如何在不是来自JNDI的JPA EntityMangerFactory上设置数据源 [英] How to set a DataSource on a JPA EntityMangerFactory that is not from JNDI

问题描述

我对JPA还是很陌生，曾经使用过JDO(DataNucleus)和Hibernate.

I'm pretty new to JPA, having used JDO (DataNucleus) and Hibernate.

我了解了如何为JPA配置设置 persistence.xml ，但是我需要进行一些调整.我不想在XML中指定 DataSource ，而是要向 EntityManagerFactory 提供实际的 DataSource 对象.我之所以需要这样做，是因为我创建并管理了自己的 DataSource 对象，并且不依赖容器来执行此操作，因此我无法(也不想)查找 DataSource 通过 persistence.xml 中的JNDI名称.

I get how to set up persistence.xml for the JPA configuration, but I need to make one tweak. Instead of specifying the DataSource in the XML, I want to provide the actual DataSource object to the EntityManagerFactory. I need to do this because I create and manage my own DataSource objects and do not rely on the container to do so, thus I cannot (and do not want to) look up the DataSource via a JNDI name in persistence.xml.

那么，如何为 EntityManagerFactory 提供一个 DataSource 对象，而不是在 persistence.xml 中指定它?我无法想象这很难很难，但是我似乎找不到它，而且我到处都是.

So, how to I provide a DataSource object to the EntityManagerFactory rather than specifying it in persistence.xml? I can't imagine it's hard to do but I can't seem to find it, and I've looked all over the place.

如果有什么帮助，我将使用Hibernate 4作为JPA提供程序(实际上，我是从3.6过渡到4，其中 Ejb3Configuration 类消失了).希望我可以采用非Hibernate特定的方式来完成此操作，但是如果我必须使用Hibernate特定的API，这并没有什么大不了的.

If it helps at all, I'm using Hibernate 4 as the JPA provider (actually, I'm transitioning from 3.6 to 4, where the Ejb3Configuration class is gone). Hopefully I can do it in a non-Hibernate specific way, but it's not a huge deal if I have to use Hibernate specific APIs.

谢谢！

-瑞安

推荐答案

我自己也想不出办法，所以我用Spring来做.这并不一定很糟，除了它需要我进口六个以前不打算使用的罐子外.无论如何，我最终还是将它们用于其他用途，但对于JPA而言，这是一个真正的失败，它甚至不能使用API​​来设置DataSource，而必须依赖于容器提供的DataSource.

I couldn't figure out any way to do it myself so I used Spring to do it. That's not necessarily bad, except that it required me to import a half dozen or so jars that I previously wasn't intending to use. I ended up using them for other things anyway, but still, I think it's a real failure on the part of JPA that one can't even use the API to set a DataSource but must instead rely on a container-provided DataSource.

我用Spring的 LocalContainerEntityManagerFactoryBean 来完成这项工作.它从 persistence.xml 中读取配置数据，然后我通过Spring API设置 DataSource .Spring使用 DataSource 覆盖 persistence.xml 中定义的内容.

I used Spring's LocalContainerEntityManagerFactoryBean to do the work. It reads the configuration data from persistence.xml and I then set the DataSource via the Spring API. Spring uses the DataSource to override what was defined in persistence.xml.

这是代码的样子.请注意对 afterPropertiesSet 方法的调用.这是必需的，因为我的应用程序不将Spring用于依赖项注入或AOP，而是将Guice用于这些任务.如果您不调用 afterPropertiesSet 方法，则对 getNativeEntityManagerManagerFactory 的调用将返回null.

Here's what the code looks like. Note the call to the afterPropertiesSet method. This is required because my application does not use Spring for dependency injection or AOP, but instead uses Guice for those tasks. If you don't call the afterPropertiesSet method then the call to getNativeEntityManagerFactory returns null.

  LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
  factoryBean.setDataSource(dataSource);
  factoryBean.setPersistenceUnitName("persistenceUnitName");
  factoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
  factoryBean.afterPropertiesSet();

  EntityManagerFactory factory = factoryBean.getNativeEntityManagerFactory();

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