hibernate API在業務層的封裝和使用

 為了建立，初始化，和調用全域的sessionFactory執行個體，我們使用HibernateUtil類可以將Hibernate API封裝起來，減少重複代碼的書寫，也使得程式看起來更簡潔明了     package ...     import ...     public class HibernateUtil {     private static Log log = LogFactory.getLog(HibernateUtil.class);     private static Configuration configuration;     private static SessionFactory sessionFactory;       static {        try {          configuration = new Configuration();          sessiongFactory = configuration.().configure().buildSessionFactory();       } catch(Throwable ex) {          log.error(ex.getMessage());          throw new ExceptionInInitializeError(ex);       }     }       public static SessionFactory getSessionFactory() {        return sessionFactory;     }       public static Configuration getConfiguration() {        return configuration;     }       public static void rebuildSessionFactory() {        Synchronized(sessiongFactory) {           try{              sessionfFactory=getConfiguration().buildSessionFactory();           } catch(Exception ex) {              log.error(ex.getMessage());              throw DatastoreException.datastoreError(ex);           }       }     }       public static void rebuildSessionFactory(Configuration cfg) {        Synchronized(sessiongFactory) {           try{              sessionfFactory= cfg.buildSessionFactory();              configuration = cfg;           } catch(Exception ex) {              log.error(ex.getMessage());              throw DatastoreException.datastoreError(ex);           }       }     }       public static void close(){        try{            sessionFactory.close();        } catch(Exception ex) {            log.error(ex.getMessage());        }     }       //下面是程式中最常用的session的開啟，關閉和復原     public static Session getSession() throws DatastoreException{        try {            return sessionFactory.openSession();        }catch(Exception ex) {            log.error(ex.getMessage());            throw DatastoreException.datastoreError(ex);        }     }       public static void closeSession(Session session) throws DatastoreException {         try{            session.close();         } catch(Exception ex){            log.error(ex.getMessage());            throw DatastoreException.datastoreError(ex);         }     }       public static void rollbackTransaction(Transaction transaction) throws DatastoreException {          try{            if(transaction != null)              transaction.rollback();          } catch(Exception ex){              log.error(ex.getMessage());              throw DatastoreException.datastoreError(ex);          }     } }     封裝後的使用的例子：     Session session = HibernateUtil.getSession();     Transaction tx = null;     try {       tx = session.beginTransaction();         //hibernate資料庫操作       Query query = session.createQuery...         tx.commit();       } catch(Exception ex) {        HibernateUtil.rollbackTransaction(ex);        throw DatastoreException.datastoreError(ex);     } finally {        HibernateUtil.closeSession(session);     }