Fix EntityManager injection in DAO implementation

Benjamin Rühl
1 parent 78b1332d
Showing 3 changed files with 45 additions and 60 deletions
services/Global/src/main/java/de/bht/beuthbot/daos/AppUserDAO.java
services/Global/src/main/java/de/bht/beuthbot/daos/GenericHibernateDAO.java
services/Global/src/main/resources/META-INF/persistence.xml
@@ -10,11 +10,7 @@ import javax.ejb.Stateless;
  * Created by Benjamin Rühl on 19.12.2017.
  */
 @Stateless
-public class AppUserDAO extends GenericHibernateDAO<User, Long> implements UserDAO {
-
-    public AppUserDAO() {
-        setEntityClass(AppUser.class);
-    }
+public class AppUserDAO extends GenericHibernateDAO<User, AppUser, Long> implements UserDAO {
  
     @Override
     public User createUser() {
@@ -2,102 +2,91 @@ package de.bht.beuthbot.daos;
  
 import de.bht.beuthbot.dataAccess.GenericDAO;
 import de.bht.beuthbot.model.entities.Entity;
-import org.hibernate.Criteria;
 import org.hibernate.Session;
-import org.hibernate.criterion.Criterion;
  
+import javax.annotation.PostConstruct;
 import javax.ejb.Stateless;
-import javax.enterprise.inject.InjectionException;
 import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
 import javax.persistence.PersistenceContext;
 import javax.persistence.PersistenceUnit;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.Root;
 import java.io.Serializable;
 import java.lang.reflect.ParameterizedType;
 import java.util.List;
  
 /**
  * Created by Benjamin Rühl on 19.12.2017.
+ * Base class for DAO implementations using hibernate for persistence.
+ * Provides generic functionality for interaction with entities.
+ * @param <I>  Interface type of entity class
+ * @param <T>  Implementation type of entity class
+ * @param <ID> Type of entity's primary id
  */
 @Stateless
-public class GenericHibernateDAO<T extends Entity, ID extends Serializable> implements GenericDAO<T, ID> {
+public class GenericHibernateDAO<I extends Entity, T extends I, ID extends Serializable> implements GenericDAO<I, ID> {
  
-    private Class<? extends T> entityClass;
-    private Session session;
+    private Class<T> entityClass;
  
-    @PersistenceUnit(unitName = "PostgreSQLDS")
-    private EntityManagerFactory emf;
+    @PersistenceUnit(unitName = "PostgresPU")
+    private EntityManagerFactory entityManagerFactory;
  
-    @PersistenceContext(unitName = "PostgreSQLDS")
-    private EntityManager em;
+    @PersistenceContext(unitName = "PostgresPU")
+    private EntityManager entityManager;
  
     @SuppressWarnings("unchecked cast")
-    public GenericHibernateDAO() {
-        if (em == null)
+    @PostConstruct
+    public void init() {
+        if (entityManager == null)
             throw new RuntimeException("EntityManager must not be null");
  
-        entityClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
-        setSession( (Session)em.getDelegate() );
+        entityClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[1];
     }
  
-    public void setSession(Session s) {
-        this.session = s;
-    }
-
-    protected Session getSession() {
-        if (session == null)
-            throw new IllegalStateException("Session has not been set on DAO before usage");
-        return session;
-    }
-
-    /**
-     * Use this in subclasses to set entityClass to derived type of T
-     */
-    protected void setEntityClass(Class<? extends T> entityClass) {
-        this.entityClass = entityClass;
-    }
-
-    public Class<? extends T> getEntityClass() {
+    public Class<T> getEntityClass() {
         return entityClass;
     }
  
     @Override
-    public T findById(ID id) {
-        return getSession().load(getEntityClass(), id);
+    public I findById(ID id) {
+        return entityManager.find(getEntityClass(), id);
     }
  
-    public List<T> findAll() {
+    @Override
+    public List<I> findAll() {
         return findByCriteria();
     }
  
     @Override
-    public T saveOrUpdate(T entity) {
-        getSession().saveOrUpdate(entity);
+    public I saveOrUpdate(I entity) {
+        entityManager.merge(entity);
         return entity;
     }
  
     @Override
-    public void delete(T entity) {
-        getSession().delete(entity);
-    }
-
-    public void flush() {
-        getSession().flush();
-    }
-
-    public void clear() {
-        getSession().clear();
+    public void delete(I entity) {
+        entityManager.remove(entity);
     }
  
     /**
      * Use this inside subclasses as a convenience method.
      */
-    @SuppressWarnings("unchecked")
-    protected List<T> findByCriteria(Criterion... criterion) {
-        Criteria crit = getSession().createCriteria(getEntityClass());
-        for (Criterion c : criterion) {
-            crit.add(c);
-        }
-        return crit.list();
+    protected List<I> findByCriteria(Predicate... restrictions) {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<T> criteria = builder.createQuery(getEntityClass());
+        Root<T> criteriaRoot = criteria.from(getEntityClass());
+
+        criteria.select(criteriaRoot);
+        criteria.where(restrictions);
+
+        List<T> elements = entityManager.createQuery(criteria).getResultList();
+        return (List<I>) elements;
+    }
+
+    protected EntityManager getEntityManager() {
+        return entityManager;
     }
 }
@@ -4,7 +4,7 @@
              http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
              version="2.1">
  
-    <persistence-unit name="PostgreSQLDS" transaction-type="JTA">
+    <persistence-unit name="PostgresPU" transaction-type="JTA">
  
         <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>