java - 为什么不 hibernate 从二级缓存加载持久化实体？

休眠是否将保存到使用save方法保存的二级缓存实体中？

我的代码是：

Session session = sessionFactory.openSession();

        Transaction transaction = session.beginTransaction();

        Person person = new Person("Volodia", "Levytskyi", "Mykolaiv");
        session.save(person);
        transaction.commit();
        session.close();

        session = sessionFactory.openSession();
        transaction = session.beginTransaction();

        Person load = (Person) session.load(Person.class, (long) 1);
        System.out.println("load2=" + load);
        transaction.commit();
        session.close();

我希望休眠从第二级缓存人员加载，但是在以下情况下它会向数据库发出选择查询

session.load(Person.class, (long) 1);

在跑。

我的hibernate.cfg.xml：

<session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernateSimpleDB</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password"></property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <property name="transaction.factory_class">org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory</property>

        <property name="hibernate.hbm2ddl.auto">create</property>

        <property name="hibernate.cache.use_second_level_cache">true</property>

        <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
        <property name="hibernate.generate_statistics">true</property>

        <property name="current_session_context_class">thread</property>

        <mapping resource="com/masterhibernate/SimpleHibernateDemo/Person.hbm.xml"
            />

        <!-- <mapping class="com.masterhibernate.SimpleHibernateDemo.Person" /> -->
    </session-factory>
</hibernate-configuration>

我的Person.hbm.xml：

<hibernate-mapping>
    <class name="com.masterhibernate.SimpleHibernateDemo.Person"
        table="Person">
        <cache usage="read-write" />

        <id name="id" column="PersonId">
            <generator class="native" />
        </id>
        <property name="name">
            <column name="name" length="16" not-null="true" />
        </property>
        <property name="surname">
            <column name="surname" length="36"></column>
        </property>
        <property name="address">
            <column name="address" length="22"></column>
        </property>
    </class>
</hibernate-mapping>

为什么是这样？

最佳答案

好像您已设置数据库来为您生成主键。这意味着，当您保存实体时，它还没有ID，因为它将在以后由数据库分配。这也意味着休眠无法将其存储在二级缓存中，因为它尚无用于对其进行索引的键。但是，应再次从数据库中检索它后，将其存储在二级缓存中。