java - EJB3 CMP + Hibernate AnnotationConfiguration 的编程配置

Question

我使用 EJB3 容器管理的持久性，即通过 @PersistenceContext 注释注入(inject) EntityManager。然后，持久上下文可以传播到嵌套 EJB。交易也由容器(glassfish)管理。

通常我会将 persistence.xml 放入 META-INF 目录中，容器将确定要使用哪个提供程序以及如何配置 EntityManagerFactory(基于 hibernate 特定属性)。

我的问题是我需要 Hook EntityManagerFactory 配置过程。 特别是，我需要在 EntityManagerFactory 配置之前更改某些 PersistentClasses 中的鉴别器值(任何更改都会卡住)。

这就是我使用 Spring 执行此操作的方法，但需要使用纯 EJB3 CMP 执行类似操作(或者可能在 Spring 的帮助下)。

public class AnnotationSessionFactoryBean extends  org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean {
    /** Log4j logging instance. */
    protected static Logger log = Logger.getLogger(AnnotationSessionFactoryBean.class);

    //some data preloaded from the database using jdbc
    private Map<String, DatabaseConfiguration> configs;

    @Override
    protected void postProcessAnnotationConfiguration(AnnotationConfiguration config) throws HibernateException {
        //Load and process dynamic Mappings.
        Iterator classMappingsIter = config.getClassMappings();
        while(classMappingsIter.hasNext()) {
            PersistentClass persistentClass = (PersistentClass) classMappingsIter.next();

            String discriminatorValue = persistentClass.getDiscriminatorValue();
            if(discriminatorValue != null) {
                log.debug("DiscriminatorValue before [" + discriminatorValue + "]");
                //here I replace discriminator values.
                //The Discriminator values are coded in the annotations
                //as names (words). These words need to be replaced with ids
                //previously loaded from the database using jdbc.
                //The names are constant in all environments, however the ids are
                //are different.    
                discriminatorValue = StringUtil.replacePlaceholders(discriminatorValue, configs);
                persistentClass.setDiscriminatorValue(discriminatorValue);
                log.debug("DiscriminatorValue after [" + discriminatorValue + "]");
            }


        }
        super.postProcessAnnotationConfiguration(config);
    }

    /**
     * @return the configs
     */
    public Map<String, DatabaseConfiguration> getConfigs() {
        return configs;
    }

    /**
     * @param configs the configs to set
     */
    public void setConfigs(Map<String, DatabaseConfiguration> configs) {
        this.configs = configs;
    }


}

提前致谢， 安东

Answer 1

我想我已经找到了解决方案。 org.hibernate.ejb.HibernatePersistence 类可以被覆盖。

public class HibernatePersistenceCustom extends org.hibernate.ejb.HibernatePersistence {
    /** Log4j logging instance. */
    protected static Logger log = Logger.getLogger(HibernatePersistenceCustom.class);

    @Override
    public EntityManagerFactory createContainerEntityManagerFactory(PersistenceUnitInfo info, Map map) {
        Ejb3Configuration cfg = new Ejb3Configuration();
        //here you can configure it
        doCustomConfiguration(cfg);
        Ejb3Configuration configured = cfg.configure(info, map);
        return configured != null ? configured.buildEntityManagerFactory() : null;
    }

    ...
    //other methods can also be overridden if required.


    public void doCustomConfiguration(Ejb3Configuration config) {
        //Load and process dynamic Mappings.
        Iterator classMappingsIter = config.getClassMappings();
        while(classMappingsIter.hasNext()) {
            PersistentClass persistentClass = (PersistentClass) classMappingsIter.next();

            String discriminatorValue = persistentClass.getDiscriminatorValue();
            if(discriminatorValue != null) {
                log.debug("DiscriminatorValue before [" + discriminatorValue + "]");
                //here I replace discriminator values.
                //The Discriminator values are coded in the annotations
                //as names (words). These words need to be replaced with ids
                //previously loaded from the database using jdbc.
                //The names are constant in all environments, however the ids are
                //are different.    
                discriminatorValue = StringUtil.replacePlaceholders(discriminatorValue, configs);
                persistentClass.setDiscriminatorValue(discriminatorValue);
                log.debug("DiscriminatorValue after [" + discriminatorValue + "]");
            }


        }

    } 
}

然后在 persistence.xml 而不是 org.hibernate.ejb.HibernatePersistence 中放入 com.mydomain.persistence.HibernatePersistenceCustom

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" 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_1_0.xsd">
  <persistence-unit name="mypersistenceunit" transaction-type="JTA">
    <provider>com.mydomain.persistence.HibernatePersistenceCustom</provider>
    <jta-data-source>jdbc/mydatasource</jta-data-source>
    <properties>
      <property name="hibernate.show_sql" value="false"/>
      <property name="hibernate.format_sql" value="false"/>
      <property name="hibernate.use_sql_comments" value="false"/>
      <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.SunONETransactionManagerLookup"/>
      <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
    </properties>
  </persistence-unit>
</persistence>

尚未测试，但我认为它会起作用。

谢谢