Tomcat: The Definitive Guide

Appendix A. Installing Java

There are at least a few Java Software Development Kits (SDKs) and Java Runtime Environments (JREs) available that will support Tomcat, depending on which operating system you run. To run Tomcat, you need a Java 2 Standard Edition (J2SE) SDK. You need a Java compiler to use JavaServer Pages. If you do not wish to use JSP, you can use a J2SE JRE instead of a J2SE SDK. See Sun’s J2SE home page (http://java.sun.com/j2se) for more information about what the J2SE includes.

Each SDK includes a JRE, but if you download a JRE by itself, then you do not also have an SDK. The difference is that an SDK includes tools such as a Java compiler, debugger, and profiler, in addition to a runtime environment.

The J2SE SDKs we tested include Sun’s HotSpot J2SE 1.4.1, IBM’s 1.4.0 JDK, BEA’s JRockit 8.0 J2SE 1.4.1, and Apple’s J2SE 1.4.1. They each worked very well for us. Tomcat also works on Versions 1.2 and 1.3 of Java, so you may decide to use 1.2 or 1.3, but this may complicate things (minor complications that are mentioned throughout this book). Choose an SDK, and then read and follow the installation documentation for the one you choose.

For Tomcat to use a Java SDK, you just need to make sure that the JAVA_HOME and PATH environment variables are set appropriately. JAVA_HOME must be set to the full path of your SDK, and PATH must be set so that the first java binary found on PATH is the one you want to run. For example:

$ JAVA_HOME=/usr/local/j2sdk1.4.1_02 $ export ...