In this I’ll discuss a uncommonly used but useful technique of accessing variables and methods which have been declared as private in the JVM, using the Apache Commons Lang library to work around the restriction. The description from the project page reads:
The standard Java libraries fail to provide enough methods for manipulation of its core classes. Apache Commons Lang provides these extra methods.
A couple weeks ago I was working on a project that required parsing some CQL statements. There isn’t a standard parser separate from the Cassandra project at the moment, so I decided to pull in the entirety of cassandra-all from maven central. The parser in Cassandra isn’t really designed to be used as a library. In particular, the org.apache.cassandra.cql3.QueryProcessor has a parseStatement(String) call, but the ParsedStatement that’s returned doesn’t expose any of the private variables via getters. I felt particularly determined for some reason, so I decided to investigate a workaround.
I tried Python out a while ago, but stopped trying it to learn it after some major frustrations. Maybe I didn’t dig deep enough into it. I found the documentation hard to read, and the module layout seemed a little random at times. For some reason I found executing an external process and getting the results to be a little convoluted. (Since then I’ve learned to use popen(..).communicate())
I ended up messing with other languages to try to find one that suits my tastes, like Erlang and D. I read through 7 languages in 7 weeks, and not really getting a lot out of it. I didn’t fall in love with ruby at all and I’m not going to actually use Prolog anywhere, even if I thought it was pretty cool. I never liked Java, and I wasn’t impressed with Scala.
I’m going to go through the steps necessary to install and start using Solr. I’ve always been interested in trying out Lucene, but I never felt like dealing with writing my own wrapper around the classes. Solr simplifies this by creating a fully working search engine as a web service.
Let’s get started. You’ll need to check to see if Java is up to date. Run the below to find out.
