Abhishek Mahanty's Weblog

Java Plugin for Firefox on Linux

I hit a page that had a Java applet and got the following "Missing Plugin" message.

Basically, my browser - firefox was unable to locate a Java Plugin needed to execute the applet on the page. It also gave me an option to "install the missing plugin" which essentially involved downloading a complete JRE which would take time. However, since I already had the latest JRE installed on my system, this is how I went about configuring firefox to use the same.

1. View the contents of the firefox plugins folder to look for existing/older Java plugins (if any)

abhi@abhiltlnx(~)$ type firefox
firefox is /usr/bin/firefox

abhi@abhiltlnx(~)$ ls -ll /usr/bin/firefox
lrwxrwxrwx 1 root root 25 2008-02-08 03:05 /usr/bin/firefox -> ../lib/firefox/firefox.sh

abhi@abhiltlnx(~)$ ls -lth /usr/lib/firefox/
total 12M
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 icons
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 plugins
drwxr-xr-x 6 root root 4.0K 2008-02-08 03:05 res
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 searchplugins
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 greprefs
drwxr-xr-x 3 root root 4.0K 2008-02-08 03:05 chrome
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 components
drwxr-xr-x 5 root root 4.0K 2008-02-08 03:05 defaults
drwxr-xr-x 2 root root 4.0K 2008-02-08 03:05 dictionaries
drwxr-xr-x 5 root root 4.0K 2008-02-08 03:05 extensions
-rwxr-xr-x 1 root root 9.4M 2007-09-25 00:22 firefox-bin
-rwxr-xr-x 1 root root  14K 2007-09-25 00:22 mozilla-xremote-client
-rwxr-xr-x 1 root root 107K 2007-09-25 00:22 libxpcom_compat.so
-rwxr-xr-x 1 root root 798K 2007-09-25 00:22 libxpcom_core.so
-rwxr-xr-x 1 root root 9.6K 2007-09-25 00:22 libxpcom.so
-rwxr-xr-x 1 root root  14K 2007-09-25 00:22 libxpistub.so
-rwxr-xr-x 1 root root  62K 2007-09-25 00:22 updater
-rwxr-xr-x 1 root root 621K 2007-09-25 00:22 libmozjs.so
-rwxr-xr-x 1 root root  22K 2007-09-25 00:22 xpicleanup
-rw-r--r-- 1 root root  158 2007-09-25 00:22 browserconfig.properties
-rwxr-xr-x 1 root root 6.1K 2007-09-25 00:22 firefox.sh
-rw-r--r-- 1 root root  177 2007-09-25 00:19 readme.txt
-rwxr-xr-x 1 root root  11K 2007-09-25 00:19 run-mozilla.sh
-rw-r--r-- 1 root root  145 2007-09-25 00:19 updater.ini

abhi@abhiltlnx(~)$ ls -lth /usr/lib/firefox/plugins/
total 24K
-rwxr-xr-x 1 root root 22K 2007-09-25 00:22 libnullplugin.so
      

2. Locate the Java plugin library file in the installed JDK/JRE
The java plugin file will be - $JRE_HOME/jre/plugin/i386/ns7/libjavaplugin_oji.so

abhi@abhiltlnx(~)$ type java
java is hashed (/usr/bin/java)
abhi@abhiltlnx(~)$ ls -ll /usr/bin/java
lrwxrwxrwx 1 root root 30 2008-02-17 06:22 /usr/bin/java -> /opt/java/jdk1.6.0_04/bin/java
abhi@abhiltlnx(~)$ cd /opt/java/jdk1.6.0_04/
abhi@abhiltlnx(/opt/java/jdk1.6.0_04)$ ls -lth jre/plugin/i386/ns7/
total 140K
-rwxr-xr-x 1 root root 134K 2007-12-14 15:04 libjavaplugin_oji.so
abhi@abhiltlnx(/opt/java/jdk1.6.0_04)$         
      

3. Create a soft/symbolic link to the java plugin file in the firefox plugins folder.
Note: root access needed... use sudo.

abhi@abhiltlnx(/opt/java/jdk1.6.0_04)$ sudo ln -s jre/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/firefox/plugins/
root's password:

abhi@abhiltlnx(/opt/java/jdk1.6.0_04)$ ls -lth /usr/lib/firefox/plugins/
total 28K
lrwxrwxrwx 1 root root  62 2008-02-26 00:54 libjavaplugin_oji.so -> /opt/java/jdk1.6.0_04/jre/plugin/i386/ns7/libjavaplugin_oji.so
-rwxr-xr-x 1 root root 22K 2007-09-25 00:22 libnullplugin.so
abhi@abhiltlnx(/opt/java/jdk1.6.0_04)$ 
        
      

Exit and restart firefox. You should be able to view the applet on the page.

If you have any issues, make sure that Java has been enabled in the content tab of the firefox preferences dialog (Edit -> Preferences -> Content)

4. View Java Console

In order to view any System.out or System.err messages from the applet, configure the Java Control Panel

abhi@abhiltlnx(/opt/java/jdk1.6.0_04/bin)$ javaws -viewer &
[1] 14233
abhi@abhiltlnx(/opt/java/jdk1.6.0_04/bin)$     
      

Restart firefox and now when an applet gets executed, you'll view the Java Console with all the messages.

Resources:

• Java SE6 Release Notes: Manual Installation and Registration of Linux Plugin
• How To use Java with Firefox on 64-bit openSuSE 10.3

To learn more:

• About Java Applets - Applets lesson from Java Tutorials
• About Java Plugins - Java Plugin Guide

Posted at 12:00AM Feb 24, 2008 by Abhishek Mahanty in Technical  |  Comments[2]