如何以编程方式将持久化上下文注入不同的数据源 [英] How to inject persistence context to different data source programmatically

问题描述

在标准 EJB 3 中，当注入实体管理器时，持久化单元(指数据源)被硬编码到注解中:(或者 xml 文件)

In standard EJB 3, when injecting entity manager, persistence unit (which refers to datasource) is hardcoded into annotation: (or alternatively xml file)

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

有没有办法使用实体管理器，但在运行时按名称选择数据源?

Is there a way to use an entity manager but to select data source by name at runtime?

推荐答案

使用 EclipseLink，您可以设置在您的应用服务器中配置的 DataSource.

Using EclipseLink, You can set a DataSource configured in your app server.

import org.eclipse.persistence.config.PersistenceUnitProperties;
...


....
Map props = new HashMap();  
props.put(PersistenceUnitProperties.JTA_DATASOURCE, "dataSource");  
EntityManagerFactory  emf = Persistence.createEntityManagerFactory("UNIT_NAME", props);
EntityManager em = emf.createEntityManager();

PU_NAME 是指在文件 persistence.xml
中使用的名称dataSource 将应用服务器中用于 jdbc 资源的名称称为jdbc/sample"

PU_NAME refers to the name used in the file persistence.xml
dataSource refers name used in the app server for the jdbc Resource as "jdbc/sample"

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