example.java

// DAO

public static void save(User user) throws PSQLException {
	EntityManager em = AppEntityManager.getInstance();
	em.getTransaction().begin();
	em.persist(user);
	em.getTransaction().commit();
}

// Controller

public static Result add() {
		
	User user = (User) Json.fromJson(request().body().asJson(), User.class);
	
	try {
		UserDAO.save(user);
	} catch (PSQLException e) {
		return badRequest(Json.toJson(e.getMessage())).as("application/json");
	}
	
	return ok(Json.toJson(user)).as("application/json");	
}