REST

package at.aydin.lab.rest.legacy;

import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.net.URI;
import java.util.List;

@Path("books")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public class BookResource {
    private final BookRepository repository = BookRepository.instance();
    @GET
    public List<Book> all() {
        return repository.findAll();
    }

    @POST
    public Response create(Book book) {
        Book created = repository.save(book);
        return Response.created(URI.create("/api/books/" + created.getId())).entity(created).build();
    }
}

package at.aydin.lab.rest.modern;

import jakarta.validation.Valid;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;
import java.util.List;

@RestController
@RequestMapping("/api/books")
public class BookController {
    private final BookService service;
    public BookController(BookService service) {
        this.service = service;
    }

    @GetMapping
    public List<Book> all() {
        return service.findAll();
    }

    @PostMapping
    public ResponseEntity<Book> create(@Valid @RequestBody Book book, UriComponentsBuilder uriBuilder) {
        Book created = service.create(book);
        return ResponseEntity.created(uriBuilder.path("/api/books/{id}").build(created.id())).body(created);
    }
}

package at.aydin.lab.rest.modern;

import org.springframework.stereotype.Service;
import java.util.List;

@Service
// Design Pattern: Service Layer
// Zweck: Fachlogik bleibt unabhängig von HTTP.
public class BookService {
    private final BookRepository repository;
    public BookService(BookRepository repository) {
        this.repository = repository;
    }

    public List<Book> findAll() {
        return repository.findAll();
    }

    public Book create(Book book) {
        return repository.save(book);
    }
}

package at.aydin.lab.rest.legacy;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

// Design Pattern: Repository
// Zweck: Datenhaltung wird von der REST-Ressource getrennt.
public final class BookRepository {
    private static final BookRepository INSTANCE = new BookRepository();
    private final ConcurrentHashMap<Long, Book> books = new ConcurrentHashMap<>();
    private final AtomicLong sequence = new AtomicLong();
    private BookRepository() {
        save(new Book(0, "Enterprise Java verstehen"));
    }

    public static BookRepository instance() {
        return INSTANCE;
    }

    public List<Book> findAll() {
        return new ArrayList<>(books.values());
    }

    public Book save(Book book) {
        long id = book.getId() == 0 ? sequence.incrementAndGet() : book.getId();
        Book stored = new Book(id, book.getTitle());
        books.put(id, stored);
        return stored;
    }
}

package at.aydin.lab.rest.modern;

import org.springframework.stereotype.Repository;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

@Repository
// Design Pattern: Repository
// Zweck: Der Controller kennt keine Details der Datenhaltung.
public class BookRepository {
    private final ConcurrentHashMap<Long, Book> books = new ConcurrentHashMap<>();
    private final AtomicLong sequence = new AtomicLong();
    public BookRepository() {
        save(new Book(0, "Modernes Enterprise Java"));
    }

    public List<Book> findAll() {
        return List.copyOf(books.values());
    }

    public Book save(Book input) {
        long id = input.id() == 0 ? sequence.incrementAndGet() : input.id();
        Book stored = new Book(id, input.title());
        books.put(id, stored);
        return stored;
    }
}

package at.aydin.lab.rest.legacy;

public class Book {
    private long id;
    private String title;
    public Book() {
    }

    public Book(long id, String title) {
        this.id = id;
        this.title = title;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

package at.aydin.lab.rest.modern;

import jakarta.validation.constraints.NotBlank;

public record Book(long id, @NotBlank String title) {
}

package at.aydin.lab.rest.legacy;

import org.glassfish.grizzly.http.server.HttpServer;
import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;
import org.glassfish.jersey.jackson.JacksonFeature;
import org.glassfish.jersey.server.ResourceConfig;
import java.net.URI;

public final class RestLegacyApplication {
    private RestLegacyApplication() {
    }

    public static void main(String[] args) throws Exception {
        ResourceConfig config = new ResourceConfig(BookResource.class, JacksonFeature.class);
        HttpServer server = GrizzlyHttpServerFactory.createHttpServer(URI.create("http://localhost:8081/api/"), config);
        System.out.println("Legacy JAX-RS: http://localhost:8081/api/books");
        System.out.println("ENTER beendet den Server.");
        System.in.read();
        server.shutdownNow();
    }
}

package at.aydin.lab.rest.modern;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class RestModernApplication {
    public static void main(String[] args) {
        SpringApplication.run(RestModernApplication.class, args);
    }
}