我正在使用 Eclipse 的内部 glassfish 3.1 插件以及我安装的 derby 数据库（它显示在 Eclipse 的数据库开发人员视图中的数据源资源管理器上），并且我正在摸索着获取ORM 的工作使我可以开发一个应用程序，使用 Eclipselink 来实现 JPA 并使用 EJB 保存数据。
我知道我需要配置 persistence.xml 文件，但我不知道其中需要什么，各个字段名称的含义是什么。我觉得 persistence.xml 的目的是告诉 Glassfish 在哪里可以找到存储所有内容的数据库，以及使用哪个 JPA 实现来进行存储。
我有很多问题。
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对于代表数据库中对象的每个类，我是否必须有一个持久性条目？因此，如果我有一个 Book 类和一个 Library 类，我是否需要 persistence.xml 中的两个条目，或者我可以只做一个为它们提供服务的案例吗？
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在哪里可以找到有关如何配置 persistence.xml 文件的更多信息。 配置它的信息，但没有任何内容解释各个位以及如何从高级别配置它们。
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一旦我正确设置了 persistence.xml 文件，我还需要做什么来确保 ORM 实现正确地为我的 @annotated 类提供服务？我需要在 Glassfish 中配置什么吗？
I'm using the internal glassfish 3.1 plugin for Eclipse, along with a derby database I installed (it shows up on the datasource explorer in the Database Developer view in Eclipse), and I'm fumbling at the "last" step of getting the ORM working so that I can develop an app that persists data with EJBs using Eclipselink for the JPA implementation.
I know I need to configure the persistence.xml file, but I'm at a loss for what needs to be in it, what the individual field names mean. I feel like the purpose of the persistence.xml is to tell Glassfish where to find the database to store everything in, and which JPA implementation to use to do that storing.
I have a bunch of questions.
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Do I have to have a persistence entry for each class that represents an object in the database? So if I had a Book class and a Library class, would I need two enteries in persistence.xml or could I just do one case that services them both?
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Where can I find more information about how to configure the persistence.xml file IN GENERAL. I have found tons of very specific tutorials with information on how to configure it in X, Y, or Z setting, but nothing that explains the individual bits, and how you'd configure them from a high level.
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Once I've setup my persistence.xml file correctly, what else do I need to do to ensure that my @annotated classes are going to be serviced by the ORM implementation correctly? Is there something I need to configure in Glassfish?
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我不是专家，但是...
1) 是的，根据我的经验，每个课程都需要一个条目。可能会有例外，但我对它们不熟悉。
2) [http://wiki.eclipse.org/EclipseLink/] 是一个很好的起点。
[http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Configuration/JPA/persistence.xml] 有一些您可能已经知道的详细信息。我自己很难找到完美的资源。我倾向于发现到处都是支离破碎的信息。
3）一般来说，我的大部分 persistence.xml 文件都是由 eclipselink 自动生成的。
从 glassfish 管理控制台创建连接池和 JDBC 资源后
我必须将
添加到 persistence.xml。[1]
我添加了这些属性，以便我的身份列可以使用 JPA 自动递增。
尝试这两个教程以更好地了解其工作原理：
[1] http://programming.manessinger.com/tutorials/an-eclipse-glassfish-java-ee-6-tutorial/#heading_toc_j_24
http://itsolutionsforall.com/index.php
[*抱歉，我目前无法发布超过 2 个链接]
I'm not an expert but...
1) Yes, in my experience you need an entry for each class. There could be exceptions to this but I am unfamiliar with them.
2) [http://wiki.eclipse.org/EclipseLink/] is a good place to start.
[http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Configuration/JPA/persistence.xml] has some details that you may already know. I've have trouble finding a perfect resource myself. I've tended to find information fragmented all over the place.
3) In general most of my persistence.xml file has been generated automatically by eclipselink.
After I creating a connection pool and JDBC resource from the glassfish Administration Console
I had to add my
<jta-data-source>jdbc/your_name</jta-data-source>to persistence.xml.[1]
I added these properties so my identity columns would auto-increment using JPA.
Try these two tutorials to get a better understanding of how it works:
[1] http://programming.manessinger.com/tutorials/an-eclipse-glassfish-java-ee-6-tutorial/#heading_toc_j_24
http://itsolutionsforall.com/index.php
[*apologies I can't post more than 2 links at the moment]