openjpa范例及实例工程

package cn.com.shxt.openjpa.util; import java.util.Properties; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; public class BaseEntityManager { private static final Properties jpaProperties = new Properties(); private static final String DEFAULT_DATABASE = "Polling"; private static EntityManagerFactory entityManagerFactory = null; private static EntityManager entityManager = null; public static Properties getJPAProperties() { return jpaProperties; } public static EntityManagerFactory getEntityManagerFactory() { entityManagerFactory = Persistence.createEntityManagerFactory( DEFAULT_DATABASE, jpaProperties); return entityManagerFactory; } public static EntityManager getEntityManager() { if (entityManagerFactory == null) { entityManagerFactory = getEntityManagerFactory(); } entityManager = entityManagerFactory.createEntityManager(); return entityManager; } public static EntityTransaction getTransaction() { if (entityManager == null) { entityManager = getEntityManager(); } return entityManager.getTransaction(); } public static void close() { if (entityManager != null) { entityManager.close(); } if (entityManagerFactory != null) { entityManagerFactory.close(); } } }