Question

我刚刚浏览了this article和this，我发现它会提高应用程序的性能，因为它只有99％的读取操作。我首先在测试应用程序中实现它只是为了测试它（引用this），虽然我得到了结果但是根据我提到的第二个链接，如果查询对于相同参数是相同的值，db命中率将基于主键的关系。

课程如下：

实体类

@Entity(name="User_Details")
public class UserDetails {
    @Id
    private String userName;
    private String password;
    private String  name;
    private Long msisdn;
   //getter and setter are in place//
}

DAO课程

public class UserDetailsDAOImpl {

SessionFactory sessionFactory;

public UserDetailsDAOImpl() {
    sessionFactory = new Configuration().configure().buildSessionFactory();
}

public UserDetails getUser(String param1) {
    Session session = sessionFactory.openSession();
    System.out.println("session : " + session);     
    session.beginTransaction();        
    Criteria query =  session.createCriteria(UserDetails.class).add(Restrictions.eq("name",param1));
    UserDetails dummy_user=(UserDetails) query.setCacheable(true).uniqueResult();
    session.close();
    return dummy_user;
}

主要类

    UserDetailsDAOImpl obj=new UserDetailsDAOImpl();        
    UserDetails response = obj.getUser("Borat16");  
    System.out.println("Test:"+response);   
    UserDetails response1 = obj.getUser("Borat16"); 
    System.out.println("Test1:"+response1);

hibernate.cfg.xml中

    <property name="hibernate.cache.use_second_level_cache">true</property>
    <!--<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>-->
     <property name = "hibernate.cache.use_query_cache">org.hibernate.cache.EhCacheProvider</property>
    <property name="show_sql">true</property>
    <property name="hbm2ddl.auto">update</property>

// 第一个查询结果：根据文章的第一次，它会点击db（如预期的那样）

Hibernate: select this_.userName as userName1_0_0_, this_.msisdn as msisdn2_0_0_, this_.name as name3_0_0_, this_.password as password4_0_0_ from User_Details this_ where this_.name=?
Test:UserDetails [userName=ak416, password=magnum16, name=Borat16, msisdn=116]

// 第二个查询结果：现在由于查询相同且相同的参数，为什么生成的sql语句看起来不像“select * from user_details where userName ='ak47'。我的意思是它应该使用以参数为键命中数据库。我缺少什么？！

Hibernate: select this_.userName as userName1_0_0_, this_.msisdn as msisdn2_0_0_, this_.name as name3_0_0_, this_.password as password4_0_0_ from User_Details this_ where this_.name=?
Test1:UserDetails [userName=ak416, password=magnum16, name=Borat16, msisdn=116]

Answer 1

您正在使用

<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

因此您的缓存未启用（ NoCacheProvider ）

Answer 2

一旦设置了cache_provider值，请确保将以下值设置为＆＃34; true＆＃34;启用查询级缓存。

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

Hibernate查询缓存，行为不符合预期

2 个答案: