JPA EntityManager详解

1.获得EntityManager对象 

两种方式：1 @PersistenceContex注入 2 JNDI获得 

private EntityManager em;

@PersistenceContext
public void setEntityManager(EntityManager em) {
this.em = em;
}

2.配置（这是用ant）

 

META-INF配置

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">

WEB-INF/lib/crmbase.jar