在WinInet編程中，同步的使用方法如下：
InternetOpen->InternetOpenUrl->HttpQueryInfo->InternetReadFile->InternetCloseHandle;在InternetOpenUrl和InternetReadFile時會導致程序阻塞，知道操作完成，同步的好處就是比較簡單，調試方便。
異步的使用方法如下：
1)InternetOpen，需指定是異步；
2)InternetSetStatusCallback,設置回調；
3)InternetOpenUrl,需指定回調參數；
4)WaitForSingObject或WaitForMultipleObjects，接收信號量；
5)HttpQueryInfo；
6)InternetReadFileEx，需指定回調參數(CE或mobile下是InternetReadFileExA)；
7)WaitForSingObject或WaitForMultipleObjects，接收信號量；
8)InternetSetStatusCallback,卸載回調；
9)InternetCloseHandle。
異步比同步要復雜了不少，重點在于回調函數。在回調中，系統會及時返回各種系統定義的HTTP消息，我們根據這些消息來設置某些信號量。在WaitForSingObject或WaitForMultipleObjects里，等待這些信號(當然也可以等待用戶的取消動作)。當有正確的信號返回時，繼續往下的操作。下面一個例子代碼：上面的理論同樣適用于wince或windows mobile平臺
#include<windows.h>
#include<wininet.h>
#include<iostream.h>
DWORD dwNumKSent;
DWORD dwNumKToSend;
DWORD dwNumBytesComplete = 0;
char lpOutBuf[1024];
HANDLE hConnectedEvent, hRequestCompleteEvent;
HINTERNET hInstance, hConnect, hRequest;
char *lpszUrl, *lpszServer;
BOOL bAllDone = FALSE;
void __stdcall Callback(HINTERNET hInternet,
DWORD dwContext,
DWORD dwInternetStatus,
LPVOID lpStatusInfo,
DWORD dwStatusInfoLen);
void main(int argc, char *argv[])
{
if (argc != 4)
{
cout << "Usage: sendreqexasync <server> <url> <size in kilobytes>" << endl;
cout << " Example: sendreqexasync www.foo.com /postfolder/upload.exe 256" << endl;
return;
}
lpszServer = argv[1];
lpszUrl = argv[2];
dwNumKToSend = atoi(argv[3]);
FillMemory(lpOutBuf, 1024, 'A');
hConnectedEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
hRequestCompleteEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
hInstance = InternetOpen("sendreqexasync",
INTERNET_OPEN_TYPE_PRECONFIG,
NULL,
NULL,
INTERNET_FLAG_ASYNC);
if (hInstance == NULL)
{
cout << "InternetOpen failed, error " << GetLastError();
return;
}
if (InternetSetStatusCallback(hInstance,
(INTERNET_STATUS_CALLBACK)&Callback) == INTERNET_INVALID_STATUS_CALLBACK)
{
cout << "InternetSetStatusCallback failed, error " << GetLastError();
return;
}
hConnect = InternetConnect(hInstance,
lpszServer,
INTERNET_DEFAULT_HTTP_PORT,
NULL,
NULL,
INTERNET_SERVICE_HTTP,
0,
1);
if (hConnect == NULL)
{
if (GetLastError() != ERROR_IO_PENDING)
{
cout << "InternetConnect failed, error " << GetLastError();
return;
}
WaitForSingleObject(hConnectedEvent, INFINITE);
}
hRequest = HttpOpenRequest(hConnect,
"POST",
lpszUrl,
NULL,
NULL,
NULL,
INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE,
2);
if (hRequest == NULL)
{
if (GetLastError() != ERROR_IO_PENDING)
{
cout << "HttpOpenRequest failed, error " << GetLastError();
return;
}
WaitForSingleObject(hRequestCompleteEvent, INFINITE);
}
INTERNET_BUFFERS IntBuff;
FillMemory(&IntBuff, sizeof(IntBuff), 0);
IntBuff.dwStructSize= sizeof(IntBuff);
IntBuff.dwBufferTotal = 1024*dwNumKToSend;
IntBuff.lpcszHeader = "Content-Type: text/text\r\n";
IntBuff.dwHeadersLength = lstrlen(IntBuff.lpcszHeader);
if (!HttpSendRequestEx(hRequest,
&IntBuff,
NULL,
0,
2))
{
if (GetLastError() != ERROR_IO_PENDING)
{
cout << "HttpSendRequestEx failed, error " << GetLastError();
return;
}
cout << "HttpSendRequestEx called successfully" << endl;
cout.flush();
WaitForSingleObject(hRequestCompleteEvent, INFINITE);
}
for (dwNumKSent = 0; dwNumKSent < dwNumKToSend; dwNumKSent++)
{
DWORD dwBytesWritten;
if(!InternetWriteFile(hRequest,
lpOutBuf,
1024,
&dwBytesWritten))
{
if (GetLastError() != ERROR_IO_PENDING)
{
cout << "InternetWriteFile failed, error " << GetLastError();
return;
}
else
{
cout << "InternetWriteFile completing asynchronously" << endl;
cout.flush();
WaitForSingleObject(hRequestCompleteEvent, INFINITE);
}
}
}
cout << "Calling HttpEndRequest" << endl;
cout.flush();
if (!HttpEndRequest(hRequest, NULL, HSR_INITIATE, 2))
{
if (GetLastError() == ERROR_IO_PENDING)
{
cout << "HttpEndRequest called" << endl;
cout.flush();
WaitForSingleObject(hRequestCompleteEvent, INFINITE);
}
else
{
cout << "HttpEndRequest failed, error " << GetLastError() << endl;
return;
}
}
cout << "------------------- Read the response -------------------" << endl;
char lpReadBuff[256];
do
{
INTERNET_BUFFERS InetBuff;
FillMemory(&InetBuff, sizeof(InetBuff), 0);
InetBuff.dwStructSize = sizeof(InetBuff);
InetBuff.lpvBuffer = lpReadBuff;
InetBuff.dwBufferLength = sizeof(lpReadBuff) - 1;
cout << "Calling InternetReadFileEx" << endl;
cout.flush();
if (!InternetReadFileEx(hRequest,
&InetBuff,
0, 2))
{
if (GetLastError() == ERROR_IO_PENDING)
{
cout << "Waiting for InternetReadFile to complete" << endl;
cout.flush();
WaitForSingleObject(hRequestCompleteEvent, INFINITE);
}
else
{
cout << "InternetReadFileEx failed, error " << GetLastError();
cout.flush();
return;
}
}
lpReadBuff[InetBuff.dwBufferLength] = 0;
cout << lpReadBuff;
cout.flush();
if (InetBuff.dwBufferLength == 0)
bAllDone = TRUE;
} while (bAllDone == FALSE);
cout << endl << endl << "------------------- Request Complete ----------------" << endl;
}
void __stdcall Callback(HINTERNET hInternet,
DWORD dwContext,
DWORD dwInternetStatus,
LPVOID lpStatusInfo,
DWORD dwStatusInfoLen)
{
cout << "Callback dwInternetStatus: " << dwInternetStatus << " Context: " << dwContext << endl;
cout.flush();
switch(dwContext)
{
case 1: // Connection handle
if (dwInternetStatus == INTERNET_STATUS_HANDLE_CREATED)
{
INTERNET_ASYNC_RESULT *pRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
hConnect = (HINTERNET)pRes->dwResult;
cout << "Connect handle created" << endl;
cout.flush();
SetEvent(hConnectedEvent);
}
break;
case 2: // Request handle
switch(dwInternetStatus)
{
case INTERNET_STATUS_HANDLE_CREATED:
{
INTERNET_ASYNC_RESULT *pRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
hRequest = (HINTERNET)pRes->dwResult;
cout << "Request handle created" << endl;
cout.flush();
}
break;
case INTERNET_STATUS_REQUEST_SENT:
{
DWORD *lpBytesSent = (DWORD*)lpStatusInfo;
cout << "Bytes Sent: " << *lpBytesSent << endl;
dwNumBytesComplete += *lpBytesSent;
}
break;
case INTERNET_STATUS_REQUEST_COMPLETE:
{
INTERNET_ASYNC_RESULT *pAsyncRes = (INTERNET_ASYNC_RESULT *)lpStatusInfo;
cout << "Function call finished" << endl;
cout << "dwResult: " << pAsyncRes->dwResult << endl;
cout << "dwError: " << pAsyncRes->dwError << endl;
cout.flush();
SetEvent(hRequestCompleteEvent);
}
break;
case INTERNET_STATUS_RECEIVING_RESPONSE:
cout << "Receiving Response" << endl;
cout.flush();
break;
case INTERNET_STATUS_RESPONSE_RECEIVED:
{
DWORD *dwBytesReceived = (DWORD*)lpStatusInfo;
cout << "Received " << *dwBytesReceived << endl;
cout.flush();
}
}
}
}
參考的異步類：
1 include <wininet.h>
2 #include <mmsystem.h>
3
4 class AsyncWinINet
5 {
6 public:
7 typedef void (*notify_fp)(const StringMap&);
8
9 class thread_info
10 {
11 public:
12 thread_info(const String& _url, //請求下載的地址(in)
13 const StringMap& _request_headrs, //請求頭request_headrs(in)
14 const notify_fp& _pfp, //下載進度通知回調函數指針
15 const StringMap& _pfp_param,
16 String& _response_headrs, //返回頭response_headrs(out)
17 const String& _saved_filename, //下載內容保存文件名(in)
18 String& _response_content, //返回內容(out)
19 size_t _read_content_size) //控制保存在response_content中內容的長度(in)) :
20 : request_headrs(_request_headrs), pfp(_pfp),
21 pfp_param(_pfp_param), //pfp函數傳回參數
22 response_headrs(_response_headrs), saved_filename(_saved_filename),
23 response_content(_response_content), read_content_size(_read_content_size)
24 {
25 this->response_headrs.clear();
26 this->response_content.clear();
27 this->url = StringUtil::EncodeURIComponent(_url);
28 for(int i = 0; i < 3; ++i)
29 {
30 this->hEvent[i] = CreateEvent(NULL,TRUE,FALSE,NULL);
31 }
32 }
33
34 HANDLE hThread;
35 DWORD dwThreadID;
36 HANDLE hCallbackThread;
37 DWORD dwCallbackThreadID;
38 HANDLE hEvent[3];
39 LPVOID hInternet;
40 LPVOID hFile;
41 DWORD dwStatusCode;
42 DWORD dwContentLength;
43
44 String url; //請求下載的地址(in)
45 const StringMap& request_headrs; //請求頭request_headrs(in)
46 const notify_fp& pfp; //下載進度通知回調函數指針
47 const StringMap& pfp_param; //pfp函數傳回參數
48
49 String& response_headrs; //返回頭response_headrs(out)
50 const String& saved_filename; //下載內容保存文件名(in)
51 String& response_content; //返回內容(out)
52 size_t read_content_size; //控制保存在response_content中內容的長度(in)
53 };
54
55 /*******************************************************************************
56 * 函數：download
57 * 功能：下載，返回WinINet_ERR_CODE值
58 * 說明：關于notify_fp 類型說明: 函數的參數為StringMap類型，傳回的變量名與變量值
59 * 2007-12
60 *******************************************************************************/
61 static DWORD download(const String& url, //請求下載的地址(in)
62 const StringMap& request_headrs, //請求頭request_headrs(in)
63 const notify_fp& pfp, //下載進度通知回調函數指針
64 const StringMap& pfp_param, //pfp函數傳回參數
65 String& response_headrs, //返回頭response_headrs(out)
66 const String& saved_filename, //下載內容保存文件名(in)
67 String& response_content, //返回內容(out)
68 size_t read_content_size = 0); //控制保存在response_content中內容的長度(in)
69
70 protected:
71 static BOOL WaitExitEvent(thread_info *p);
72 static DWORD WINAPI AsyncThread(LPVOID lpParameter);
73 static DWORD WINAPI AsyncCallbackThread(LPVOID lpParameter);
74 static VOID CALLBACK AsyncInternetCallback(HINTERNET hInternet,
75 DWORD dwContext,
76 DWORD dwInternetStatus,
77 LPVOID lpvStatusInformation,
78 DWORD dwStatusInformationLength);
79
80 };
81
1 #include "AsyncWinINet.h"
2
3 #include "stdafx.h"
4
5 #pragma comment(lib, "Winmm.lib")
6 #pragma comment(lib, "Wininet.lib")
7
8 DWORD AsyncWinINet::download(const Fagex::String &url, const Fagex::StringMap &request_headrs,
9 const Fagex::AsyncWinINet::notify_fp &pfp, const Fagex::StringMap &pfp_param, Fagex::String &response_headrs,
10 const Fagex::String &saved_filename, Fagex::String &response_content, size_t read_content_size)
11 {
12 thread_info info(url, request_headrs, pfp,
13 pfp_param, response_headrs, saved_filename,
14 response_content, read_content_size);
15
16 info.hThread = CreateThread(NULL,
17 0,
18 AsyncWinINet::AsyncThread,
19 &info,
20 NULL,
21 &info.dwThreadID);
22
23 WaitForSingleObject(info.hThread, INFINITE); //等待子線程安全退出
24 CloseHandle(info.hThread);//關閉線程句柄
25
26 return TRUE;
27 }
28
29 //---------------------------------------------------------------------
30 DWORD WINAPI AsyncWinINet::AsyncThread(LPVOID lpParameter)
31 {
32 thread_info* p = (thread_info*)lpParameter;
33
34 //a. 使用標記 INTERNET_FLAG_ASYNC 初始化 InternetOpen
35 String user_agent("Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; TencentTraveler ; .NET CLR 2.0.50727)");
36 StringMap iheadrs(p->request_headrs.begin(), p->request_headrs.end());
37 StringMap::iterator it = iheadrs.find("User-Agent");
38 if(it == iheadrs.end()) iheadrs["User-Agent"] = user_agent;
39 else user_agent = it->second;
40
41 p->hInternet = InternetOpen(user_agent.c_str(),
42 INTERNET_OPEN_TYPE_PRECONFIG,
43 NULL,
44 NULL,
45 INTERNET_FLAG_ASYNC);
46
47 //ResetEvent(p->hEvent[0]);
48 //p->hCallbackThread = CreateThread(NULL,
49 // 0,
50 // AsyncWinINet::AsyncCallbackThread,
51 // p,
52 // NULL,
53 // &p->dwCallbackThreadID);
54 //WaitForSingleObject(p->hEvent[0], INFINITE);//等待回調函數設置成功事件
55 InternetSetStatusCallback(p->hInternet, AsyncWinINet::AsyncInternetCallback);
56
57 String sheadrs;
58 for(it = iheadrs.begin(); it != iheadrs.end(); ++it)
59 {
60 sheadrs += it->first + ":" + it->second;
61 if(it->second.find(StringUtil::enter) == String::npos) { sheadrs += StringUtil::enter; }
62 }
63 sheadrs += StringUtil::enter;
64
65 DWORD start_time = timeGetTime();
66 ResetEvent(p->hEvent[0]); //重置句柄被創建事件
67 p->hFile = InternetOpenUrl(p->hInternet, p->url.c_str(), sheadrs.c_str(), sheadrs.length(),
68 INTERNET_FLAG_DONT_CACHE | INTERNET_FLAG_RELOAD, (DWORD)p);
69
70 FILE *fp = fopen(p->saved_filename.c_str(), "w+");
71 while(true)
72 {
73 if (NULL == p->hFile)
74 {
75 DWORD dwError = ::GetLastError();
76 if (ERROR_IO_PENDING == dwError || ERROR_SUCCESS == dwError)
77 {
78 if (WaitExitEvent(p)) { break; }
79 }
80 else break;
81 }
82
83 //讀取返回文件頭
84 DWORD dwLength = 0;
85 LPVOID lpOutBuffer = NULL;
86 while(true) //讀取response_headrs數據
87 {
88 if(!HttpQueryInfo(p->hFile, HTTP_QUERY_RAW_HEADERS_CRLF,
89 lpOutBuffer, &dwLength, NULL))
90 {
91 DWORD err_code = GetLastError();
92 if (err_code == ERROR_HTTP_HEADER_NOT_FOUND) break;
93 else if(err_code == ERROR_INSUFFICIENT_BUFFER)
94 {
95 lpOutBuffer = new char[dwLength];
96 continue;
97 }
98 else break;
99 }
100 break;
101 }
102 if(lpOutBuffer != NULL)
103 {
104 p->response_headrs.append((char*)lpOutBuffer,dwLength);
105 delete [] lpOutBuffer;
106 }
107
108 //e. 使用 HttpQueryInfo 分析頭信息 HttpQueryInfo 使用非阻塞方式，所以不用等待
109 DWORD dwStatusSize = sizeof(p->dwStatusCode);
110 if (FALSE == HttpQueryInfo(p->hFile, //獲取返回狀態碼
111 HTTP_QUERY_STATUS_CODE | HTTP_QUERY_FLAG_NUMBER,
112 &p->dwStatusCode, &dwStatusSize, NULL)) { break; }
113
114 //判斷狀態碼是不是 200
115 if (HTTP_STATUS_OK != p->dwStatusCode) break;
116
117 StringMap msgMap(p->pfp_param.begin(), p->pfp_param.end());
118 msgMap["url"] = p->url;
119
120 //獲取返回的Content-Length
121 //DWORD dwLengthSize = sizeof(p->dwContentLength);
122 //if (FALSE == HttpQueryInfo(p->hFile,
123 //HTTP_QUERY_CONTENT_LENGTH | HTTP_QUERY_FLAG_NUMBER,
124 //&p->dwContentLength, &dwLengthSize, NULL)) { p->dwContentLength = 0; }
125
126 //f. 使用標記 IRF_ASYNC 讀數據 InternetReadFileEx
127 //為了向主線程報告進度，我們設置每次讀數據最多 1024 字節
128
129 char lpvBuffer[1024];
130 p->dwContentLength = 0; //Content-Length: 202749
131 while(true)
132 {
133 INTERNET_BUFFERS i_buf = {0};
134 i_buf.dwStructSize = sizeof(INTERNET_BUFFERS);
135 i_buf.lpvBuffer = lpvBuffer;
136 i_buf.dwBufferLength = 1024;
137
138 //重置讀數據事件
139 ResetEvent(p->hEvent[0]);
140 if (FALSE == InternetReadFileEx(p->hFile, &i_buf, IRF_ASYNC, (DWORD)p))
141 {
142 if (ERROR_IO_PENDING == ::GetLastError())
143 {
144 if (WaitExitEvent(p)) break;
145 }
146 else break;
147 }
148 else
149 {
150 //在網絡傳輸速度快，步長較小的情況下，InternetReadFileEx 經常會直接返回成功，
151 //因此要判斷是否發生了用戶要求終止子線程事件。
152 if (WAIT_OBJECT_0 == WaitForSingleObject(p->hEvent[2], 0))
153 {
154 ResetEvent(p->hEvent[2]);
155 break;
156 }
157 }
158
159 if(i_buf.dwBufferLength == 0)
160 {
161 DWORD time = timeGetTime() - start_time;
162 if(time != 0)
163 {
164 Real speed = (Real)p->dwContentLength;
165 speed /= ((Real)time)/1000.0f;
166 speed /= 1024.0f;
167 msgMap["speed"] = StringUtil::toString((DWORD)speed);
168 }
169 if(p->pfp) p->pfp(msgMap);
170 break;
171 }
172 if(fp)
173 {
174 fwrite(i_buf.lpvBuffer, sizeof(char), i_buf.dwBufferLength, fp);
175 }
176 if(p->read_content_size > p->response_content.size())
177 {
178 p->response_content.append((char*)i_buf.lpvBuffer, i_buf.dwBufferLength);
179 }
180 p->dwContentLength += i_buf.dwBufferLength;
181 }
182 break;
183 }
184
185 if(fp)
186 {
187 fflush(fp); fclose(fp); fp = NULL;
188 }
189
190 if(p->hFile)
191 {
192 InternetCloseHandle(p->hFile);//關閉 m_hFile
193 while (!WaitExitEvent(p)) //等待句柄被關閉事件或者要求子線程退出事件
194 {
195 ResetEvent(p->hEvent[0]);
196 }
197 }
198
199 //設置子線程退出事件，通知回調線程退出
200 SetEvent(p->hEvent[2]);
201
202 //等待回調線程安全退出
203 //WaitForSingleObject(p->hCallbackThread, INFINITE);
204 //CloseHandle(p->hCallbackThread);
205
206 //注銷回調函數
207 InternetSetStatusCallback(p->hInternet, NULL);
208 InternetCloseHandle(p->hInternet);
209
210 return TRUE;
211 }
212
213 //------------------------------------------------------------------------------------
214 DWORD WINAPI AsyncWinINet::AsyncCallbackThread(LPVOID lpParameter)
215 {
216 thread_info *p = (thread_info*)lpParameter;
217 InternetSetStatusCallback(p->hInternet, AsyncWinINet::AsyncInternetCallback);
218
219 //通知子線程回調函數設置成功，子線程可以繼續工作
220 SetEvent(p->hEvent[0]);
221
222 //等待用戶終止事件或者子線程結束事件
223 //子線程結束前需要設置子線程結束事件，并等待回調線程結束
224 WaitForSingleObject(p->hEvent[2], INFINITE);
225
226 return 0;
227 }
228
229 //----------------------------------------------------------------------------
230 VOID CALLBACK AsyncWinINet::AsyncInternetCallback(HINTERNET hInternet,
231 DWORD dwContext,
232 DWORD dwInternetStatus,
233 LPVOID lpvStatusInformation,
234 DWORD dwStatusInformationLength)
235 {
236 thread_info* p = (thread_info*)dwContext;
237
238 //在我們的應用中，我們只關心下面三個狀態
239 switch(dwInternetStatus)
240 {
241 //句柄被創建
242 case INTERNET_STATUS_HANDLE_CREATED:
243 p->hFile = (HINTERNET)(((LPINTERNET_ASYNC_RESULT)
244 (lpvStatusInformation))->dwResult);
245 break;
246
247 //句柄被關閉
248 case INTERNET_STATUS_HANDLE_CLOSING:
249 SetEvent(p->hEvent[1]);
250 break;
251
252 //一個請求完成，比如一次句柄創建的請求，或者一次讀數據的請求
253 case INTERNET_STATUS_REQUEST_COMPLETE:
254 if (ERROR_SUCCESS == ((LPINTERNET_ASYNC_RESULT)
255 (lpvStatusInformation))->dwError)
256 {
257 //設置句柄被創建事件或者讀數據成功完成事件
258 SetEvent(p->hEvent[0]);
259 }
260 else
261 {
262 //如果發生錯誤，則設置子線程退出事件 這里也是一個陷阱，經常會忽視處理這個錯誤，
263 SetEvent(p->hEvent[2]);
264 }
265 break;
266
267 case INTERNET_STATUS_CONNECTION_CLOSED:
268 SetEvent(p->hEvent[2]);
269 break;
270
271 }
272 }
273
274 //--------------------------------------------------------------------
275 BOOL AsyncWinINet::WaitExitEvent(thread_info *p)
276 {
277 DWORD dwRet = WaitForMultipleObjects(3, p->hEvent, FALSE, INFINITE);
278
279 switch (dwRet)
280 {
281 case WAIT_OBJECT_0://句柄被創建事件或者讀數據請求成功完成事件
282 case WAIT_OBJECT_0+1://句柄被關閉事件
283 case WAIT_OBJECT_0+2://用戶要求終止子線程事件或者發生錯誤事件
284 break;
285 }
286 return WAIT_OBJECT_0 != dwRet;
287 }
288