在java EE 6中：什么时候可以更改EntityManager的属性？

Question

@Stateless
public class Boundary {

    @PersistenceContext EntityManager em;

    @PostConstruct
    private void init()  {
        em.setProperty("eclipselink.oracle.proxy-type", OracleConnection.PROXYTYPE_USER_NAME);
        em.setProperty(OracleConnection.PROXY_USER_NAME, "pool[user_a]");
        em.setProperty(OracleConnection.PROXY_USER_PASSWORD, "pool");
        em.setProperty(OracleConnection.PROXY_ROLES, "pool_user");
        em.setProperty("eclipselink.jdbc.exclusive-connection.mode", "Always");
        em.setProperty("eclipselink.jdbc.exclusive-connection.is-lazy", "false");
    }

    public void save() {
        em.merge(new AnEntity());
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<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="ProxyUserPU" transaction-type="JTA">
    <jta-data-source>SecondTry</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
    <properties>
      <property name="eclipselink.target-database" value="Oracle"/>
      <property name="eclipselink.jdbc.exclusive-connection.is-lazy" value="true"/>
    </properties>
  </persistence-unit>
</persistence>

Answer 1

我不认为后构式是这个的正确位置。

每个事务边界上的持久性上下文都绑定了一个新的EntityManager，因此您需要在每个事务性SessionBean方法开始时设置这些属性。您可能还可以使用EclipseLink中的SessionEvents来配置属性。

如果属性是固定的，那么也可以将它们放在persistence.xml中。