UserTransaction tx = null;
        Context ctx;
        try {
            ctx = new InitialContext();
            tx = (UserTransaction)ctx.lookup("javax.transaction.UserTransaction");
            tx.begin();
            // 此处执行DAO中的操作，在DAO的实现中又有上面提到的hibernate事务处理。
              someDao.createSome(someModel);
            someModel.setValue(newValue);
            someDao.updateSome(someModel);
            tx.commit();
        } catch (NamingException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (NotSupportedException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (SystemException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (SecurityException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (IllegalStateException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (RollbackException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (HeuristicMixedException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        } catch (HeuristicRollbackException e) {
            e.printStackTrace();
            rollbackTransaction(tx);
        }

// 这里把回滚的操作抽成方法了，要不代码更多。
    private void rollbackTransaction(UserTransaction tx) {
        if(tx != null){
            try {
                tx.rollback();
            } catch (IllegalStateException e1) {
                e1.printStackTrace();
            } catch (SecurityException e1) {
                e1.printStackTrace();
            } catch (SystemException e1) {
                e1.printStackTrace();
            }
        }
    }