JPA仪器仪表
在 JPA 中打开 EntityManagerFactory 时是否可以看到生成的 DDL？我似乎遇到了一些问题，但没有产生错误。我没有看到任何类型的日志文件，也没有输出写入 StdOut 或 StdErr。我在 src/main/resources 中有一个 log4j.properties：
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
log4j.rootLogger=debug, stdout
log4j.logger.org.hibernate=debug
log4j.logger.org.hibernate.SQL=debug
log4j.logger.org.hibernate.engine.CascadingAction=debug
log4j.logger.org.hibernate.tool.hbm2ddl=debug
我什至不确定该文件是否被识别。有什么方法可以让我找到答案吗？如何更好地了解 Hibernate 和/或 JPA 的操作？我基本上没有输出（除了我的程序中的 System.out.println() ）。
Is it somehow possible to see the DDL produced when opening a EntityManagerFactory in JPA? I seem to be having some problems but no errors are produced. I don't see any sort of log file and no output is written to StdOut or StdErr. I have a log4j.properties in src/main/resources:
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
log4j.rootLogger=debug, stdout
log4j.logger.org.hibernate=debug
log4j.logger.org.hibernate.SQL=debug
log4j.logger.org.hibernate.engine.CascadingAction=debug
log4j.logger.org.hibernate.tool.hbm2ddl=debug
I'm not even sure if the file is recognized. Is there a way I can find that out? How can I get better insight into the actions of Hibernate and/or JPA? I basically have no output (except the System.out.println()'s in my program).
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尝试在持久性单元内的 persistence.xml 中添加以下内容。
不太确定它是否会给您提供您正在寻找的信息，但应该会给您一些额外的输出。
Try adding the following in your persistence.xml, within the persistence unit.
Not too sure whether it will give you the info you're looking for but should give you some extra output.
要查明您的 log4j.properties 文件是否已被选中，您可以在其中故意引入错误（例如，拼错
ConsoleAppender类名）。如果文件确实被拾取，Log4j 应该爆炸或者至少在控制台中显示错误。就 DDL 而言，我使用 Hibernate 和 Spring 而不是 JPA，所以 YMMV，但是：
最好的选择是查看 EntityManagerFactory 代码，找出脚本的执行位置，并查看其周围是否有任何日志记录；然后你就会知道你需要在 log4j.properties 中配置什么包
To find out whether your log4j.properties file is picked up you can introduce a deliberate error into it (misspell
ConsoleAppenderclass name, for example). Log4j should either blow up or at least show an error in a console if the file is indeed picked up.As far as DDL goes,I'm using Hibernate with Spring rather than JPA so YMMV, but:
Your best bet would be to take a look at EntityManagerFactory code to figure out where the script is executed and see if there's any logging going on around it; you would then know what package you need to configure in your log4j.properties
这并不是说这解决了您的第一个问题，但我总是将我的应用程序名称添加到 .ConversionPattern 中。这样我就可以快速查明更改是否已应用，并将多个应用程序记录到同一文件中
Not that this solves your first question, but I always add mye applications name to the .ConversionPattern. That way I can quickly find out if the changes are applied, and log more than one application to the same file