REST endpoint katika Spring Boot ni method kwenye @RestController, iliyounganishwa na HTTP verb na path. @RestController = @Controller + @ResponseBody, hivyo thamani zinazorudishwa hu-serialize moja kwa moja hadi response body (JSON kupitia Jackson) badala ya kusuluhishwa kuwa view.
@RestController
@RequestMapping("/api/users") // base path for every method below
public class UserController {
private final UserService service;
public UserController(UserService service) { this.service = service; }
@GetMapping("/{id}") // GET /api/users/42
public UserDto get(@PathVariable Long id) { // bind {id} from the URL
return service.findById(id); // returned object -> JSON
}
@PostMapping // POST /api/users
@ResponseStatus(HttpStatus.CREATED) // 201 instead of 200
public UserDto create(@Valid @RequestBody UserDto body) { // JSON -> object
return service.create(body);
}
@GetMapping // GET /api/users?role=admin
public List<UserDto> list(@RequestParam(required = false) String role) {
return service.findByRole(role);
}
}
Annotations muhimu: @PathVariable huvuta thamani kutoka kwa path, @RequestParam husoma parameter ya query-string, na @RequestBody hu-deserialize JSON payload. Kuongeza @Valid huchochea Bean Validation (@NotNull, @Email…) kwenye DTO inayoingia kabla method yako haijakimbia.
@GetMapping("/{id}")
public ResponseEntity<UserDto> get(@PathVariable Long id) {
return service.find(id)
.map(ResponseEntity::ok) // 200 + body
.orElse(ResponseEntity.notFound().build()); // 404, no body
}
Hii ni kazi ya msingi ya backend, hivyo wahoji hutarajia ufasaha. Majibu imara hutaja kutumia DTOs badala ya kuweka wazi JPA entities, kuthibitisha input kwa @Valid, na kurudisha status codes sahihi kwa ResponseEntity — tofauti kati ya endpoint ya kuchezea na API halisi.
Maktaba ya maswali ya mahojiano ya IT yenye majibu ya kina — kutoka Junior hadi Senior.
Changia