異步方式調用WinInet

轉自：http://www.cppblog.com/huyutian/articles/122994.html

 

異步方式調用WinInet

關於WinInet的異步模式，微軟給過很多例子，但我覺得下面這個是比較好理解的。
原文地址，代碼貼出來，有些細節部分還要自己慢慢體會。
我在調試過程中，還參照了以下一些鏈接
關於GetLastError返回1201（ERROR_INTERNET_INCORRECT_HANDLE_STATE）9錯誤的解決辦法請參見下面兩個鏈接
http://support.genopro.com/Topic14017-59-1.aspx
http://support.microsoft.com/kb/177190
這是微軟wininet的一個bug，僅當大 POST請求包要發送時，使用 HttpSendRequestEx。其他時候使用HttpSendRequest。防止12019錯誤

WinInet 錯誤代碼可參照這裏 http://support.microsoft.com/kb/193625

  1#include<windows.h>
  2#include<wininet.h>
  3#include<iostream.h>
  4
  5HANDLE hConnectedEvent, hRequestOpenedEvent, hRequestCompleteEvent;
  6HINTERNET hInstance, hConnect, hRequest;
  7char *lpszUrl, *lpszServer;
  8
  9BOOL bAllDone = FALSE;
10BOOL bVerbose = FALSE;
11
12void __stdcall Callback(HINTERNET hInternet,
13              DWORD dwContext,
14              DWORD dwInternetStatus,
15              LPVOID lpStatusInfo,
16              DWORD dwStatusInfoLen);
17
18void main(int argc, char *argv[])
19{
20    if (argc != 3)
21    {
22        if ((argc == 4) && (argv[3][0] == 'v'))
23            bVerbose = TRUE;
24        else
25        {
26            cout << "Usage: asynchttp <server> <url> [v]" << endl;
27            cout << "   <server> is the hostname of the http server" << endl;
28            cout << "   <url> is the url of the object you are requesting (without the hostname)" << endl;
29            cout << "   'v' for verbose output" << endl << endl;
30            cout << "   Example: asynchttp www.domain.com /docs/readme.htm v" << endl;
31            return;
32        }
33    }
34
35    lpszServer = argv[1];
36    lpszUrl = argv[2];
37
38    hConnectedEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
39    hRequestOpenedEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
40    hRequestCompleteEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
41
42    hInstance = InternetOpen("asynchttp",
43                             INTERNET_OPEN_TYPE_PRECONFIG,
44                             NULL,
45                             NULL,
46                             INTERNET_FLAG_ASYNC); // ASYNC Flag
47
48    if (hInstance == NULL)
49    {
50        cout << "InternetOpen failed, error " << GetLastError();
51        return;
52    }
53
54    // Setup callback function
55    if (InternetSetStatusCallback(hInstance,
56                                  (INTERNET_STATUS_CALLBACK)&Callback) == INTERNET_INVALID_STATUS_CALLBACK)
57    {
58        cout << "InternetSetStatusCallback failed, error " << GetLastError();
59        return;
60    }
61
62    // First call that will actually complete asynchronously even
63    // though there is no network traffic
64    hConnect = InternetConnect(hInstance,
65                               lpszServer,
66                               INTERNET_DEFAULT_HTTP_PORT,
67                               NULL,
68                               NULL,
69                               INTERNET_SERVICE_HTTP,
70                               0,
71                               1); // Connection handle's Context
72    if (hConnect == NULL)
73    {
74        if (GetLastError() != ERROR_IO_PENDING)
75        {
76            cout << "InternetConnect failed, error " << GetLastError();
77            return;
78        }
79        // Wait until we get the connection handle
80        WaitForSingleObject(hConnectedEvent, INFINITE);
81    }
82
83
84    // Open the request
85    hRequest = HttpOpenRequest(hConnect,
86                               "GET",
87                               lpszUrl,
88                               NULL,
89                               NULL,
90                               NULL,
91                               INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE,
92                               2);  // Request handle's context
93    if (hRequest == NULL)
94    {
95        if (GetLastError() != ERROR_IO_PENDING)
96        {
97            cout << "HttpOpenRequest failed, error " << GetLastError();
98            return;
99        }
100        // Wait until we get the request handle
101        WaitForSingleObject(hRequestOpenedEvent, INFINITE);
102    }
103
104    if (!HttpSendRequest(hRequest,
105                         NULL,
106                         0,
107                         NULL,
108                         0))
109    {
110        if (GetLastError() != ERROR_IO_PENDING)
111        {
112            cout << "HttpSendRequest failed, error " << GetLastError();
113            return;
114        }
115    }
116   
117    if (bVerbose)
118    {
119        cout << "HttpSendRequest called successfully" << endl;
120        cout.flush();
121    }
122
123    WaitForSingleObject(hRequestCompleteEvent, INFINITE);
124
125    cout << "------------------- Read the response -------------------" << endl;
126    char lpReadBuff[256];
127
128    do
129    {
130        INTERNET_BUFFERS InetBuff;
131        FillMemory(&InetBuff, sizeof(InetBuff), 0);
132        InetBuff.dwStructSize = sizeof(InetBuff);
133        InetBuff.lpvBuffer = lpReadBuff;
134        InetBuff.dwBufferLength = sizeof(lpReadBuff) - 1;
135       
136        if (bVerbose)
137        {
138            cout << "Calling InternetReadFileEx" << endl;
139            cout.flush();
140        }
141
142        if (!InternetReadFileEx(hRequest,
143                              &InetBuff,
144                              0, 2))
145        {
146            if (GetLastError() == ERROR_IO_PENDING)
147            {
148                if (bVerbose)
149                {
150                    cout << "Waiting for InternetReadFileEx to complete" << endl;
151                    cout.flush();
152                }
153                WaitForSingleObject(hRequestCompleteEvent, INFINITE);
154            }
155            else
156            {
157                cout << "InternetReadFileEx failed, error " << GetLastError();
158                cout.flush();
159                return;
160            }
161        }
162
163        lpReadBuff[InetBuff.dwBufferLength] = 0;
164        cout << lpReadBuff;
165        cout.flush();
166
167        if (InetBuff.dwBufferLength == 0)
168            bAllDone = TRUE;
169
170    } while (bAllDone == FALSE);
171
172    cout << endl << endl << "------------------- Request Complete ----------------" << endl;
173
174}
175
176void __stdcall Callback(HINTERNET hInternet,
177              DWORD dwContext,
178              DWORD dwInternetStatus,
179              LPVOID lpStatusInfo,
180              DWORD dwStatusInfoLen)
181{
182    if (bVerbose)
183    {
184        cout << "Callback dwInternetStatus: " << dwInternetStatus << " Context: " << dwContext << endl;
185        cout.flush();
186    }
187
188    switch(dwContext)
189    {
190    case 1: // Connection handle
191        if (dwInternetStatus == INTERNET_STATUS_HANDLE_CREATED)
192        {
193            INTERNET_ASYNC_RESULT *pRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
194            hConnect = (HINTERNET)pRes->dwResult;
195            if (bVerbose)
196            {
197                cout << "Connect handle created" << endl;
198                cout.flush();
199            }
200            SetEvent(hConnectedEvent);
201        }
202        break;
203    case 2: // Request handle
204        switch(dwInternetStatus)
205        {
206        case INTERNET_STATUS_HANDLE_CREATED:
207            {
208                INTERNET_ASYNC_RESULT *pRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
209                hRequest = (HINTERNET)pRes->dwResult;
210                if (bVerbose)
211                {
212                    cout << "Request handle created" << endl;
213                    cout.flush();
214                }
215                SetEvent(hRequestOpenedEvent);
216            }
217            break;
218        case INTERNET_STATUS_REQUEST_SENT:
219            {
220                DWORD *lpBytesSent = (DWORD*)lpStatusInfo;
221                if (bVerbose)
222                {
223                    cout << "Bytes Sent: " << *lpBytesSent << endl;
224                    cout.flush();
225                }
226            }
227            break;
228        case INTERNET_STATUS_REQUEST_COMPLETE:
229            {
230                INTERNET_ASYNC_RESULT *pAsyncRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
231                if (bVerbose)
232                {
233                    cout << "Function call finished" << endl;
234                    cout << "dwResult: " << pAsyncRes->dwResult << endl;
235                    cout << "dwError:  " << pAsyncRes->dwError << endl;
236                    cout.flush();
237                }
238                SetEvent(hRequestCompleteEvent);
239            }
240            break;
241        case INTERNET_STATUS_RECEIVING_RESPONSE:
242            if (bVerbose)
243            {
244                cout << "Receiving Response" << endl;
245                cout.flush();
246            }
247            break;
248        case INTERNET_STATUS_RESPONSE_RECEIVED:
249            {
250                DWORD *dwBytesReceived = (DWORD*)lpStatusInfo;
251                if (*dwBytesReceived == 0)
252                    bAllDone = TRUE;
253                if (bVerbose)
254                {
255                    cout << "Received " << *dwBytesReceived << endl;
256                    cout.flush();
257                }
258            }
259
260        }
261
262    }
263
264}
265