Hibernate SchemaExport和Persistence单元

Question

上一个问题的后续问题:使用Hibernate 4生成SQL DB创建脚本

目标是让命令行工具能够生成具有给定持久性单元的SQL模式的文件(类似于Hibernate Tools中存在的hibernatetool-hbm2ddl Ant任务).

根据我之前的问题的答案,这可以实现org.hibernate.tool.hbm2ddl.SchemaExport.

而不是将所有实体添加到Configuration(如上一个答案中所建议的)我想指定一个PersistenceUnit.

是否可以在Hibernate中添加持久性单元Configuration？

就像是

Properties properties = new Properties();
properties.put( "hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect" );
...
EntityManagerFactory entityManagerFactory =
    Persistence.createEntityManagerFactory( "persistentUnitName", properties );
Configuration configuration = new Configuration();

... missing part ...

SchemaExport schemaExport = new SchemaExport( configuration );
schemaExport.setOutputFile( "schema.sql" );
...

按照评论中的要求编辑样本persistence.xml.每个类都注明了@Entity

<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_1_0.xsd"
    version="1.0"
>

    <persistence-unit
        name="doiPersistenceUnit"
        transaction-type="JTA"
    >

        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>jdbc/doi</jta-data-source>


        <class>ch.ethz.id.wai.doi.bo.Doi</class>
        [...]
        <class>ch.ethz.id.wai.doi.bo.DoiPool</class>

        <exclude-unlisted-classes>true</exclude-unlisted-classes>

        <properties>
            <property name="hibernate.show_sql"                     value="false" />
            <property name="hibernate.format_sql"                   value="false" />
            <property name="hibernate.connection.characterEncoding" value="utf8" />
            <property name="hibernate.connection.charSet"           value="utf8" />
        </properties>

    </persistence-unit>

</persistence>

Answer 1

好吧,如果您的类是通过xml映射映射hbm的 - 您可以Configuration使用config.addJar(myJarFile)和将包含xmls的documnets或jar文件直接添加到实例config.add(myXmlFile).

但是,如果您希望扫描带注释的类 - 我知道Hibernate没有这么简单的选项(addPackage添加元数据而不是类).

您可以实现自己的扫描逻辑并添加所有带注释的类config.addAnnotatedClass(myAnnotatedClass)(或者根据您知道的包含ORM类的特定包来执行它,因此可以节省一些时间).

更新2

哦,甚至更好,你可以ManagedType通过getManagedTypes()以下方式迭代持久性单元:

EntityManagerFactory entityManagerFactory =
    Persistence.createEntityManagerFactory( unitName, config.getProperties() );
final Set<ManagedType<?>> managedTypes =
    entityManagerFactory.getMetamodel().getManagedTypes();
    for ( ManagedType<?> managedType : managedTypes ) {
    final Class<?> javaType = managedType.getJavaType();
    config.addAnnotatedClass( javaType );
}

UPDATE

您可以确定PersistenceUnit每个Entity- 不必解析XML -通过对相关检查EntityManagerFactory:

Class aClass = ... // get the class from your scanning
EntityManagerFactory entityManagerFactory =
    Persistence.createEntityManagerFactory( unitName, config.getProperties() );
ManagedType<?> managedType = null;
try {
    managedType = entityManagerFactory.getMetamodel().managedType( aClass );
} catch ( IllegalArgumentException e ) {
    // happens when aClass isn't a type managed by the persistence unit
}
if ( managedType != null ) {
    config.addAnnotatedClass( aClass );
}

确保Configuration为每个持久性单元使用不同的实例.否则,带注释的类只会累积,DDL也会累积.

我尝试了它并且效果很好 - 为两个不同的持久性单元打印了两个不同的DDL.