If I want to build a site with PHP, all I have to do is install the PHP package and make sure mod_php is enabled in my apache web server. Voila! a PHP environment.
Now, if I want to build a site with equivalent Java tech, i.e. JSP and Servlets, What do I have to install?
You only have to install Java (usually already done) and a servlet container like Tomcat.
Netbeans locally includes all startconfig and sample projects needed and you can deploy to gae or eatj. It's complicated and worth the effort. You can go with gae or custom your own with jetty, tomcat, jboss, websphere or glassfish. 512 RAM was minimal after trying with 256 which permgened. You might try with 256. I recommend avoid EJB and custom tags and keep web archives instead of enterprise archives for small to medium projects.
You will need a Java Web Container (Tomcat is a good starting point) plus needing to tell your Apache frontend how to reach the web container from the outside.
Note, most modern Java Web Containers can perform well enough to not need a frontend Apache server.
You need to install the Java Environment, where a web server, The code which does the appropriate functions.
You will be using the jsp for the view part Servlets for the Basic modal part, where you will write the business logic and Web.xml, is the deployment descriptor where you will tell the server aabout the servlets and jsp and how the control of the flow will be defined