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POReferring to the artifactId of a maven dependency jar from persistence.xml
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  1. POReferring to the artifactId of a maven dependency jar from persistence.xml
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    copied!<p>We're working with JPA and are trying to stick to standard spec (and avoiding Hibernate-specific features).</p> <p>We use one project (let's call it X) inside another project (A) as a Maven dependency.</p> <p>We need JPA to scan project X for Entities as well as scanning project A.</p> <p>To that end, we've added a line </p> <pre><code>&lt;jar-file&gt;lib/X-v5-4.0.jar&lt;/jar-file&gt; </code></pre> <p>inside</p> <pre><code>&lt;persistence-unit&gt; </code></pre> <p>in persistence.xml. This works fine.</p> <p>The issue we still have is that we now need to specify the version of project X in not only pom.xml but also in persistence.xml. This is a recipe for problems with deploys in the future.</p> <p>We've come up with a system using Maven resource filtering:</p> <pre><code>&lt;jar-file&gt;lib/X-v5-${x-version}.jar&lt;/jar-file&gt; </code></pre> <p>in persistence.xml and </p> <pre><code>&lt;properties&gt; &lt;x-version&gt;4.0&lt;/x-version&gt; &lt;/properties&gt; </code></pre> <p>and ${x-version} in pom.xml.</p> <p>This works but is still not perfect, as we'll have to remember to update the version number in a non-standard location each time project X gets a new version.</p> <p>Ideally, we'd like to have a situation where we can adjust version information in the dependency part of pom.xml and changes would propagate to persistence.xml automatically. We'd reduce a lot of possible errors in future deploys this way.</p> <p>Is this possible?</p> <p>EDIT (OUR SOLUTION):</p> <p>we have added a file named jpa.xml. We define an entityManagerFactory, a persistenceAnnotationBeanPostProcessor and a transactionManager in it. The important part here is the entityManagerFactory bean. It has a property "packagesToScan" that allows you to indicate specific packages to scan for entities to put in the persistence context.</p> <p>A code snippet:</p> <pre><code>&lt;bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"&gt; &lt;property name="dataSource" ref="jpaDataSource" /&gt; &lt;property name="loadTimeWeaver"&gt; &lt;bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" /&gt; &lt;/property&gt; &lt;property name="packagesToScan"&gt; &lt;list&gt; &lt;value&gt;org.com.our.external.library.package1&lt;/value&gt; &lt;value&gt;org.com.our.external.library.package2&lt;/value&gt; &lt;value&gt;org.com.our.external.library.package3&lt;/value&gt; &lt;/list&gt; &lt;/property&gt; &lt;/bean&gt; </code></pre> <p>I'm sure you see the advantage: as we are referring to these libraries by package signature, we no longer have to worry about jar version numbers.</p>
 

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