如何使用eclipse链接指定动态类加载器

Question

环境： Tomcat Web服务器，eclipselink-2.4.1（Juno）JPA，Odata4j 我正在用eclipse链接执行JPA（从表生成动态实体）。 我的persistence.xml看起来像

<persistence-unit name="abcLink" 
     transaction-type="RESOURCE_LOCAL"> 
     <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
     <mapping-file>META-INF/eclipselink-orm.xml</mapping-file>   
     <properties> 
      <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" /> 
      <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost/netspectiveauthentication?zeroDateTimeBehavior=convertToNull"/> 
      <property name="javax.persistence.jdbc.user" value="root" /> 
      <property name="javax.persistence.jdbc.password" value="" /> 
      <property name="eclipselink.ddl-generation" value="create-tables" /> 
      <property name="eclipselink.logging.level" value="INFO" /> 
      <property name="eclipselink.logging.exceptions" value="true" />  
     </properties> 
    </persistence-unit> 

和 在供应商类

String persistenceUnitName = "abcLink";  
      EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnitName,properties); 
      emf.createEntityManager();     
      return new JPAProducer(emf, "abcd", 20); 

我用这对ODATA4j实施，使属性将通过覆盖 同时运行I” ODataProducer创建功能 得到m得到以下错误

javax.persistence.PersistenceException: Exception [EclipseLink-28017] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.EntityManagerSetupException 
Exception Description: Unable to predeploy PersistenceUnit [AuthenticationServiceEclipseMysqlLink] in invalid state [DeployFailed]. 
Internal Exception: javax.persistence.PersistenceException: Exception [EclipseLink-28019] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.EntityManagerSetupException 
Exception Description: Deployment of PersistenceUnit [AuthenticationServiceEclipseMysqlLink] failed. Close all factories for this PersistenceUnit. 
Internal Exception: Exception [EclipseLink-7328] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.ValidationException 
Exception Description: When using VIRTUAL access a DynamicClassLoader must be provided when creating the entity manager factory using the eclipselink property [eclipselink.classloader]. That is, createEntityManagerFactory(String persistenceUnitName, Map properties) and add a new DynamicClassLoader() to the Map properties. 
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:1226) 
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:134) 
    at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source) 

我觉得错误很明显但我想知道，我如何通过属性给动态类加载器。或者任何其他方式摆脱此错误。

Answer 1

看看this example，在main方法的开头。