Persistence.xml未被Helidon处理

Question

对于我的Helidon应用程序，我想在Hibernate中使用H2数据库，所以我做了以下配置：

    <persistence-unit name="h2" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.archive.autodetection" value="class" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
            <property name="hibernate.connection.driver_class" value="org.h2.Driver" />
            <property name="hibernate.connection.url" value="jdbc:h2:h2" />
            <property name="hibernate.connection.user" value="sa" />
            <property name="hibernate.hbm2ddl.auto" value="update" />
        </properties>
    </persistence-unit>

但是，我的helidon应用程序没有用以下参数连接到数据库。据我所见，它只是忽略了这个配置。尽管我添加了以下依赖项：

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.helidon.integrations.cdi</groupId>
    <artifactId>helidon-integrations-cdi-eclipselink</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.helidon.integrations.cdi</groupId>
    <artifactId>helidon-integrations-cdi-jta-weld</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.helidon.integrations.cdi</groupId>
    <artifactId>helidon-integrations-cdi-datasource-hikaricp</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.helidon.integrations.cdi</groupId>
    <artifactId>helidon-integrations-cdi-jpa</artifactId>
    <scope>runtime</scope>
</dependency>

如何用Helidon连接到h2数据库？

Answer 1

Helidon提供了容器管理的JPA集成，这意味着在META-INF/persistence.xml文件中没有指定JDBC信息的许多其他事情。容器管理的JPA的全部要点是所有这些东西都是为您处理的，所以您的persistence.xml类路径资源应该提到一个启用JTA的数据源名称，该名称应该用于连接到数据库。

请看下面的示例：https://github.com/helidon-io/helidon/tree/helidon-3.x/examples/integrations/cdi/jpa

1. 您在microprofile-config.properties文件中指定了DataSource属性：

javax.sql.DataSource.ds1.dataSourceClassName=org.h2.jdbcx.JdbcDataSource
javax.sql.DataSource.ds1.dataSource.url=jdbc:h2:mem:test;DB_CLOSE_DELAY=-1
javax.sql.DataSource.ds1.dataSource.user=db_user
javax.sql.DataSource.ds1.dataSource.password=user_password

1. persistence.xml应该是这样的：

<persistence xmlns="https://jakarta.ee/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="https://jakarta.ee/xml/ns/persistence https://jakarta.ee/xml/ns/persistence/persistence_3_0.xsd"
             version="3.0">

    <persistence-unit name="pu1" transaction-type="JTA">
        <jta-data-source>ds1</jta-data-source>
        <class>com.example.myproject.Pokemon</class>
        <class>com.example.myproject.PokemonType</class>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
            <property name="jakarta.persistence.sql-load-script-source" value="META-INF/init_script.sql"/>
            <property name="jakarta.persistence.schema-generation.database.action" value="drop-and-create"/>
        </properties>
    </persistence-unit>
</persistence>

EntityManager注入

    @PersistenceContext(unitName = "pu1")
    private EntityManager entityManager;

我强烈鼓励您使用Helidon Starter为您生成初始项目：https://helidon.io/starter/3.0.2?flavor=mp&step=5&app-type=database