Preprocessing source code as a part of a maven build

Question

I have a lot of Java source code that requires custom pre-processing. I'd like rid of it but that's not feasible right now so I'm stuck with it. Given that I have an unfortunate problem that shouldn't have existed in the first place, how do I solve it using maven?

(For the full story, I'm replacing a python-based build system with a maven one, so one improvement at a time please. Fixing the non-standard source code is harder, and will come later.)

Is it possible using any existing Maven plugins to actually alter the source files during compile time? (Obviously leaving the original, unprocessed code alone)

To be clear, by preprocessing I mean preprocessing in the same sense as antenna or a C compiler would preprocess the code, and by custom I mean that it's completely proprietary and looks nothing at all like C or antenna preprocessing.

Answer 1

This is something that is very doable and I've done something very similar in the past.

An example from a project of mine, where I used the antrun plug-in to execute an external program to process sources:

  <build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-antrun-plugin</artifactId>
      <executions>
        <execution>
          <id>process-sources</id>
          <phase>process-sources</phase>
          <configuration>
            <tasks>
               <!-- Put the code to run the program here -->
            </tasks>
          </configuration>
          <goals>
            <goal>run</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

Note the tag where I indicate the phase where this is run. Documentation for the lifecycles in Maven is here. Another option is to actually write your own Maven plug-in that does this. It's a little more complex, but is also doable. You will still configure it similarly to what I have documented here.