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我有一个最小的网络应用程序,你可以在这里下载(6Kb): http ://www.mediafire.com/?6vo1tc141t65r1g

相关配置是:

-eclipselink 2.3.2

-server 是 tomee 1.0(但 glassfish 3.1 是一样的)

当我点击页面并按 F5 重复刷新时:

http://localhost:8080/testCache/jsf/test.xhtml

我在控制台中看到几行这样的行

[EL Fine]: 2012-08-29 19:01:30.821--ServerSession(32981564)--Connection(27242067)--Thread(Thread[http-bio-8080-exec-12,5,main])--从任务类型中选择 ID、任务类型

通过运行嗅探器,我看到 SQL 请求总是发送到服务器。我虽然 Eclipselink 的 2 级缓存会返回结果(表中的 5 行)而不查询数据库。那么怎么了,我该如何激活缓存?

文件中的一些摘录

持久性.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
  <persistence-unit name="xxxPU" transaction-type="JTA">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <jta-data-source>microsoft</jta-data-source>
    <properties>

        <property name="eclipselink.logging.level" value="FINE"/>
      <property name="eclipselink.logging.parameters" value="true"/>

    </properties>
  </persistence-unit>
</persistence>

执行查询的 EJB

/**
 * Some useless class required to use JTA transactions
 * 
 * @author Administrator
 * 
 */
@Stateless
public class Facade {
    @PersistenceContext(unitName = "xxxPU")
    private EntityManager em;


    public List findAll(Class entityClass) {
        CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
        cq.select(cq.from(entityClass));
        return em.createQuery(cq).getResultList();
    }

    public EntityManager getEntityManager() {
        return em;

    }

}

实体bean:

@Entity
@Table(name = "tasktype")

public class TaskType {

    @Id

    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 10)
    @Column(name = "tasktype")
    private String name;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

}
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1 回答 1

5

L2 共享缓存,通过那里的 Id 缓存对象。find() 操作和 Id 查询将获得缓存命中,其他查询不会。生成的对象仍将通过缓存进行解析,因此一旦对象被缓存,您将不会对关系进行任何额外的查询。

您可以在查询上启用缓存,或者(在 2.4 中)您可以索引非 Id 字段,或在内存中查询。

见, http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Caching

http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Caching/Query_Cache

http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Caching/Query_Options

于 2012-08-29T12:35:42.150 回答