🚀 CRUD de Usuários com Spring Boot + JPA + PostgreSQL + Swagger

📘 Sumário

📂 Estrutura do Projeto

⚙️ Tecnologias Utilizadas

🐘 Configurando o Banco de Dados com Docker

# Passo 1: criar uma rede Docker isolada
docker network create backend-net
# Passo 2: subir Postgres + pgAdmin na mesma rede
docker run -d \
 --name postgress-test \
 --network backend-net \
 -p 5432:5432 \
 -e POSTGRES_USER=admin \
 -e POSTGRES_PASSWORD=admin123 \
 -e POSTGRES_DB=mydb \
 postgres:16
docker run -d \
 --name pgadmin \
 --network backend-net \
 -p 5050:80 \
 -e PGADMIN_DEFAULT_EMAIL=admin@admin.com \
 -e PGADMIN_DEFAULT_PASSWORD=admin123 \
 dpage/pgadmin4

🧩 Dependências Principais (pom.xml)

<dependencies>
 <!-- Web + JPA + PostgreSQL -->
 <dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
 </dependency>
 <dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-data-jpa</artifactId>
 </dependency>
 <dependency>
 <groupId>org.postgresql</groupId>
 <artifactId>postgresql</artifactId>
 </dependency>
 <!-- Swagger / OpenAPI -->
 <dependency>
 <groupId>org.springdoc</groupId>
 <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
 <version>2.8.13</version>
 </dependency>
</dependencies>

⚙️ Configuração do Spring Boot (application.properties)

spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=admin
spring.datasource.password=admin123
spring.datasource.driver-class-name=org.postgresql.Driver
spring.jpa.hibernate.ddl-auto=update
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
# Swagger
springdoc.api-docs.path=/api-docs
springdoc.swagger-ui.path=/swagger-ui.html

🧠 Arquitetura e Código-Fonte

🧩 Entidade (UserEntity.java)

@Entity
@Table(name = "users")
public class UserEntity {
 @Id
 @GeneratedValue
 private UUID id;
 @Column(nullable = false)
 private String name;
 @Column(nullable = false)
 private int age;
 @Version
 @Column(nullable = false)
 private Long version = 0L;
 public UserEntity() {}
 public UserEntity(String name, int age) {
 this.name = name;
 this.age = age;
 }
 public UserDTO toDTO() {
 return new UserDTO(id, name, age);
 }
}

🧾 DTO (UserDTO.java)

public record UserDTO(UUID id, String name, int age) {}

💾 Repository (UserRepository.java)

public interface UserRepository extends JpaRepository<UserEntity, UUID> {}

⚙️ Service (UserService.java)

@Service
public class UserService {
 private final UserRepository repo;
 public UserService(UserRepository repo) {
 this.repo = repo;
 }
 @Transactional
 public UserDTO create(String name, int age) {
 return repo.save(new UserEntity(name, age)).toDTO();
 }
 @Transactional(readOnly = true)
 public List<UserDTO> list(int page, int size) {
 Pageable pageable = PageRequest.of(page, size, Sort.by("id").descending());
 return repo.findAll(pageable).map(UserEntity::toDTO).toList();
 }
 @Transactional
 public UserDTO update(UUID id, String name, int age) {
 UserEntity user = repo.findById(id)
 .orElseThrow(() -> new EntityNotFoundException("Usuário não encontrado"));
 user.setName(name);
 user.setAge(age);
 return repo.save(user).toDTO();
 }
 @Transactional
 public void delete(UUID id) {
 if (!repo.existsById(id))
 throw new EntityNotFoundException("Usuário não encontrado");
 repo.deleteById(id);
 }
}

🌐 Controller (UserController.java)

@RestController
@RequestMapping("/api/users")
@Tag(name = "Usuários", description = "Gerenciamento de usuários")
public class UserController {
 private final UserService service;
 public UserController(UserService service) { this.service = service; }
 @Operation(summary = "Cria um novo usuário")
 @PostMapping
 public ResponseEntity<UserDTO> create(@RequestBody UserDTO req) {
 return ResponseEntity.status(HttpStatus.CREATED)
 .body(service.create(req.name(), req.age()));
 }
 @Operation(summary = "Lista usuários paginados")
 @GetMapping
 public ResponseEntity<List<UserDTO>> list(
 @RequestParam(defaultValue = "0") int page,
 @RequestParam(defaultValue = "50") int size) {
 return ResponseEntity.ok(service.list(page, size));
 }
 @Operation(summary = "Atualiza um usuário existente")
 @PutMapping("/{id}")
 public ResponseEntity<UserDTO> update(@PathVariable UUID id, @RequestBody UserDTO req) {
 return ResponseEntity.ok(service.update(id, req.name(), req.age()));
 }
 @Operation(summary = "Remove um usuário pelo ID")
 @DeleteMapping("/{id}")
 public ResponseEntity<Void> delete(@PathVariable UUID id) {
 service.delete(id);
 return ResponseEntity.noContent().build();
 }
}

🧾 Endpoints da API

🧭 Acessando o Swagger UI

http://localhost:8080/swagger-ui.html

🐞 Tratamento de Concorrência com @Version

org.hibernate.StaleObjectStateException