动态更改持久性单元-JPA

保持持久性单元文件（Persistence.xml）不变。您可以按如下所示覆盖其中的属性。

EntityManagerFactory managerFactory = null;Map<String, String> persistenceMap = new HashMap<String, String>();persistenceMap.put("javax.persistence.jdbc.url", "<url>");persistenceMap.put("javax.persistence.jdbc.user", "<username>");persistenceMap.put("javax.persistence.jdbc.password", "<password>");persistenceMap.put("javax.persistence.jdbc.driver", "<driver>");managerFactory = Persistence.createEntityManagerFactory("<current persistence unit>", persistenceMap);manager = managerFactory.createEntityManager();