Java 冬眠+；简单示例中的ehcache二级缓存未命中

我使用hibernate统计信息来收集关于2级缓存未命中或命中的信息。 为什么在执行测试模块时，只有二级未命中，而没有命中？ 为什么在我的示例中二级缓存不起作用

我有下一个hibernate.cfg.xml：

    <?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.100.0:1521:rrr</property>
        <property name="hibernate.connection.username">ora</property>
        <property name="hibernate.connection.password">lll</property>
        <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
        <property name="hibernate.default_schema">ora</property>
        <property name="hibernate.current_session_context_class">thread</property>
        <property name="hibernate.generate_statistics">true</property>
        <property name="show_sql">false</property>
        <property name="format_sql">false</property>
        <property name="use_sql_comments">false</property>

        <property name="hibernate.cache.use_second_level_cache">true</property>
        <property name="hibernate.cache.use_query_cache">true</property>
        <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
        <property name="net.sf.ehcache.configurationResourceName">/ehcache.xml</property>


        <mapping class="com.ric.bill.model.bs.Lst"></mapping>
        <mapping class="com.ric.bill.model.bs.LstTp"></mapping>

    </session-factory>
</hibernate-configuration>

我的测试模块：

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SessionFactory sf = HibernateUtil.getSessionFactory();
        Session sess = sf.openSession();
        sess.beginTransaction();

        for (int a=1401; a<=1452; a++) {
            Lst lst = (Lst) sess.load(Lst.class, a);
            System.out.println(lst.getName());
        }
        for (int a=1401; a<=1452; a++) {
            Lst lst = (Lst) sess.load(Lst.class, a);
            System.out.println(lst.getName());
        }
        Statistics stats = sf.getStatistics();
        printStats(stats, 0);

        sess.getTransaction().commit();

        System.out.println("Complete!");

    }
}

---

二级缓存用于在不同会话之间缓存实体。在这里，您处于同一会话中，因此hibernate不必转到2级缓存：它可以从会话中获取实体

正如你所看到的，你只有52次失误，而不是104次。只有第一个for循环生成这些未命中。然后hibernate获取实体，将它们放在会话和二级缓存中。在第二个循环中，它在会话中找到它们，并且不必查看二级缓存，因此不会生成命中或未命中

---

要测试2级缓存，请在第一个for循环结束时关闭事务和会话，并在第二个for循环之前打开新的事务和会话。

真的！我关闭了第一个会话并打开了另一个会话，它现在可以工作了：获取计数=52第二级命中计数=52第二级未命中计数=52第二级放置计数=52完成！是的，这是第二级缓存的使用。注意：现在您的实体在线程之间共享。

 <project xmlns="http://maven.apache.org/POM/4.0.0"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0   http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.journaldev.hibernate</groupId>
<artifactId>HibernateEHCacheExample</artifactId>
<version>0.0.1-SNAPSHOT</version>
<description>Hibernate Secondary Level Cache Example using EHCache implementation</description>

<dependencies>
    <!-- Hibernate Core API -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.1.0.Final</version>
    </dependency>
    <!-- EHCache Core APIs -->
    <!-- http://mvnrepository.com/artifact/net.sf.ehcache/ehcache-core -->
    <dependency>
        <groupId>net.sf.ehcache</groupId>
        <artifactId>ehcache-core</artifactId>
        <version>2.6.11</version>
    </dependency>

    <!-- http://mvnrepository.com/artifact/org.hibernate/hibernate-ehcache -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-ehcache</artifactId>
        <version>5.2.0.Final</version>
    </dependency>

    <!-- EHCache uses slf4j for logging -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.5</version>
    </dependency>
</dependencies>
</project>

package com.ric.bill.model.bs;

import javax.persistence.Cacheable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;

import com.ric.bill.Simple;

@SuppressWarnings("serial")
@Entity
@Table(name = "LIST", schema="BS")
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE, region="billCache")
@Cacheable
public class Lst implements java.io.Serializable, Simple {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "ID", updatable = false, nullable = false)
    private Integer id; //id

    @Column(name = "CD", updatable = false, nullable = false)
    private String cd; //cd 

    @Column(name = "NAME", updatable = false, nullable = false)
    private String name; //Наименование 

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="FK_LISTTP", referencedColumnName="ID")
    private LstTp lstTp ; 


    public Integer getId() {
        return this.id;
    }
    public void setId(Integer id) {
        this.id = id;
    }

    public String getCd() {
        return this.cd;
    }
    public void setCd(String cd) {
        this.cd = cd;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public LstTp getLstTp() {
        return lstTp;
    }
    public void setLstTp(LstTp lstTp) {
        this.lstTp = lstTp;
    }

}

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SessionFactory sf = HibernateUtil.getSessionFactory();
        Session sess = sf.openSession();
        sess.beginTransaction();

        for (int a=1401; a<=1452; a++) {
            Lst lst = (Lst) sess.load(Lst.class, a);
            System.out.println(lst.getName());
        }
        for (int a=1401; a<=1452; a++) {
            Lst lst = (Lst) sess.load(Lst.class, a);
            System.out.println(lst.getName());
        }
        Statistics stats = sf.getStatistics();
        printStats(stats, 0);

        sess.getTransaction().commit();

        System.out.println("Complete!");

    }
}

 Fetch Count=52
 Second Level Hit Count=0
 Second Level Miss Count=52
 Second Level Put Count=52
 Complete!