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http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dnarwebtool/html/msdn_inet.asp
MSDN schrieb:
Let's say that we want to get the size of the HTML page before downloading it so that we can allocate a buffer in the exact size. HttpQueryInfo will get the size of the Web page.
A word of caution: Not all Web pages support getting the page size. (For example, www.toystory.com and www.movielink.com don't support this functionality.) Also, TCP/IP can send less data than requested. Therefore, your application should handle both of these cases and loop around InternetReadFile until the result is True and *lpdwNumberOfBytesRead is 0.
The code to open the file http://www.microsoft.com/msdn/msdninfo/ using HttpOpenRequest, HttpSendRequest, and HttpQueryInfo is shown below. The error checking has been removed.
// Open Internet session.
HINTERNET hSession = ::InternetOpen("MSDN SurfBear",
PRE_CONFIG_INTERNET_ACCESS,
NULL,
INTERNET_INVALID_PORT_NUMBER,
0) ;
// Connect to www.microsoft.com.
HINTERNET hConnect = ::InternetConnect(hSession,
"www.microsoft.com",
INTERNET_INVALID_PORT_NUMBER,
"",
"",
INTERNET_SERVICE_HTTP,
0,
0) ;
// Request the file /MSDN/MSDNINFO/ from the server.
HINTERNET hHttpFile = ::HttpOpenRequest(hConnect,
"GET",
"/MSDN/MSDNINFO/",
HTTP_VERSION,
NULL,
0,
INTERNET_FLAG_DONT_CACHE,
0) ;
// Send the request.
BOOL bSendRequest = ::HttpSendRequest(hHttpFile, NULL, 0, 0, 0);
// Get the length of the file.
char bufQuery[32] ;
DWORD dwLengthBufQuery = sizeof(bufQuery);
BOOL bQuery = ::HttpQueryInfo(hHttpFile,
HTTP_QUERY_CONTENT_LENGTH,
bufQuery,
&dwLengthBufQuery) ;
// Convert length from ASCII string to a DWORD.
DWORD dwFileSize = (DWORD)atol(bufQuery) ;
// Allocate a buffer for the file.
char* buffer = new char[dwFileSize+1] ;
// Read the file into the buffer.
DWORD dwBytesRead ;
BOOL bRead = ::InternetReadFile(hHttpFile,
buffer,
dwFileSize+1,
&dwBytesRead);
// Put a zero on the end of the buffer.
buffer[dwBytesRead] = 0 ;
// Close all of the Internet handles.
::InternetCloseHandle(hHttpFile);
::InternetCloseHandle(hConnect) ;
::InternetCloseHandle(hSession) ;
// Display the file in an edit control.
pEditCtrl->SetWindowText(buffer) ;
