Spring Boot Tutorial 0/110 lessons ~6 min read Lesson 13“Production-grade backends”

Controllers

Controllers map HTTP requests to Java methods.

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Focus

3 guided sections

Practice signal

Examples included

Career prep

Foundation builder

Introduction

Controllers map HTTP requests to Java methods. @RestController = @Controller + @ResponseBody — every method's return value is auto-serialised to JSON.

Informative example

@RestController
@RequestMapping("/api/v1/users")
public class UserController {

  private final UserService users;
  public UserController(UserService users) { this.users = users; }

  @GetMapping
  public List<UserDto> list() { return users.findAll(); }

  @GetMapping("/{id}")
  public UserDto getOne(@PathVariable Long id) { return users.find(id); }

  @PostMapping
  @ResponseStatus(HttpStatus.CREATED)
  public UserDto create(@Valid @RequestBody NewUser cmd) {
    return users.create(cmd);
  }
}

Best practices

Version your APIs in the path: /api/v1/....
Return DTOs, never JPA entities, from controllers.
Pair every @PostMapping with @Valid.

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