Installing JNLP on Ubuntu for Open JDK 7

问题

How do I get JNLP working for OpenJDK 7 on a Ubuntu machine?

I'm trying to get the source code linked to at http://www.bugaco.com/bioinf/clusterer/ with the text "Download sources" to run on my machine.

Currently, when I try running

javac -cp ".:l2fprod-common-all-7.3.jar:jfreechart-1.0.17/lib/jfreechart-1.0.17.jar" com/bugaco/mioritic/impl/module/project/Main.java

it is giving me the error

./com/bugaco/ui/LoadBean.java:11: error: package javax.jnlp does not exist
import javax.jnlp.FileOpenService;
                 ^

(and many other errors)

which I assume indicates that I need to install JNLP, along with other packages I'll have to install when I get JNLP fixed.

Based on Mike Clark's answer https://stackoverflow.com/a/12608844/38765 I assumed that "Demos and Samples" is the way to install JNLP for Open JDK 7.

I'm on Ubuntu, so I'm trying to use the "Ubuntu way" to install it. I installed openjdk-7-demo , which describes itself as "Java runtime based on OpenJDK (demos and examples)".

It's still giving the error described above. What have I done wrong, or forgotten to do?

I tried browsing the tag wiki for java. The only non-video resource that looked relevant to me in "Beginners' resources" was "The Java Tutorials". The only link relevant from there was "Learning the Java Language". It had a section on packages, but that's only on how to create your own, rather than how to install other peoples' packages.

I'm using Ubuntu 12.04 (precise) 64-bit, and Java 7

java version "1.7.0_55"
OpenJDK Runtime Environment (IcedTea 2.4.7) (7u55-2.4.7-1ubuntu1~0.12.04.2)
OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)