOS
應(yīng)用程序想接收套接字“服務(wù)質(zhì)量”（QoS）發(fā)生更改的通知
FD_GROUP_QOS
應(yīng)用程序想接收套接字組“服務(wù)質(zhì)量”發(fā)生更改的通知（現(xiàn)在沒什么用處，為未來套接字組的使用保留）
FD_ROUTING_INTERFACE_CHANGE
應(yīng)用程序想接收在指定的方向上，與路由接口發(fā)生變化的通知
FD_ADDRESS_LIST_CHANGE
應(yīng)用程序想接收針對套接字的協(xié)議家族，本地地址列表發(fā)生變化的通知
還是先貼出代碼，然后做詳細(xì)解釋：
#include
#include
#define PORT 5150
#define MSGSIZE 1024
#define WM_SOCKET WM_USER+0
#pragma comment(lib, "ws2_32.lib")
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = _T("AsyncSelect Model");
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass(&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName, // window class name
TEXT ("AsyncSelect Model"), // window caption
WS_OVERLAPPEDWINDOW, // window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
CW_USEDEFAULT, // initial x size
CW_USEDEFAULT, // initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL) ; // creation parameters
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg) ;
DispatchMessage(&msg) ;
}
return msg.wParam;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
WSADATA wsd;
static SOCKET sListen;
SOCKET sClient;
SOCKADDR_IN local, client;
int ret, iAddrSize = sizeof(client);
char szMessage[MSGSIZE];
switch (message)
{
case WM_CREATE:
// Initialize Windows Socket library
WSAStartup(0x0202, &wsd);
// Create listening socket
sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
// Bind
local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
local.sin_family = AF_INET;
local.sin_port = htons(PORT);
bind(sListen, (struct sockaddr *)&local, sizeof(local));
// Listen
listen(sListen, 3);
// Associate listening socket with FD_ACCEPT event
WSAAsyncSelect(sListen, hwnd, WM_SOCKET, FD_ACCEPT);
return 0;
case WM_DESTROY:
closesocket(sListen);
WSACleanup();
PostQuitMessage(0);
return 0;
case WM_SOCKET:
if (WSAGETSELECTERROR(lParam))
{
closesocket(wParam);
break;
}
switch (WSAGETSELECTEVENT(lParam))
{
case FD_ACCEPT:
// Accept a connection from client
sClient = accept(wParam, (struct sockaddr *)&client, &iAddrSize);
// Associate client socket with FD_READ and FD_CLOSE event
WSAAsyncSelect(sClient, hwnd, WM_SOCKET, FD_READ | FD_CLOSE);
break;
case FD_READ:
ret = recv(wParam, szMessage, MSGSIZE, 0);
if (ret == 0 || ret == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET)
{
closesocket(wParam);
}
else
{
szMessage[ret] = ’\0’;
send(wParam, szMessage, strlen(szMessage), 0);
}
break;
case FD_CLOSE:
closesocket(wParam);
break;
}
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
WSAAsyncSelect是最簡單的一種Winsock I/O模型（之所以說它簡單是因為一個主線程就搞定了）。使用Raw Windows API寫過窗口類應(yīng)用程序的人應(yīng)該都能看得懂。這里，我們需要做的僅僅是：
1.在WM_CREATE消息處理函數(shù)中，初始化Windows Socket library，創(chuàng)建監(jiān)聽套接字，綁定，監(jiān)聽，并且調(diào)用WSAAsyncSelect函數(shù)表示我們關(guān)心在監(jiān)聽套接字上發(fā)生的FD_ACCEPT事件；
2.自定義一個消息WM_SOCKET，一旦在我們所關(guān)心的套接字（監(jiān)聽套接字和客戶端套接字）上發(fā)生了某個事件，系統(tǒng)就會調(diào)用WndProc并且message參數(shù)被設(shè)置為WM_SOCKET；
3.在WM_SOCKET的消息處理函數(shù)中，分別對FD_ACCEPT、FD_READ和FD_CLOSE事件進(jìn)行處理；
4.在窗口銷毀消息(WM_DESTROY)的處理函數(shù)中，我們關(guān)閉監(jiān)聽套接字，清除Windows Socket library
下面這張用于WSAAsyncSelect函數(shù)的網(wǎng)絡(luò)事件類型表可以讓你對各個網(wǎng)絡(luò)事件有更清楚的認(rèn)識：
FD_READ
應(yīng)用程序想要接收有關(guān)是否可讀的通知，以便讀入數(shù)據(jù)
FD_WRITE
應(yīng)用程序想要接收有關(guān)是否可寫的通知，以便寫入數(shù)據(jù)
FD_OOB
應(yīng)用程序想接收是否有帶外（OOB）數(shù)據(jù)抵達(dá)的通知
FD_ACCEPT
應(yīng)用程序想接收與進(jìn)入連接有關(guān)的通知
FD_CONNECT
應(yīng)用程序想接收與一次連接或者多點join操作完成的通知
FD_CLOSE
應(yīng)用程序想接收與套接字關(guān)閉有關(guān)的通知
FD_QOS
應(yīng)用程序想接收套接字“服務(wù)質(zhì)量”（QoS）發(fā)生更改的通知
FD_GROUP_QOS
應(yīng)用程序想接收套接字組“服務(wù)質(zhì)量”發(fā)生更改的通知（現(xiàn)在沒什么用處，為未來套接字組的使用保留）
FD_ROUTING_INTERFACE_CHANGE
應(yīng)用程序想接收在指定的方向上，與路由接口發(fā)生變化的通知
FD_ADDRESS_LIST_CHANGE
應(yīng)用程序想接收針對套接字的協(xié)議家族，本地地址列表發(fā)生變化的通知