database - JPA 实体 - 指定持久性单元？

Question

我有一个使用多个持久性单元的 JavaEE 项目。有没有办法指定特定 JPA 实体属于哪个持久性单元？一些实体在一个数据源中，而其他实体在我的第二个数据源中。有没有办法使用注释来区分两者？

Answer 1

指定哪个持久单元是Entity属于，使用 persistence.xml文件:

<persistence version="2.0" 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">

    <persistence-unit name="user" transaction-type="JTA">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>jdbc/myApp</jta-data-source>
        <class>com.company.User</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <properties>
            <!-- properties -->
        </properties>
    </persistence-unit>

    <persistence-unit name="data" transaction-type="JTA">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>jdbc/myApp_data</jta-data-source>
        <!--<mapping-file>META-INF/myApp_entities.xml</mapping-file> You can also use mapping files.-->
        <class>com.company.Data</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <properties>
            <!-- properties -->
        </properties>
    </persistence-unit>
</persistence>

注意 <exclude-unlisted-classes /> 的使用.