Maven 无法定位持久性单元

Question

您好，我正在使用 maven 和 jpa 构建一个 java 应用程序。我有一个数据库项目，它是我的主应用程序的依赖项。数据库项目在开发模式下功能齐全，但是当我生成 jar 时，出现错误 Unable to locate persistence unit。我将 persistence.xml 文件放在一个文件夹 META-INF 中，该文件夹与我的 jar 文件位于同一文件夹中。我有以下 persistence.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
        version="2.0">

        <persistence-unit name="user-db">
            <provider>org.hibernate.ejb.HibernatePersistence</provider>
            <class>com.main.application.User</class>
            <properties>
                <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
                <property name="hibernate.hbm2ddl.auto" value="update" />
                <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
                <property name="hibernate.connection.username" value="user" />
                <property name="hibernate.connection.password" value="pwd" />
                <property name="hibernate.connection.url" value="jdbc:mysql://127.0.0.1/users_db" />
            </properties>
        </persistence-unit>
</persistence>

堆栈跟踪：

> Exception in thread "main" java.lang.reflect.InvocationTargetException
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:497)
>         at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
> Caused by: javax.persistence.PersistenceException: Unable to locate
> persistence units
>         at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:84)
>         at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:71)
>         at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:52)
>         at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:48)
>         at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:32)
>         at com.user.Dao.<init>(Dao.java:22)
>         at com.user.Dao.get(Dao.java:26)
>         at com.user.UserHandler.<init>(UserHandler.java:61)
>         at com.user.Main.main(Main.java:10)
>         ... 5 more Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range:
> -1
>         at java.lang.String.substring(String.java:1967)
>         at org.hibernate.boot.archive.internal.ArchiveHelper.getJarURLFromURLEntry(ArchiveHelper.java:45)
>         at org.hibernate.jpa.boot.internal.PersistenceXmlParser.parsePersistenceXml(PersistenceXmlParser.java:105)
>         at org.hibernate.jpa.boot.internal.PersistenceXmlParser.doResolve(PersistenceXmlParser.java:84)
>         at org.hibernate.jpa.boot.internal.PersistenceXmlParser.locatePersistenceUnits(PersistenceXmlParser.java:66)
>         at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:80)
>         ... 13 more

Answer 1

当您使用 JPA-2.0 时，以下是 Java EE 6 JPA documentation 的摘录，可能会有用：

Persistent units can be packaged as part of a WAR or EJB JAR file or can be packaged as a JAR file that can then be included in an WAR or EAR file.

If you package the persistent unit as a set of classes in an EJB JAR file, persistence.xml should be put in the EJB JAR’s META-INF directory.

If you package the persistence unit as a set of classes in a WAR file, persistence.xml should be located in the WAR file’s WEB-INF/classes/META-INF directory.

If you package the persistence unit in a JAR file that will be included in a WAR or EAR file, the JAR file should be located in either

The WEB-INF/lib directory of a WAR

The EAR file’s library directory

Answer 2

我发现我导出项目的方式不对。我看到了 this 线程，这是那里的建议，现在一切似乎都有效。

Maven 无法定位持久性单元

Maven Unable to locate persistence unit

java

maven

jpa

persistence

jpa-2.0