How to prohibit usage of classes with certain annotation

user_8587028 0
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In our organizations we've got several microservices and lots of libraries.

Some libraries define "public" classes that are not intended for public usage - only inside library in multiple packages (thus can't be package-private)

I'd like to add something similar to Kotlin's "internal" modifier - a checkstyle rule/annotation processor/test component that verifies that consumer applications don't import these classes.

for example, I will mark them as @ForInternalUsageOnly or put into package com.ourorg.mylib.internal_usage

what can be a non-copy-pasted (e.g. a jar or a gradle task) implementation that verifies that such classes are not imported? Preferably - on compilation level

archunit pmd checkstyle java
2 Answers

It sounds like you should be using the Java 9+ module feature, and its ability specify what classes are exposed outside of a given module.

Here are some references to get you started:

and there are lots of tutorials and videos.

While it should be possible to do what you propose using annotations and a checker, I can't recommend any practical examples.

user_1399850

You can achieve something like this with ArchUnit easily, your ArchRule would be something like -

@ArchTest                                                  
public static final ArchRule customArchRule = noClasses()   
    .should()                                               
    .dependOnClassesThat()                                  
    .areAnnotatedWith(ForInternalUsageOnly.class);

Assuming you are using it with JUnit 5 or 4, classes in noClasses() are determined by @AnalyzeClasses, you can read more about setting up and using ArchUnit from here.

user_154123650
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