Reading from a JAR file

[Lee Feder]

Is it possible to load data from a file held in one of the jar files in the ARCHIVE parameter?
Basically, I've got a couple of property files that I'd love the applet to read when it gets initialised.
Can anyone help?

[Lee Feder]

Oh I forgot, the applet must be able to run offline too.

[Nathan Pruett]

Lee,
Here is how you would do it :

URL url = ClassName.class.getResource( "image.gif" ); 
Image image = Toolkit.getDefaultToolkit().getImage( url );

Where you would replace ClassName with the real name of your class, and image.gif with the real name of the image you are loading ( along with it's path in the JAR file if applicable ). This will work both on and offline.
HTH,
-Nate

[Lee Feder]

Thanks Nate, it works a treat.

[Khurram Fakhar]

Hi , ppl
It is working fine in IE but it is giving error with NS..
Kindly help me out
Regards
Khurram Fakhar

[Nathan Pruett]

Okay... Ummm... could you say what error it is giving in Netscape...

[Khurram Fakhar]

It works fine with
URL url1 = ClassName.class.getResource("loginpage_image.jpg");
but on the second line it gives the following error:
line :
panelImage=Toolkit.getDefaultToolkit().getImage(url1);
error :
java.lang.NullPointerException
at sun.awt.SunToolkit.getImageFromHash(Compiled Code)
at sun.awt.SunToolkit.getImage(Compiled Code)
at ClientMain.images(Compiled Code)
at ClientMain.init(Compiled Code)
* at netscape.applet.DerivedAppletFrame$InitAppletEvent.dispatch(Compiled Code)
at java.awt.EventDispatchThread$EventPump.dispatchEvents(Compiled Code)
at java.awt.EventDispatchThread.run(Compiled Code)
at netscape.applet.DerivedAppletFrame$AppletEventDispatchThread.run(Compiled Code)

but working fine with IE .. ..
isn't it strange ?

regards
Khurram Fakhar

[Nathan Pruett]

Hmmm... I don't have Netscape here at work to test it out on, but have you tried to replace :

Image image = Toolkit.getDefaultToolkit().getImage( url );

with :

Image image = getImage( url );

( I assume you are doing this in an Applet... )

Hopefully this works... if not please post again...


-Nate

[Nathan Pruett]

Actually, ignore the previous post... I did a search on this and found that Netscape's getResource() method is broken...

Here's some code I found in a JavaWorld article ( http://www.javaworld.com/javaworld/jw-07-1998/jw-07-jar_p.html ) that should help you out...

 protected Image getImageFromJAR(String fileName){
    if( fileName == null ) return null;
 
    Image image = null;
    byte[] thanksToNetscape = null;
    Toolkit toolkit = Toolkit.getDefaultToolkit();
    InputStream in = getClass().getResourceAsStream(fileName);
 
    try{
       int length = in.available();
       thanksToNetscape = new byte[length];
       in.read( thanksToNetscape );
       image = toolkit.createImage( thanksToNetscape );
    }
    catch(Exception exc){
       System.out.println( exc +" getting resource " +fileName );
       return null;
    }
    return image;
 }

You should call it in your code like this:

// Assuming your images directory exists in a subdirectory of 
// the package path, you could call the method above to retrieve 
// an image, using the following line of code: 
 
Image image = getImageFromJAR( "images/myImage.gif");

HTH,
-Nate

[Khurram Fakhar]

Hay Thanx a million Man
It worked. I studied the whole article .. very well written article .
Thanx once again ..
Regards
Khurram Fakhar