Install sunjdk7 in ubuntu, and install jre in firefox22.

Unzip, unzip: tar-xvzfjdk-7u25-linux-i586.gz copy to/usr/lib/jvm: sudocp-rfjdk1.7.0_25/usr/lib/jvm change environment variable: install sun jdk7 under gedit ubuntu, firefox22 install jre installation package is jdk-7u25-linux-i586.gz, unzip: tar-xvzf jdk-7u25-linux-i586.gz copy to/usr/lib/jvm: sudo cp-rf jdk1.7.0 _ 25/usr/lib/jvm change environment variable: gedit ~ /. Open bashrc and add: export JAVA_HOME =/usr/lib/jvm/jdk1.7.0 _ 25 export JRE_HOME =$ {JAVA_HOME}/jre export CLASSPATH =.: $ {JAVA_HOME}/lib :$ {JRE_HOME}/lib export PATH =$ {JAVA_HOME}/bin: $ PATH save closed. Use source to make it take effect: source ~ /. Bashrc and then java-version will see that the java version is 7. the firefox12's installation package is firefox-latest.tar.bz2. after the package is decompressed, it is a firefox Directory. delete the old firefox: sudo rm-r/opt/firefox and move the decompressed version to the directory: sudo mv firefox/opt/back up the link of the old firefox in the system: sudo mv/usr/bin/firefox-old create link for firefox12 sudo ln-s/opt/firefox/usr/bin/firefox and fill in add java plugin to support java 7. in the URL box of firefox, enter "about: plugins: check the current position of the plugin. here is/usr/lib/mozilla/plugins. disable Firefox. Enter the directory cd/usr/lib/mozilla/plugins and enter the link: sudo ln-s/usr/lib/jvm/jdk1.7.0 _ 25/jre/lib/i386/libnpjp2.so Open firefox and you will see that java plugin has been installed.