Re: problem: security using IDE's appletviewer

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.help
Date:
Wed, 07 May 2008 09:26:35 -0700
Message-ID:
<4821a0bd$0$1572$b9f67a60@news.newsdemon.com>
bH wrote:

On May 7, 1:41 am, Knute Johnson <nos...@rabbitbrush.frazmtn.com>
wrote:

bH wrote:

Hi Knute,
You wrote "If you jar up your Applet, access the
image file with; getImage(getClass().getResource
("fname.jpg"));
The applet is correctly jar'd along with the image
and shows as expected when the jar is opened.
I have tested to see that it does work.
I do not know what, if anything, goes into the ()
of getImage(getClass().getResource())
to exctract only the image from the jar by itself,
so that the image can go into
another program in the same folder.
import java.awt.*;
import java.applet.Applet;
import java.awt.Image;
public class ImageAppletBriefX extends Applet
  {
  private Image ioStream;
  private String errorMessage = null;
  public void init() {
    try
      {
      // the jar containing the image is
      //"TestLoadImage.jar"
      // the image file in the jar is "JBsm.JPG"
      ioStream = getImage(getClass().getResource());
      // << the line in question is above
      repaint();
      }
    catch (Exception netProblem )
      {
      errorMessage = "Could not reach image";
      }
    }
  public void paint( Graphics display)
    {
    if ( errorMessage == null )
      display.drawImage( ioStream, 0, 0, this );
    else
      display.drawString( errorMessage, 10, 10 );
    }
  }
Thanks for your help up to this point
bH

I'm not exactly clear what your problem is here. But I will give you a
complete example. Assume you have an image file named "kittens.jpg" and
you want to display it in your Applet. Furthermore you want to deploy
your Applet from a .jar file with the code and image store in the .jar.

import java.applet.*;
import java.awt.*;

public class test1 extends Applet {
     Image image;

     public void init() {
         image = getImage(getClass().getResource("kittens.jpg"));
     }

     public void paint(Graphics g) {
         g.setColor(Color.RED);

         if (!g.drawImage(image,0,0,this))
             g.drawString("Loading Image",10,20);
     }

}

Compile the code above. Jar up the file with the following command;

jar cvfM test1.jar test1*.class kittens.jpg

This stores all class files from the test1 class and the image file into
the jar.

<html>
     <head>
     </head>
     <body>
         <applet archive="test1.jar" code="test1.class"
          width="640" height="480">
         </applet>
     </body>
</html>

Create the html file above, I called mine test1.html.

Now run the appletviewer or load the html file with your browser;

appletviewer test1.html

The appletviewer/browser will load the .jar file and run the
test1.class, reading the kittens.jpg image file from the .jar and
displaying it. Until the image is completely loaded the message
"Loading Image" will be drawn onto the Applet as well.

You do not need a repaint() call if you are using the
ImageProducer/ImageObserver scheme.

If that is not what you needed, then please post again.

--

Knute Johnson
email s/nospam/linux/

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Hi Knute,
I was able to accomplish your html model above earlier
and it did show the image as the original applet did,
Thank you for your html gift above.

Now for the rest of it. I was hoping that I might extract the
image "kittens.jpg" ONLY from the "test1.jar" and use the
the image in another applet. All be it by coding differently in a
second
applet, and make "kittens.jpg" appeared as coming from the jar.

I guess that what I was trying to do was make some sense out of
what Mark Space was saying above....
"Make this image into a resource, and use
getResourceAsStream(). That's the correct way to package extra files
with an applet."
Can this be changed to reflect getting the image from the jar?
image = getImage(getClass().getResource("kittens.jpg"));


getResourceAsStream() just gets you the image data in a stream as
opposed to the URL. That won't help you with your question.

Any possibility of coding to get just the image ("kittens.jpg") into
another applet using that with the idea that Mark Space is saying.
If that is not what he was suggesting then there is nothing more.

Thanks for your prompt reply.

bH


Yes. You can specify many .jar files in the ARCHIVE parameter of the
APPLET tag. Just separate them with commas.

<html>
     <head>
     </head>
     <body>
         <applet archive="test1.jar,test2.jar" code="test2.class"
          width="640" height="480">
         </applet>
     </body>
</html>

The HTML above loads both the test1.jar and test2.jar and runs the class
test2. The code for test2.java is almost the same as test1.java.

import java.applet.*;
import java.awt.*;

public class test2 extends Applet {
     Image image;

     public void init() {
         image = getImage(getClass().getResource("kittens.jpg"));
     }

     public void paint(Graphics g) {
         g.setColor(Color.BLUE);

         if (!g.drawImage(image,0,0,this))
             g.drawString("Loading Image",10,20);
     }
}

--

Knute Johnson
email s/nospam/linux/

--
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