Customer customer = entityManager.find(Customer.class,1);
customer.setLastName("xisss");
System.out.println("sssssssssssssssssssssssss");
//
entityManager.clear();
entityManager.flush();
Customer customer2 = entityManager.find(Customer.class,1);
System.out.println(customer);
System.out.println(customer2);
按理说两个值都是新的才对,但我打印出来 customer是新值,customer2还是老值