Revealing the Magic Behind Java Annotations
summary
Explains how Java annotations (since Java 5) are used by frameworks like Spring, Hibernate and Micronaut for things like dependency injection, persistence and code generation, and shows concrete examples of annotation processing both at runtime via reflection and at compile/build time using the Annotation Processing API and build-time techniques (e.g., Lombok, Dagger). Álvaro Sánchez-Mariscal, a Micronaut committer, demonstrates how these mechanisms work and what happens when the compiler encounters an annotation.
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chapters (11)
- 0:00Introduction and speaker intro
- 3:57Runtime annotation processing explained
- 13:17Runtime bytecode manipulation tools
- 20:36Compile-time annotation processing
- 23:05Annotation Processing API basics
- 28:55Lombok technical limitations
- 31:05Micronaut framework overview
- 32:29Micronaut build-time processing
- 36:50Startup time and memory benefits
- 38:38Cloud-native and serverless advantages
- 40:05Q&A session
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