source: trunk/doc/tomcat_with_java_1.5.txt @ 732

How to configure Tomcat to use Java 1.5
=======================================

The new Tomcat 5.5 comes with it's own compiler, which is not
Java 1.5 compatible. Here are the instructions to replace the
built-in compiler with Sun's compiler.

It requires that you have downloaded and installed Java 1.5 SDK
and Ant.

* Copy "tools.jar" from JAVA_HOME/lib to TOMCAT_HOME/common/lib

* Copy "ant.jar" from ANT_HOME/lib to TOMCAT_HOME/common/lib

* Remove "jasper-compiler-jdt.jar" from TOMCAT_HOME/common/lib

* Open the file "TOMCAT_HOME/conf/web.xml" and locate the place
  that says:
  
    <servlet>
        <servlet-name>jsp</servlet-name>
        <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
        <init-param>
            <param-name>fork</param-name>
            <param-value>false</param-value>
        </init-param>
        <init-param>
            <param-name>xpoweredBy</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>3</load-on-startup>
    </servlet>
   
   Add two new <init-param> tags:

        <init-param>
            <param-name>compilerSourceVM</param-name>
            <param-value>1.5</param-value>
        </init-param>
        <init-param>
            <param-name>compilerTargetVM</param-name>
            <param-value>1.5</param-value>
        </init-param>

Restart the Tomcat web server. Everything should now work.

More information can be found on (this very ugly URL):
http://blog.taragana.com/index.php/archive/how-to-run-javac-15-or-beyond-compiler-for-jsp-compilation-in-tomcat-55-with-generics-enabled-and-other-15-only-features/