HOWTO: Simple Internet API Sample -- HTML Into Memo Field

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a on the following platforms: NT, Win95

SUMMARY

The sample program below will connect to an Internet or intranet Web page and bring back the HTML code and store it into a memo field of a FoxPro table.

MORE INFORMATION

Save the sample program below into a Visual FoxPro program file. Use the following syntax to run the program:

   DO readurl.prg WITH "http://www.microsoft.com"

Note that Microsoft Internet Explorer must be installed on the computer.

   * READURL.PRG - return the HTML for a specified URL in HURL.MEMO
   *
   * passed: URLName, in the form "http://www.microsoft.com"
   *
   * returns: length of HTML file
   *
   * usage:
   *
   *      m.urllength = readurl("http://www.microsoft.com")
   *
   *
   * notes:
   * 1 - IE does not need to be running to use this, but must be installed,
   * as the program uses an option that gets information from the registry
   *
   * 2 - the URL name apparently MUST be passed in the form shown above.
   *

   PARAMETERS UrlName

   DECLARE INTEGER InternetOpen IN wininet.DLL STRING sAgent, ;
         INTEGER lAccessType, STRING sProxyName, ;
         STRING sProxyBypass, INTEGER lFlags

   DECLARE INTEGER InternetOpenUrl IN wininet.DLL ;
      INTEGER hInternetSession, STRING sUrl, STRING sHeaders, ;
      INTEGER lHeadersLength, INTEGER lFlags, INTEGER lContext

   DECLARE INTEGER InternetReadFile IN wininet.DLL INTEGER hfile, ;
         STRING @sBuffer, INTEGER lNumberofBytesToRead, INTEGER @lBytesRead

   DECLARE short InternetCloseHandle IN wininet.DLL INTEGER hInst

   #DEFINE INTERNET_OPEN_TYPE_PRECONFIG 0
   #DEFINE INTERNET_OPEN_TYPE_DIRECT 1
   #DEFINE INTERNET_OPEN_TYPE_PROXY 3
   #DEFINE SYNCHRONOUS 0
   #DEFINE INTERNET_FLAG_RELOAD 2147483648
   #DEFINE CR CHR(13)


   IF NOT FILE("hurl.dbf")
         CREATE TABLE hurl (MEMO M)
   ELSE
         USE hurl
   ENDIF
   APPEND BLANK

   * what application is using Internet services?
   sAgent = "VPF 5.0"

   hInternetSession = InternetOpen(sAgent, INTERNET_OPEN_TYPE_PRECONFIG, ;
         '', '', SYNCHRONOUS)

   * debugging line - uncomment to see session handle
   * WAIT WINDOW "Internet session handle: " + LTRIM(STR(hInternetSession))

   IF hInternetSession = 0
         WAIT WINDOW "Internet session cannot be established" TIME 2
         RETURN 0
   ENDIF

   hUrlFile = InternetOpenUrl(hInternetSession, UrlName, '', ;
         0, INTERNET_FLAG_RELOAD, 0)

   * debugging line - uncomment to see URL handle
   * WAIT WINDOW "URL Handle: " + LTRIM(STR(hUrlFile))

   IF hUrlFile = 0
         WAIT WINDOW "URL cannot be opened"
         RETURN 0
   ENDIF

   DO WHILE .T.
         * set aside a big buffer
         sReadBuffer = SPACE(32767)
         lBytesRead = 0
         m.OK = InternetReadFile(hUrlFile, @sReadBuffer, ;
            LEN(sReadBuffer), @lBytesRead)

         * debugging code - uncomment if necessary
         *WAIT WINDOW "hURLFile: " + LTRIM(STR(hURLFile)) + CR + ;
         *                  "lBytesRead: " + LTRIM(STR(lBytesRead)) + CR ;
         *                  + "m.OK      : " + LTRIM(STR(m.OK))

         REPLACE hurl.MEMO WITH sReadBuffer ADDITIVE

         * uncomment to watch the changes to the memo file
         * MODIFY MEMO hurl.memo

         * error trap - either a read failure or read past eof()
         IF m.OK = 0 OR lBytesRead = 0
            EXIT
         ENDIF
   ENDDO

   * close all the handles we opened
   =InternetCloseHandle(hUrlFile)
   =InternetCloseHandle(hInternetSession)

   * return the number of bytes read
   RETURN LEN(hurl.memo)

REFERENCES

"Visual Basic and the Win32 Internet SDK" by James Braun (September 1996 MSDN)

Keywords          : FxotherSample FxprgGeneral vfoxwin
Technology        : kbInetDev
Version           : Win:3.0,3.0b,5.0,5.0a
Platform          : WINDOWS
Issue type        : kbhowto