VB and VBA Users Source Code: Read an internet web page with API calls
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VB/VBA Source Code
Read an internet web page with API calls
By:
Andrew Baker
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Date:
Monday, November 27, 2000
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1434
Category:
Internet/Remote Comms
Article:
The following routine uses API calls to read/download an internet file. A routine demonstrating how to use this code can be found at the bottom of this post. Option Explicit Private Declare Function InternetOpen Lib "wininet" Alias "InternetOpenA" (ByVal sAgent As String, ByVal lAccessType As Long, ByVal sProxyName As String, ByVal sProxyBypass As String, ByVal lFlags As Long) As Long Private Declare Function InternetCloseHandle Lib "wininet" (ByVal hInet As Long) As Integer Private Declare Function InternetReadFile Lib "wininet" (ByVal hFile As Long, ByVal sBuffer As String, ByVal lNumBytesToRead As Long, lNumberOfBytesRead As Long) As Integer Private Declare Function InternetOpenUrl Lib "wininet" Alias "InternetOpenUrlA" (ByVal hInternetSession As Long, ByVal lpszUrl As String, ByVal lpszHeaders As String, ByVal dwHeadersLength As Long, ByVal dwFlags As Long, ByVal dwContext As Long) As Long 'Purpose : Retreview text from a web site 'Inputs : sURL The URL and file name to extract the text from ' [lBufferSize] The number of characters to extract. ' If value is -1 the reads the whole page. 'Outputs : The text found on the web site 'Author : Andrew Baker 'Date : 21/10/2000 12:37 'Notes : NOT SUITABLE FOR ACCESSING THE INTERNET THROUGH A PROXY SERVER 'Revisions : Function InternetGetText(sURL As String, Optional lBufferSize As Long = -1) As String Dim lhOpen As Long, lhFile As Long, sBuffer As String, lRet As Long Const clBufferIncrement As Long = 2000 Const scUserAgent = "VBUsers" Const INTERNET_OPEN_TYPE_PRECONFIG = 0, INTERNET_FLAG_EXISTING_CONNECT = &H20000000 Const INTERNET_OPEN_TYPE_DIRECT = 1, INTERNET_OPEN_TYPE_PROXY = 3 Const INTERNET_FLAG_RELOAD = &H80000000 If lBufferSize = -1 Then 'Create an arbitary buffer to read the whole file in parts sBuffer = String$(clBufferIncrement, Chr$(0)) Else 'Create a specified buffer size sBuffer = String$(lBufferSize, Chr$(0)) End If 'Create an internet connection lhOpen = InternetOpen(scUserAgent, INTERNET_OPEN_TYPE_DIRECT, vbNullString, vbNullString, 0) 'Open the url lhFile = InternetOpenUrl(lhOpen, sURL, vbNullString, ByVal 0&, INTERNET_FLAG_RELOAD, ByVal 0&) If lhFile = 0 Then 'Try using proxy InternetCloseHandle lhFile InternetCloseHandle lhOpen 'Create an internet connection lhOpen = InternetOpen(scUserAgent, INTERNET_OPEN_TYPE_PRECONFIG, vbNullString, vbNullString, 0) 'Open the url lhFile = InternetOpenUrl(lhOpen, sURL, vbNullString, ByVal 0&, INTERNET_FLAG_EXISTING_CONNECT, ByVal 0&) End If If lBufferSize = -1 And lhFile <> 0 Then 'Read the whole page Do InternetReadFile lhFile, sBuffer, clBufferIncrement, lRet InternetGetText = InternetGetText & Left$(sBuffer, lRet) Loop While lRet = clBufferIncrement Else 'Read the specified number of bytes from the file InternetReadFile lhFile, sBuffer, lBufferSize, lRet InternetGetText = InternetGetText & Left$(sBuffer, lRet) End If 'clean up InternetCloseHandle lhFile InternetCloseHandle lhOpen End Function 'Demonstration routine '(Note the Debug window will only show the last 255 lines) Sub Test() Dim sInterPage As String sInterPage = InternetGetText("http://www.vbusers.com/home.asp") Debug.Print sInterPage End Sub
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