[ previous ] [ Contents ] [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] [ A ] [ next ]

Debian GNU/Linux Java FAQ.
Chapter 10 - Java Plugins for Browsers

The following section describes how you can use Java in web browsers in order to be able to run applets published in web servers.

10.1 Can I use any JVM as a Java Plugin?

That is a tricky question. My answer would be: "No, but it doesn't hurt trying" (and don't forget to forward us your findings so we can update this document)

10.2 Can I use Java in Konqueror?

Yes, in Konqueror 3.1.1, you Settings->Configure Konqueror. The opened Control Module has a Java&JavaScript section where you can enter the location of your JVM. The configuration should look like this:

As it says /usr/bin/java it relies on the update-alternatives mechanism to point to a JVM that can serve as a plugin. If you have Sun's J2RE installed, "Path to Java" might also say something like /usr/local/lib/j2sdk1.4.2/jre/bin/java

10.3 Can I use Java in Netscape 6.x/7.x?

Yes. Make a symbolic link in the /path/to/netscape/plugins directory to the Java Plugin as can be found in Sun's J2RE:

     /usr/local/netscape/plugins $ ls -la
     total 960
     drwxr-sr-x    2 root     staff        4096 Apr 30 09:46 .
     drwxr-sr-x    9 root     staff        4096 Apr  8 20:26 ..
     -rw-r--r--    1 root     staff        2363 Feb  8 07:47 ShockwaveFlash.class
     -rw-r--r--    1 root     staff      946108 Feb  8 07:47 libflashplayer.so
     lrwxrwxrwx    1 root     staff          64 Apr 30 09:46 libjavaplugin_oji.so -> /usr/local/lib/j2sdk1.4.2/jre/plugin/i386/ns610-gcc32/libjavaplugin_oji.so
     -rwxr-xr-x    1 root     staff       19396 Feb  8 07:47 libnullplugin.so

If you have Blackdown's J2RE installed the link has to be made to /usr/lib/j2se/1.4/jre/plugin/i386/mozilla/javaplugin_oji.so. Other possible locations include /usr/java/j2re1.4.2_04/plugin/i386/ns610-gcc32/libjavaplugin_oji.so, you will need to locate this plugin depending on your installation.

10.4 Can I use Java in Mozilla?

Yes, the mechanism is identical to that of Netscape. However, the plugin directory in this case is /usr/lib/mozilla/plugins. There is additional information on how to install Java in Mozilla at the Java FAQ at Mozilla

There might be some issues depending on your version. Mozilla 1.4 and later (as well as Mozilla Firebox) is compiled with gcc 3.x and needs a compatible version of the plugin, as provided by JRE 1.4.2 or later. If you find issues you will need to debug yourself. A common problem is that the library might not be binary compatible if it was compiled with a different gcc version. Some gory details on how to debug this are described below (contributed by Tim Freeman and included in the #debian faq wiki)

The first problem is that in version 1.6-5 of the mozilla-browser package, at least, /usr/bin/mozilla is a shell script that redirects errors to /dev/null. This is described in bug 178271

To deal with this, make a copy of /usr/bin/mozilla and edit out the redirects of file descriptor 2 to /dev/null and run the copy. You may see something like this on Mozilla's standard error when it starts:

     LoadPlugin: failed to initialize shared library /usr/lib/j2se/1.3/jre/plugin/i386/mozilla/javaplugin_oji.so [/usr/lib/j2se/1.3/jre/plugin/i386/mozilla/javaplugin_oji.so: undefined symbol: __vt_17nsGetServiceByCID]

This symptom indicates that your Java was compiled with an old version of GCC, but your Mozilla was compiled with a newer version (post gcc 3.0.3), and the two are binary incompatible. This is the case for version of the j2re1.3 package from ftp://ftp.tux.org, at least.

If you're confronted with this symptom, the fix is to get a Java runtime that was compiled with a more recent gcc. There are several available; one is ftp://ftp.tux.org/pub/java/JDK-1.4.2/i386/01/j2re-1.4.2-01-linux-i586.bin. Install that and change the libjavaplugin_oji.so link to point into the newly installed Java runtime.

If you wish to confirm the diagnosis before attempting the above treatment, you can do it as follows. Confirm that your Java was compiled with the old gcc by giving the command:

           c++filt -s gnu __vt_17nsGetServiceByCID

and getting the result:

            nsGetServiceByCID virtual table

To confirm that your mozilla was compiled with the new gcc, you can find its version of the symbol by giving the command:

        objdump -R /usr/lib/libxpcom.so | grep nsGetServiceByCID

and you'll see a line like:

          000ec114 R_386_GLOB_DAT _ZTV17nsGetServiceByCID

Then you demangle that with the command:

         c++filt -s gnu-v3 _ZTV17nsGetServiceByCID

and get this eminently reasonable output:

         vtable for nsGetServiceByCID

The important thing is that the two calls to c++filt both succeeded but they were told to use different demangling rules, "gnu" for the first and "gnu-v3" for the second. If this all checks out, then you should fetch a newer Java runtime as described above.

[ previous ] [ Contents ] [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] [ A ] [ next ]

Debian GNU/Linux Java FAQ.

$Revision: 1.57 $ 4 August 2009Sunday, 4th November

Javier Fernández-Sanguino Peña jfs@debian.org