以下是我们的 wildfly 8.x/9.x ejb 应用程序中的工作示例:
首先,在 persistence.xml 中定义每个持久单元的所有类,可以关闭未列出的类以禁用自动发现。
持久性.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="primary">
<jta-data-source>java:jboss/datasources/primary_ds</jta-data-source>
<class>whatever.primary.model.SomeEntity</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties> ... </properties>
</persistence-unit>
<persistence-unit name="secondary">
<jta-data-source>java:jboss/datasources/secondary_ds</jta-data-source>
<class>whatever.secondary.model.AnotherEntity</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties> ... </properties>
</persistence-unit>
</persistence>
如果您使用 JBoss Developer Studio,请忽略该警告(这只是一个 Eclipse 缺陷):
定义了多个持久性单元 - 仅第一个持久性单元将被识别
资源.java
package whatever.util;
import javax.annotation.Resource;
import javax.enterprise.inject.Produces;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.sql.DataSource;
public class Resources {
@Produces
@PersistenceContext(unitName = "primary")
private EntityManager emPrimary;
@Produces
@PersistenceContext(unitName = "secondary")
private EntityManager emSecondary;
@Produces
@Resource(lookup = "java:jboss/datasources/primary_ds")
private DataSource dsPrimary;
@Produces
@Resource(lookup = "java:jboss/datasources/secondary_ds")
private DataSource dsSecodnary;
}
Dao 初级示例
package whatever.dao;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@Stateless
public class DaoPrimaryExample {
@PersistenceContext(unitName = "primary")
private EntityManager em;
public void create(SomeEntity entity) {
em.persist(entity);
}
}
Dao 二级示例
package whatever.dao;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@Stateless
public class DaoSecondaryExample {
@PersistenceContext(unitName = "secondary")
private EntityManager em;
public void create(AnotherEntity entity) {
em.persist(entity);
}
}
重要提示:如果您计划在同一事务中使用展位持久性单元,则应使用 XA 数据源。