Annotation Processing

Building a Java Annotation Processor.

We look at runtime and compile time annotation processing.

Transcript

1. Annotation Processing Building a Java Annotation Processor Corneil du Plessis
2. Agenda • What are annotation processors? • How can we use annotation processors? • How do we build an annotation processor?
3. Java Annotations – A Primer • Annotations are Class metadata • Annotations can be used at runtime. • Annotations can be used at compile time.
4. Annotation Processors – Why? • Generate source code or resources. • Modify existing source. • Analyse existing code to provide diagnostic feedback.
5. The Problem
6. Solution
7. Example of Use
8. Performing the check
9. How – RequiresStatic annotation
10. RequiresStaticSupport.checkClass
11. RequiresStaticSupport.checkClass continued
12. RequiresStaticSupport.checkClass continued
13. RequiresStaticSupport.checkClass continued
14. RequiresStaticProcessor
15. Annotation Processor META-INF • File named META-INF/services/javax.annotation.processing.Processor • Content is fully qualifed names of annotation processors.
16. RequestStaticProcessor Source Let’s look at the code.
17. Debugging your Annotation Processors • Add Compiler option: -Xdebug - agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=7777 • Debug remote (Attach) with options: -Xdebug - agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=7777 • Set break point on process method. • Build will pause so that you can attach debugger.
18. Finally • Contact: @corneil • Source Code - https://github.com/corneil/static-requirements • Resources • https://www.javacodegeeks.com/2015/09/java-annotation-proc essors.html • http://hannesdorfmann.com/annotation-processing/annotation processing101 Questions?