## 查询 ~~~ Customer customer = entityManager.find(Customer.class, 1L); //相当于get() ~~~ ~~~ Customer customer = entityManager.getReference(Customer.class, 1L); //相当于load() ~~~ ## 修改 JPA中也是有一级缓存的. ~~~ Customer customer = entityManager.getReference(Customer.class, 1L); customer.setCust_name("milan"); entityManager.merge(customer); //相当于update() ~~~ ## 删除 ~~~ Customer customer = entityManager.getReference(Customer.class, 1L); customer.setCust_name("milan"); entityManager.remove(customer); //相当于delete() ~~~