Hibernate 的两个配置文件的目的是什么? [英] what is the purpose of two config files for Hibernate?

问题描述

这是我目前的项目结构:

This is my current project structure:

pom.xml
/src
  /main
    /resources
      hibernate.cfg.xml
      /META-INF
        persistence.xml

我在两个文件(hibernate.cfg.xml 和 persistence.xml)中有非常相似的配置参数，这看起来很奇怪，但这是我在许多文件中看到的在线示例和教程.我不明白为什么我需要两个文件.是否可以只与一个一起工作?请解释.

I have very similar configuration params in both files (hibernate.cfg.xml and persistence.xml), which looks strange, but this is what I saw in many online examples and tutorials. I can't understand why do I need to have two files. Is it possible to work just with one? Please explain.

ps.例如，我应该在两个文件中都声明 hibernate.dialect 还是一个就足够了?如果是这样，使用哪个?

ps. For example, should I declare hibernate.dialect in both files, or just one will be enough? If so, which one to use?

推荐答案

如果您正在使用 Hibernate 的专有 API，您将需要 hibernate.cfg.xml.如果您使用 JPA，即 Hibernate EntityManager，您将需要 persistence.xml.

If you are using Hibernate's proprietary API, you'll need the hibernate.cfg.xml. If you are using JPA i.e. Hibernate EntityManager, you'll need the persistence.xml.

因此，当您使用Hibernate 专有 API 或 JPA 时，通常不需要两者.

So you generally don't need both as you use either Hibernate proprietary API or JPA.

但是，如果您正在使用 Hibernate 专有 API 并且已经有一个 hibernate.cfg.xml(和 hbm.xml XML 映射文件) 但是想开始使用JPA，可以通过引用hibernate.ejb中的persistence.xml中的hibernate.cfg.xml来重用现有的配置文件.cfgfile 属性 - 因此有两个文件.重用现有的 hbm.xml 文件是 IMO 一个现实的场景，可以证明同时保留两者(即使从长远来看我可能会迁移到 JPA 注释).

However, if you were using Hibernate Proprietary API and already have a hibernate.cfg.xml (and hbm.xml XML mapping files) but want to start using JPA, you can reuse the existing configuration files by referencing the hibernate.cfg.xml in the persistence.xml in the hibernate.ejb.cfgfile property - and thus have both files. Reusing existing hbm.xml files is IMO a realistic scenario that could justify keeping both (even if I'd probably migrate to JPA annotations on the long run).

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