JPA Enhancer Prototype

gistfile1.txt

public class Order {

	private long id;
	private Set<Product> products;

	public Order(long id) {
		this.id = id;
	}

	public long getId() {
		return id;
	}

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

	public Set<Product> getProducts() {
		if (products == null) {
			products = new LinkedHashSet<>();
		}
		return new OneToMany1(this, products);
	}

	public void setProducts(Set<Product> products) {
		final Set<Product> oldProducts = this.products;
		this.products = products;

		if (oldProducts != null) {
			if (products == null) {
				oldProducts.clear();
			} else {
				new OneToMany1(this, oldProducts).retainAll(products);
			}
		}
		if (products != null) {
			for (final Product e : products) {
				if (e.getOrder() != this) {
					e.setOrder(this);
				}
			}
		}
	}

	@Override
	public int hashCode() {
		int hash = 7;
		hash = 89 * hash + (int) (this.id ^ (this.id >>> 32));
		return hash;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null) {
			return false;
		}
		if (getClass() != obj.getClass()) {
			return false;
		}
		final Order other = (Order) obj;
		if (this.id != other.id) {
			return false;
		}
		return true;
	}

	@Override
	public String toString() {
		return "Order{" + "id=" + id + '}';
	}
}

class Product {

	private long id;
	private Order order;

	public Product(long id) {
		this.id = id;
	}

	public long getId() {
		return id;
	}

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

	public Order getOrder() {
		return order;
	}

	public void setOrder(Order newOrder) {
		final Order oldOrder = this.order;
		this.order = newOrder;

		if (oldOrder != null) {
			oldOrder.getProducts().remove(this);
		}
		if (newOrder != null) {
			newOrder.getProducts().add(this);
		}
		System.out.println("product.order changed from: " + oldOrder + " to: " + newOrder);
	}

	@Override
	public int hashCode() {
		int hash = 5;
		hash = 79 * hash + (int) (this.id ^ (this.id >>> 32));
		return hash;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null) {
			return false;
		}
		if (getClass() != obj.getClass()) {
			return false;
		}
		final Product other = (Product) obj;
		if (this.id != other.id) {
			return false;
		}
		return true;
	}

	@Override
	public String toString() {
		return "Product{" + "id=" + id + '}';
	}
}

class OneToMany1 implements Set<Product> {

	private final Order owner;
	private final Set<Product> storage;

	public OneToMany1(Order owner, Set<Product> storage) {
		this.owner = owner;
		this.storage = storage;
	}

	@Override
	public Iterator<Product> iterator() {
		return storage.iterator();
	}

	@Override
	public int size() {
		return storage.size();
	}

	@Override
	public boolean isEmpty() {
		return storage.isEmpty();
	}

	@Override
	public boolean contains(Object o) {
		return storage.contains(o);
	}

	@Override
	public boolean add(Product e) {
		final boolean ret = storage.add(e);
		if (e.getOrder() == owner) {
			return ret;
		} else if (e.getOrder() == null) {
			e.setOrder(owner);
			return ret;
		} else {
			e.getOrder().getProducts().remove(e);
			return ret;
		}
	}

	@Override
	public boolean remove(Object o) {
		final Product e = (Product) o;
		final boolean ret = storage.remove(e);

		if (e.getOrder() == owner) {
			e.setOrder(null);
		}

		return ret;
	}

	@Override
	public void clear() {
		final List<Product> oldEntries = new ArrayList<>(storage);
		storage.clear();
		for (final Product e : oldEntries) {
			if (e.getOrder() == owner) {
				e.setOrder(null);
			}
		}
	}

	@Override
	public boolean equals(Object o) {
		return storage.equals(o);
	}

	@Override
	public int hashCode() {
		return storage.hashCode();
	}

	@Override
	public boolean removeAll(Collection<?> c) {
		boolean ret = false;
		for (final Object e : c) {
			if (remove((Product) e)) {
				ret = true;
			}
		}
		return ret;
	}

	@Override
	public Object[] toArray() {
		return storage.toArray();
	}

	@Override
	public <T> T[] toArray(T[] a) {
		return storage.toArray(a);
	}

	@Override
	public boolean containsAll(Collection<?> c) {
		return storage.containsAll(c);
	}

	@Override
	public boolean addAll(Collection<? extends Product> c) {
		return storage.addAll(c);
	}

	@Override
	public boolean retainAll(Collection<?> c) {
		boolean ret = false;
		final LinkedHashSet<Product> removed = new LinkedHashSet<>(c.size());
		for (final Product e : storage) {
			if (!c.contains(e)) {
				removed.add(e);
			}
		}
		
		for (final Product e : removed) {
			if (remove(e)) {
				ret = true;
			}
		}
		return ret;
	}

	@Override
	public String toString() {
		return storage.toString();
	}
}