Some examples of the criteria API (JPA 2.0)

When I wrote my examples on how to use JavaFX and JPA 2.0 (part II and III), I made some other tries using Criteria API.

Of course, these examples use the table and the entity described in "Examples using JPA 2.0"

Example using like and a JPA parameter

In JPQL

String param = "Arc%";

        Query query = em.createQuery(
             "select m from Music m where m.artisteName like :param");
        query.setParameter("param", param);
        List<Music> musics = query.getResultList();

        for (Music music : musics){
            System.out.println(music);
        }

Equivalent with Criteria API

String param = "Arc%";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Music> query = cb.createQuery(Music.class);

        Root<Music> music3 = query.from(Music.class);
        query.where(cb.like(music3.<String>get("artisteName"),
                            cb.parameter(String.class, "param")));

        TypedQuery<Music> tq = em.createQuery(query);
        tq.setParameter("param", param);
        List<Music> musics = tq.getResultList();

        for (Music music : musics){
            System.out.println(music);
        }

Example of criteria API using count

In JPQL

String param = "Archive";

        Query query = em.createQuery(
             "select count(m) from Music m where m.artisteName = :artisteNameParam");
        query.setParameter("artisteNameParam", param);
        Long count1 = (Long)query.getSingleResult();

        System.out.println("count : "+count1);

Equivalent with Criteria API

String param = "Archive";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Long> query = cb.createQuery(Long.class);

        Root<Music> music = query.from(Music.class);
        query.select(cb.count(music));
        query.where(cb.equal(music.<String>get("artisteName"),
                             cb.parameter(String.class,"artisteNameParam")));

        TypedQuery<Long> tq = em.createQuery(query);
        tq.setParameter("artisteNameParam", param);

        Long count = tq.getSingleResult();

        System.out.println("count : "+count);

Example of criteria using distinct

In JPQL

String param = "Arc%";

        Query query = em.createQuery(
             "select distinct m.artisteName from Music m where m.artisteName like :param");
        query.setParameter("param", param);
        List<String> artistes= query.getResultList();

        for (String artiste : artistes){
            System.out.println(artiste);
        }

Equivalent with Criteria API

String param = "Arc%";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<String> query = cb.createQuery(String.class);

        Root<Music> music = query.from(Music.class);
        query.select(music.<String>get("artisteName"));
        query.distinct(true);

        query.where(cb.like(music.<String>get("artisteName"),
                            cb.parameter(String.class, "param")));

        TypedQuery<String> tq = em.createQuery(query);
        tq.setParameter("param", param);

        List<String> artistes = tq.getResultList();


        for (String artiste : artistes){
            System.out.println(artiste);
        }

2 articles intéressants sur Sun Developper Network

Le premier, Using the Persistence API in Desktop Applications, explique comment utiliser JPA dans une application Desktop en utilisant TopLink Essentials comme implémentation JPA Et le second, Java Web Start Technology and Application Clients in the GlassFish Application Server, montre comment faire une application riche en utilisant ACC (Application Client Container) de JEE et Java Web Start avec le serveur d’application GlassFish de Sun.