Student stu = new Strudnet();stu.setCarId(“200234567”);stu.setId(“100”);// 打开 Session, 开启事务//将stu对象持久化操作
session.save(stu);stu.setCardId(“20076548”);//再次对stu对象进行持久化操作
session.save(stu); // 无效

session.update(stu); // 无效// 提交事务，关闭 Session

    public static void testOneLeveCache(){Session session=HibernateUtil.getSession();//获取持久化对象DeptDept d1=(Dept)session.get(Dept.class, 10);//再次获取持久化对象DeptDept d2=(Dept)session.get(Dept.class, 10);    session.close();}

Hibernate: selectdept0_.DEPTNO as DEPTNO0_0_,dept0_.DNAME as DNAME0_0_,dept0_.LOC as LOC0_0_ fromSCOTT.DEPT dept0_ wheredept0_.DEPTNO=?

    public static void testOneLeveCache(){Session session=HibernateUtil.getSession();SessionFactory sf = HibernateUtil.getSessionFactory();//获取持久化对象DeptDept d1=(Dept)session.get(Dept.class, 10);session.clear();//清除所有缓存session.evict(d1);//清除指定缓存//再次获取持久化对象DeptDept d2=(Dept)session.get(Dept.class, 10);    session.close();}

Hibernate: selectdept0_.DEPTNO as DEPTNO0_0_,dept0_.DNAME as DNAME0_0_,dept0_.LOC as LOC0_0_ fromSCOTT.DEPT dept0_ wheredept0_.DEPTNO=?
Hibernate: selectdept0_.DEPTNO as DEPTNO0_0_,dept0_.DNAME as DNAME0_0_,dept0_.LOC as LOC0_0_ fromSCOTT.DEPT dept0_ wheredept0_.DEPTNO=?

    <!-- 开启二级缓存 --><property name="hibernate.cache.use_second_level_cache">true</property><!-- 为hibernate指定二级缓存的实现类 --><property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>

<class-cache class="entity.PetInfo" usage="read-only" /> //不允许更新缓存中的对象
<class-cache class="entity.PetInfo" usage="read-write" />  //允许更新缓存中的对象

<hibernate-mapping><class name="com.bdqn.entity.Dept" table="DEPT" schema="SCOTT"  ><cache usage="read-only"/>//将这个类放入二级缓存<id name="deptno" type="java.lang.Integer"><column name="DEPTNO" precision="2" scale="0" /><generator class="assigned"></generator></id><property name="dname" type="java.lang.String"><column name="DNAME" length="14" /></property></class>
</hibernate-mapping>

<defaultCachemaxElementsInMemory="10000"eternal="false"timeToIdleSeconds="120"timeToLiveSeconds="120"overflowToDisk="true"/>

sessionFactory.evict(Entity.class);//清除所有Entity

sessionFactory.evict(Entity.class,id);//清除指定Entity
比如：
//用SessionFacotry管理二级缓存

SessionFactory factory=HibernateUtils.getSessionFactory();//evict()把id为1的Student对象从二级缓存中清除.

factory.evict(Student.class, 1);
//evict()清除所有二级缓存.

factory.evict(Student.class); 

<!-- 是否开启查询缓存,true开启查询缓存，false关闭查询缓存 -->
<property name="cache.use_query_cache">true</property>

public static void testQueryCache(){Session session=HibernateUtil.getSession();String hql="from Emp as e";Query query=session.createQuery(hql);query.setCacheable(true);//启用查询缓存（二级缓存）List<Emp> empList=query.list();session.close();
}        

      session = HibernateUtils.getSession(); t = session.beginTransaction(); Query query = session.createQuery("select s.name from Student s"); //启用查询缓存    query.setCacheable(true); List<String> names = query.list(); for (Iterator<String> it = names.iterator(); it.hasNext();) { String name = it.next(); System.out.println(name); } System.out.println("================================"); query = session.createQuery("select s.name from Student s"); //启用查询缓存 query.setCacheable(true); //没有发出查询语句,因为这里使用的查询缓存 names = query.list(); for (Iterator<String> it = names.iterator(); it.hasNext();) { String name = it.next(); System.out.println(name); } t.commit();