Articles

"From Java to Spring Boot" 0–5

The first cycle: from the Java of a course to your first application on Spring Boot 4, with a database, endpoints, and tests.

1. 0What to know before Spring

   Records, enums with a code, unchecked exceptions, Maven, and table-driven tests on JUnit 6: what to know before your first Spring application.

   20–25 min read

2. 1Why Spring

   Wire an application by hand, then let the Spring container do it: constructor injection, beans, @Component, @Configuration, @Bean.

   30 min read

3. 2Spring Boot 4 for absolute beginners

   How Spring Boot 4 starts: auto-configuration, embedded Tomcat, the new starters, settings from YAML, profiles and the environment, checks at startup.

   25 min read

4. 3aData, part 1: a table and a migration

   A SQL table that guards its own rules, Flyway migrations, and a migration test against a real Postgres in Docker.

   30 min read

5. 3bData, part 2: entity, repository, transaction

   How a Java object becomes a table row, an all-or-nothing transaction, and a test against a real database.

   30 min read

6. 4Your first endpoint: how an application answers over HTTP

   HTTP and curl, a controller and JSON, errors as responses, and a web layer test with a Mockito mock, no database needed.

   35 min read

7. 5The full endpoint: layers, access, paging, tests on every layer

   Layers and records instead of entities, paged lists, sign-in and roles with Spring Security, and tests for every layer.

   45 min read