使用HttpSendRequestEx后,如需使用HttpQueryInfo,需先用HttpEndRequest结束Request


 


 

HttpQueryInfo

Retrieves header information associated with an HTTP request.

BOOL HttpQueryInfo( HINTERNET hRequest, DWORD dwInfoLevel, LPVOID lpvBuffer, LPDWORDlpdwBufferLength, LPDWORD lpdwIndex );
 

Parameters

hRequest
[in] Handle returned by HttpOpenRequest or InternetOpenUrl.
dwInfoLevel
[in] Combination of an attribute to be retrieved and flags that modify the request. For a list of possible attribute and modifier values, see Query Info Flags.
lpvBuffer
[in, out] Pointer to a buffer to receive the requested information. This parameter must not be NULL.
lpdwBufferLength
[in, out] Pointer to a variable that contains, on entry, the size in bytes of the buffer pointed to by lpvBuffer.

When the function returns successfully, this variable contains the number of bytes of information written to the buffer. In the case of a string, the byte count does not include the string's terminating null character.

When the function fails with an extended error code of ERROR_INSUFFICIENT_BUFFER, the variable pointed to by lpdwBufferLength contains on exit the size, in bytes, of a buffer large enough to receive the requested information. The calling application can then allocate a buffer of this size or larger, and call the function again.

lpdwIndex
[in, out] Pointer to a zero-based header index used to enumerate multiple headers with the same name. When calling the function, this parameter is the index of the specified header to return. When the function returns, this parameter is the index of the next header. If the next index cannot be found, ERROR_HTTP_HEADER_NOT_FOUND is returned.

Return Value

Returns TRUE if successful, or FALSE otherwise. To get extended error information, callGetLastError.

Remarks

You can retrieve the following types of data from HttpQueryInfo:

 

  • Strings (default)
  • SYSTEMTIME (for dates)
  • DWORD (for STATUS_CODE, CONTENT_LENGTH, and so on, if HTTP_QUERY_FLAG_NUMBER has been used)

 

If your application requires that the data be returned as a data type other than a string, you must include the appropriate modifier with the attribute passed to dwInfoLevel.

HttpQueryInfo is available in Microsoft Internet Explorer 3.0 for the ANSI character set and in Internet Explorer 4.0 or later for ANSI and Unicode characters.

Example Code

This example demonstrates a call to HttpQueryInfo.