Manually Setup JRE
Go to the Java website, choose the JRE based on your platform, download the requisite .bin files and upload them to your home folder:
su - serveradmin # If you are not already serveradmin cd ~ # Switch to the serveradmin home directory chmod +x jre-6u16-linux-i586.bin ./jre-6u14-linux-i586.bin # Decompresses JRE to the current folder under jre1.6.0_16. mv ./jre1.6.0_16 ./java mkdir apache mv ./java ./apache/
Shawn took an interesting approach and further stripped down Tomcat. Ask him for details on this.
The purpose of the serveradmin account is to run Tomcat and java. As such serveradmin can not sudo into root. In the event that Tomcat is somehow attacked serveradmin would be compromised. Not allowing serveradmin access to sudo provides an extra layer of security.
Log in as your staff account which has sudo access to perform the actual move to /opt/
cd /home/serveradmin sudo mv ./apache/ /opt/
If you go with 64-bit Java (which I recommend against as it's way slower right now) I find it useful to add to the default folder name _64-bit so in that case it would be, jre1.6.0_16*_64-bit*.
For Solaris, use the sh file, and move it into opt and run it.
You can also do something very similar with my Windows instructions.
For older versions go to the Java Archives site.