为什么80%的码农都做不了架构师？>>> 
JPA 2.1: Bulk Update and Delete
In the JPA 2.0 and early version, if you want to execute a bulk updating query, you have to use update or delete clause in JPQL directly. JPA 2.1 introduce new Criteria API for updating and deleting.
Post entity
Reuse the Post entity class as example. Add an extra boolean approved property.
In this example, the bulk update operation will set the approved value to true.
<pre> @Entity @Table(name="POSTS") public class Post implements Serializable { private boolean approved = false; } </pre>
Criteria Update and Delete API
In JPA 2.1, new CriteriaUpdate and CriteriaDelete are introduced in Criteria API for updating and deleting. The usage is very simple.
The CriteriaUpdate example.
<pre> CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaUpdate<Post> q = cb.createCriteriaUpdate(Post.class); Root<Post> root = q.from(Post.class); q.set(root.get("approved"), true) .where(root.get("id").in(getCheckedList())); int result = em.createQuery(q).executeUpdate(); log.info("update @" + result); </pre>
The CriteriaDelete example.
<pre> CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaDelete<Post> q = cb.createCriteriaDelete(Post.class); Root<Post> root = q.from(Post.class); q.where(root.get("id").in(checkedList)); int result = em.createQuery(q).executeUpdate(); log.info("delete @" + result); </pre>
The checkedList value is from checkbox values from JSF UI.
Summary
This feature is a small improvement to JPA API. If you are stick on the type-safe JPA metadata API for JPA programming, it is a big step.
The sample codes are hosted on my github.com account, check out and play it yourself.
https://github.com/hantsy/ee7-sandbox
When you run the project(jpa-bulk) on Glassfish 4.0 and you could get an exception.
<pre> java.lang.RuntimeException: unable to create policy context directory. </pre>
There is a known issue in Glassfish 4.0, the fix should be included in the next release. I am using a Nightly version to overcome this barrier temporarily.
