OpenJPA 在代码中创建 EntityManager，无需 persistence.xml，具有属性

Question

我需要在没有 persistence.xml 的代码中创建 EntityManager ... 我有

props.put("openjpa.ConnectionURL", "jdbc:sqlserver://databasehost:3306; DatabaseName=dbname; selectMethod=cursor;create=true");
    props.put("openjpa.ConnectionDriverName","com.mysql.jdbc.Driver");
    props.put("openjpa.ConnectionUserName", "dbname");
    props.put("openjpa.ConnectionPassword", "password");
    props.put("openjpa.jdbc.SynchronizeMappings", "buildSchema");
    props.put("openjpa.Log", "DefaultLevel=WARN, Runtime=INFO, Tool=INFO, SQL=TRACE");
    props.put("openjpa.RuntimeUnenhancedClasses", "supported");

    EntityManagerFactory factory = Persistence.createEntityManagerFactory("wp");
    em = factory.createEntityManager(props);

..并且当 em =factory.createEntityManager(props) 被调用时我得到：

javax.persistence.PersistenceException: No persistence providers available for "wp" after trying the following discovered implementations: org.apache.openjpa.persistence.PersistenceProviderImpl
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:182)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:72)
    at dao.wp.WP_EMH.getCurrentEntityManager(WP_EMH.java:27)

我知道没有提到由标记

PROVIDER- org.apache.openjpa.persistence.PersistenceProviderImpl - / 表示的 persistence.xml 中的内容PROVIDER

我应该如何将其添加到属性中？或者如何解决？ 我的第二个问题是在 persistence.xml 中添加了实体类。如何用属性来解决这个问题？

谢谢

Answer 1

该方法

javax.persistence.Persistence.createEntityManagerFactory(
    String persistenceUnitName);

需要来自 persistence.xml 的配置。尝试将您的属性映射提供给

javax.persistence.Persistence.createEntityManagerFactory(
    String persistenceUnitName, Map properties);

显然，属性集不完整；例如，它缺少持久的类名：

properties.put("openjpa.MetaDataFactory", "jpa(Types=FQN.class1;FQN.class2;...)");