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javapoet (for generating code in Java): square/javapoet: A Java API for generating .java source files. (github.com)

Resources: 1. Spring Boot Official Documentation on configuring multiple data sources: Spring Boot Reference Documentation 2. javapoet (for generating code in Java): square/javapoet: A Java API for generating .java source files. (github.com) 3. Guide to Annotation Processing in Java: Java Annotation Processing and Creating a Builder | Baeldung

Javapoet. This helped me a lot, because i wrote two generators, one for one employer, who don't like dynamic generators, so the first was to generate mappers like mapstruct does; from model to pojos and viceversa. The second one was a static testing pojo factory generator; this last one i made public (it's pretty basic and now we have projects like instancio and podam) its name is mother-factory.

> can you show an example of how you'd parse, say, a .java.in

The canonical way to do such a thing is through the java annotation processing api [1] and using a tool like java poet [2]. Before you did that, you'd probably decide if you wanted to instead use bytecode generation with a library like bytebuddy [3]

But, assuming for some reason, you wanted to torture yourself and actually consume a java.in file and apply a regex, then you'd probably pull out the "maven-replacer-plugin" [4] and configure that for the task at hand. (or use your favorite templating language plugin. There's a million of them).

Though, to be fair, this really isn't something that comes up in regular java programming due to the nature of the ecosystem. Anything you'd want to codegen likely already has a library and anything you didn't would receive (legitimate) push back.

[1] https://www.baeldung.com/java-annotation-processing-builder

[2] https://github.com/square/javapoet

[3] https://bytebuddy.net/

[4] https://github.com/beiliubei/maven-replacer-plugin

I’ve used a maven archetype before with velocitemplate. That solution was iffy so we then migrated to using https://github.com/square/javapoet to generate the java source and write it to the desired files. I think we also used the google formatter library so the files would be formatted after generating.

JavaPoet