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@asicfr
Created October 15, 2012 08:51
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struts2RestJpaBootstrap - dao generic
package org.demo.util;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.persistence.TypedQuery;
public abstract class GenericJpaDao<T, PK extends java.io.Serializable> {
private final Class<T> persistentClass;
/**
* @param persistentClass
*/
public GenericJpaDao(final Class<T> persistentClass) {
this.persistentClass = persistentClass;
}
/**
* @param <T>
* @param id
* @return
*/
public <T> T findById(PK id) {
final EntityManager em = getEntityManager();
return (T) em.find(this.persistentClass, id);
}
/**
* @param queryName
* @param queryParams
* @return
*/
public List<T> findByNamedQuery(String queryName, Map<String, Object> queryParams) {
final EntityManager em = getEntityManager();
final Query query = em.createNamedQuery(queryName);
final Iterator<String> i = queryParams.keySet().iterator();
while (i.hasNext()) {
String key = i.next();
query.setParameter(key, queryParams.get(key));
}
return query.getResultList();
}
/**
* @param <T>
* @param query
* @return
*/
public <T> Collection<T> loadList(String query) {
final EntityManager em = getEntityManager();
final TypedQuery q = em.createQuery(query, this.persistentClass);
return q.getResultList();
}
/**
* @param <T>
* @param query
* @return
*/
public <T> List<T> loadAll() {
final EntityManager em = getEntityManager();
final Query query = em.createQuery("from " + persistentClass.getName());
return query.getResultList();
}
/**
* @param <T>
* @return
*/
public <T> T insert(T entity) {
final EntityManager em = getEntityManager();
em.persist(entity);
return (entity);
}
/**
* @param <T>
* @param entity
* @return
*/
public <T> T update(T entity) {
final EntityManager em = getEntityManager();
entity = em.merge(entity);
return entity;
}
/**
* @param pk
*/
public void delete(PK pk) {
final EntityManager em = getEntityManager();
final T entity = em.find(this.persistentClass, pk);
if (entity != null) {
em.remove(entity);
}
}
/**
* @param entity
*/
public void delete(T entity) {
final EntityManager em = getEntityManager();
if (entity != null) {
em.refresh(entity);
em.remove(entity);
}
}
// ***************************************************************************************
protected EntityManager getEntityManager() {
return EntityManagerHelper.getEntityManager();
}
}
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