Spring Boot #2 — CRUD with REST API · Layered Architecture · Global Exception Handler
Following Spring Boot #1 (first run · DI), #2 covers CRUD with REST API. Starting from the definition that REST is a combination of URL + HTTP method (GET/POST/PUT/DELETE), I completed todos CRUD by attaching @GetMapping · @PostMapping · @PutMapping · @DeleteMapping to the controller. I organized curl options (-X method · -H format · -d data) and verified the flow with a 5-step curl sequence (create → list all → update → delete → final check). Since the controller was holding all the logic, I split it into a service → layered architecture (Controller = request/response / Service = logic / Repository = storage). For exception handling: custom exception → 404 response, and with a Global Exception Handler in place, the controller just throws while the handler takes care of the response mapping — extending into practice the "throw forces propagation" contract I learned in the Java #3 post. Two trial-and-error incidents (trying to start the server without a referenced class present · writing package code before adding the library) got folded into my study guidelines to prevent recurrence.
