[JavaEngineer]

#java
#j2ee

W jaki sposób oznaczacie DAO ?

package dao;

import model.BaseEntity;

import javax.ejb.Stateless;
import javax.ejb.TransactionAttribute;
import javax.ejb.TransactionAttributeType;
import javax.inject.Named;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.List;

@Stateless
@Named("baseDao")
public class BaseDao, ID> implements Serializable {

 @PersistenceContext
 private EntityManager entityManager;
 private Class entityClass;

 public EntityManager getEntityManager() {
 return entityManager;
 }

 public void setEntityManager(EntityManager entityManager) {
 this.entityManager = entityManager;
 }

 public Class getEntityClass() {
 if (entityClass == null) {
 //only works if one extends BaseDao, we will take care of it with CDI
 entityClass = (Class) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
 }
 return entityClass;
 }

 public void setEntityClass(Class entityClass) {
 this.entityClass = entityClass;
 }

 //utility database methods
 @TransactionAttribute(TransactionAttributeType.SUPPORTS)
 public T find(ID id) {
 return (T) this.entityManager.find(getEntityClass(), id);
 }

 public void delete(ID id) {
 Object ref = this.entityManager.getReference(getEntityClass(), id);
 this.entityManager.remove(ref);
 }

 public T update(T t) {
 return (T) this.entityManager.merge(t);
 }

 public void insert(T t) {
 this.entityManager.persist(t);
 }

 @TransactionAttribute(TransactionAttributeType.SUPPORTS)
 public List findAll() {
 return entityManager.createQuery("Select entity FROM " + getEntityClass().getSimpleName() + " entity").getResultList();
 }
}