Java Socket Programming

src/
├── main/
│   ├── java/com/example/
│   │   ├── controller/
│   │   ├── service/
│   │   ├── repository/
│   │   ├── model/
│   │   └── config/
│   └── resources/
│       └── application.yml
└── test/

<dependencies>
    <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.springframework.boot</groupId>
        <artifactId>spring-boot-starter-validation</artifactId>
    </dependency>
</dependencies>

@Entity
@Table(name = "resources")
public class Resource {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotBlank(message = "Name is required")
    @Size(max = 255)
    private String name;

    @Column(columnDefinition = "TEXT")
    private String description;

    @Enumerated(EnumType.STRING)
    private Status status = Status.ACTIVE;

    @CreationTimestamp
    private LocalDateTime createdAt;

    // Getters, setters, constructors
}

@Service
@Transactional
public class ResourceService {
    private final ResourceRepository repository;

    public ResourceService(ResourceRepository repository) {
        this.repository = repository;
    }

    public List<Resource> findAll() {
        return repository.findAll(Sort.by(Sort.Direction.DESC, "createdAt"));
    }

    public Resource findById(Long id) {
        return repository.findById(id)
            .orElseThrow(() -> new ResourceNotFoundException("Resource not found: " + id));
    }

    public Resource create(ResourceRequest request) {
        Resource resource = new Resource();
        resource.setName(request.getName());
        resource.setDescription(request.getDescription());
        return repository.save(resource);
    }
}

@RestController
@RequestMapping("/api/resources")
public class ResourceController {
    private final ResourceService service;

    @GetMapping
    public ResponseEntity<List<Resource>> getAll() {
        return ResponseEntity.ok(service.findAll());
    }

    @PostMapping
    public ResponseEntity<Resource> create(@Valid @RequestBody ResourceRequest request) {
        Resource created = service.create(request);
        return ResponseEntity.status(HttpStatus.CREATED).body(created);
    }

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleNotFound(ResourceNotFoundException ex) {
        return ResponseEntity.status(HttpStatus.NOT_FOUND)
            .body(new ErrorResponse(ex.getMessage()));
    }
}