JPA 与 H2 数据库的连接

Question

我正在开发一个带有 JPA 的 hibernate 项目，并尝试使用 H2（嵌入式数据库）获取工作 persistence.xml。

Persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    version="1.0">

    <persistence-unit name="DefaultPersistenceUnit"
        transaction-type="RESOURCE_LOCAL">

        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <class>entity.user</class>
        <properties>
           <property name="hibernate.connection.url" value="jdbc:h2:/~test" /> -->
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"></property>
            <property name="hibernate.connection.driver_class" value="org.h2.Driver" />
            <property name="hibernate.connection.password" value="admin" />
            <property name="hibernate.connection.username" value="admin" />
        </properties>
    </persistence-unit>
</persistence>

但是我的这不起作用，我总是收到错误

“无法创建EntityManagerFactory”

EntityManagerFactory emf = Persistence.createEntityManagerFactory("DefaultPersistenceUnit");

。谁能给我提供有效的 persistence.xml 吗？

Answer 1

你用的是Spring吗？如果是这样，只要容器不提供 EntityManagerFactory，您就可以尝试此操作

<bean id="entityManagerFactory"
      class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="generateDdl" value="true" />
            <property name="database" value="H2" />
        </bean>
    </property>
    <property name="persistenceUnitName" value="DefaultPersistenceUnit" />
</bean>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

<bean id="dataSource"
      class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.h2.Driver" />
    <property name="url" value="jdbc:h2:database/~test" />
    <property name="username" value="sa" />
    <property name="password" value="" />
</bean>