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Applets Cookies Password

Posted on 2000-03-21
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Last Modified: 2013-11-23
I have a site which is to be viewed locally with a number of applets on.  I want some of the applets to check if the user has logged in, and if not, ask them their password.  This would then be stored in the browser for that session only, so if they went to pages with other applets on, those applets would know the user was logged in and not need to ask.

I guess the best way to do this is cookies - but I don't know how to write these with Java, or even if you can.  I would prefer a Java-only solution, but some Java/HTML/JavaScript-based solution would be OK too.

Cheers,

Tom
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Question by:yatest5
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Expert Comment

by:muraliram
Comment Utility
Dear yatest5,

    If you are using Java Servlets then you can do this easily using Servlet Session API. Otherwise you can do this from JavaScript. I prefer Java Servlets

Also visit

http://www.cookiecentral.com/faq/index.shtml

Bye

All the best

Murali
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by:yatest5
Comment Utility
Cheers Murali, but unfortunately I'm not using servlets.  I'll have a look at your link though.

Ta,

Tom
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Expert Comment

by:dmaguillo
Comment Utility
Hi yatest5. Here i have an useful page with cookies examples that can help you...

http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/index.html

(It`s based on servlets)

Bye... :)
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Expert Comment

by:muraliram
Comment Utility
Dear yatest5,

      Teh link I have given is not related with Servlet. Go and have a llok at it. It may help you. Try it in
your own.

Bye

Murali
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by:yatest5
Comment Utility
Adjusted points from 100 to 150
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Expert Comment

by:heyhey_
Comment Utility
as far as I remember, applets can't access cookies (after all, cookies are kind of client side 'resources') - you'll need some JavaScript + Java soluton.
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by:yatest5
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So the first person to show me how to call javascript cookie-writing code from an applet gets the cookies, erm, points.
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Author Comment

by:yatest5
Comment Utility
mmmmmmmmmmmmmm, I like cookies, yummeee
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by:muraliram
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Dear yatest5,

Try the following. Its a link which I have given you earlly. I think you haven't had a llok into it. Try the following


<html>
<head>
<title>Cookie Functions</title>
</head>
<body>
<script language="javascript">
<!-- begin script
//
//  Cookie Functions -- "Night of the Living Cookie" Version (25-Jul-96)
//
//  Written by:  Bill Dortch, hIdaho Design <bdortch@hidaho.com>
//  The following functions are released to the public domain.
//
//  This version takes a more aggressive approach to deleting
//  cookies.  Previous versions set the expiration date to one
//  millisecond prior to the current time; however, this method
//  did not work in Netscape 2.02 (though it does in earlier and
//  later versions), resulting in "zombie" cookies that would not
//  die.  DeleteCookie now sets the expiration date to the earliest
//  usable date (one second into 1970), and sets the cookie's value
//  to null for good measure.
//
//  Also, this version adds optional path and domain parameters to
//  the DeleteCookie function.  If you specify a path and/or domain
//  when creating (setting) a cookie**, you must specify the same
//  path/domain when deleting it, or deletion will not occur.
//
//  The FixCookieDate function must now be called explicitly to
//  correct for the 2.x Mac date bug.  This function should be
//  called *once* after a Date object is created and before it
//  is passed (as an expiration date) to SetCookie.  Because the
//  Mac date bug affects all dates, not just those passed to
//  SetCookie, you might want to make it a habit to call
//  FixCookieDate any time you create a new Date object:
//
//    var theDate = new Date();
//    FixCookieDate (theDate);
//
//  Calling FixCookieDate has no effect on platforms other than
//  the Mac, so there is no need to determine the user's platform
//  prior to calling it.
//
//  This version also incorporates several minor coding improvements.
//
//  **Note that it is possible to set multiple cookies with the same
//  name but different (nested) paths.  For example:
//
//    SetCookie ("color","red",null,"/outer");
//    SetCookie ("color","blue",null,"/outer/inner");
//
//  However, GetCookie cannot distinguish between these and will return
//  the first cookie that matches a given name.  It is therefore
//  recommended that you *not* use the same name for cookies with
//  different paths.  (Bear in mind that there is *always* a path
//  associated with a cookie; if you don't explicitly specify one,
//  the path of the setting document is used.)
//  
//  Revision History:
//
//    "Toss Your Cookies" Version (22-Mar-96)
//      - Added FixCookieDate() function to correct for Mac date bug
//
//    "Second Helping" Version (21-Jan-96)
//      - Added path, domain and secure parameters to SetCookie
//      - Replaced home-rolled encode/decode functions with Netscape's
//        new (then) escape and unescape functions
//
//    "Free Cookies" Version (December 95)
//
//
//  For information on the significance of cookie parameters, and
//  and on cookies in general, please refer to the official cookie
//  spec, at:
//
//      http://www.netscape.com/newsref/std/cookie_spec.html    
//
//******************************************************************
//
// "Internal" function to return the decoded value of a cookie
//
function getCookieVal (offset) {
  var endstr = document.cookie.indexOf (";", offset);
  if (endstr == -1)
    endstr = document.cookie.length;
  return unescape(document.cookie.substring(offset, endstr));
}
//
//  Function to correct for 2.x Mac date bug.  Call this function to
//  fix a date object prior to passing it to SetCookie.
//  IMPORTANT:  This function should only be called *once* for
//  any given date object!  See example at the end of this document.
//
function FixCookieDate (date) {
  var base = new Date(0);
  var skew = base.getTime(); // dawn of (Unix) time - should be 0
  if (skew > 0)  // Except on the Mac - ahead of its time
    date.setTime (date.getTime() - skew);
}
//
//  Function to return the value of the cookie specified by "name".
//    name - String object containing the cookie name.
//    returns - String object containing the cookie value, or null if
//      the cookie does not exist.
//
function GetCookie (name) {
  var arg = name + "=";
  var alen = arg.length;
  var clen = document.cookie.length;
  var i = 0;
  while (i < clen) {
    var j = i + alen;
    if (document.cookie.substring(i, j) == arg)
      return getCookieVal (j);
    i = document.cookie.indexOf(" ", i) + 1;
    if (i == 0) break;
  }
  return null;
}
//
//  Function to create or update a cookie.
//    name - String object containing the cookie name.
//    value - String object containing the cookie value.  May contain
//      any valid string characters.
//    [expires] - Date object containing the expiration data of the cookie.  If
//      omitted or null, expires the cookie at the end of the current session.
//    [path] - String object indicating the path for which the cookie is valid.
//      If omitted or null, uses the path of the calling document.
//    [domain] - String object indicating the domain for which the cookie is
//      valid.  If omitted or null, uses the domain of the calling document.
//    [secure] - Boolean (true/false) value indicating whether cookie transmission
//      requires a secure channel (HTTPS).  
//
//  The first two parameters are required.  The others, if supplied, must
//  be passed in the order listed above.  To omit an unused optional field,
//  use null as a place holder.  For example, to call SetCookie using name,
//  value and path, you would code:
//
//      SetCookie ("myCookieName", "myCookieValue", null, "/");
//
//  Note that trailing omitted parameters do not require a placeholder.
//
//  To set a secure cookie for path "/myPath", that expires after the
//  current session, you might code:
//
//      SetCookie (myCookieVar, cookieValueVar, null, "/myPath", null, true);
//
function SetCookie (name,value,expires,path,domain,secure) {
  document.cookie = name + "=" + escape (value) +
    ((expires) ? "; expires=" + expires.toGMTString() : "") +
    ((path) ? "; path=" + path : "") +
    ((domain) ? "; domain=" + domain : "") +
    ((secure) ? "; secure" : "");
}

//  Function to delete a cookie. (Sets expiration date to start of epoch)
//    name -   String object containing the cookie name
//    path -   String object containing the path of the cookie to delete.  This MUST
//             be the same as the path used to create the cookie, or null/omitted if
//             no path was specified when creating the cookie.
//    domain - String object containing the domain of the cookie to delete.  This MUST
//             be the same as the domain used to create the cookie, or null/omitted if
//             no domain was specified when creating the cookie.
//
function DeleteCookie (name,path,domain) {
  if (GetCookie(name)) {
    document.cookie = name + "=" +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }
}

//
//  Examples
//
var expdate = new Date ();
FixCookieDate (expdate); // Correct for Mac date bug - call only once for given Date object!
expdate.setTime (expdate.getTime() + (24 * 60 * 60 * 1000)); // 24 hrs from now
SetCookie ("ccpath", "http://www.hidaho.com/colorcenter/", expdate);
SetCookie ("ccname", "hIdaho Design ColorCenter", expdate);
SetCookie ("tempvar", "This is a temporary cookie.");
SetCookie ("ubiquitous", "This cookie will work anywhere in this domain",null,"/");
SetCookie ("paranoid", "This cookie requires secure communications",expdate,"/",null,true);
SetCookie ("goner", "This cookie must die!");
document.write (document.cookie + "<br>");
DeleteCookie ("goner");
document.write (document.cookie + "<br>");
document.write ("ccpath = " + GetCookie("ccpath") + "<br>");
document.write ("ccname = " + GetCookie("ccname") + "<br>");
document.write ("tempvar = " + GetCookie("tempvar") + "<br>");
// end script -->
</script>
</body>
</html>


This is lengthy. But teh code contains some utility functions whch will be useful.

Bye

Murali
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Author Comment

by:yatest5
Comment Utility
Cheers Murali,

This is all good stuff but I still don't know how to call jscript functions and access variables from a java applet.

ta
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Accepted Solution

by:
kollegov earned 150 total points
Comment Utility
You would need to download LiveConnect package from
http://developer.netscape.com MIE4+ and NN3 both have this package
in browsers' standard so you don't need to bundle it with applet.
But you would need it to compile applet in JDK.

Note also that MIE cookie is only for http:// content.
You can't store cookie when loaded from file://  

Here is solution I used:


import java.awt.*;
import java.applet.*;
import java.net.*;
import netscape.javascript.*;

public class test extends Applet {

  public void init(){

// actually you can evaluate any // command returning String    System.out.println(evaluatejs("document.cookie+''"));
  }

  String evaluatejs(String cmd)
  {try
     {JSObject w=JSObject.getWindow(this);
      String args[] = new String[0];
      w.eval("function vmax_effects_handler(){"+cmd+";};");
      Object o=w.call("vmax_effects_handler",args);
      if(o instanceof String) return (String)o;
     }
    catch(NoClassDefFoundError nf){}  
    catch(UnsatisfiedLinkError le){}
    catch(Exception ex){System.out.println(ex);}
    return null;
  }

}
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Expert Comment

by:muraliram
Comment Utility
Dear yatesty5,

I will tell you how to call applet methods and variables from JavaScript

<html>
<head>
<applet code="your.class" name="myapplet">
</applet>
<script>
var name="myname";
function t()
{
 document.myapplet.somepublicmethod(name);
}
</script>
</head>
</html>

You cann call any public method of the applet and access all the public variables from Javascript and pass any variables.

Bye

Murali
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