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我創建了一個像我的工作論文一樣的Web應用程序。此應用程序使用的整個堆棧的Java EE 6:JPA2,EJB,JSF,RichFaces的....Vaadin JPACtainer不起作用
現在我想我的應用程序的UI從RichFaces的改變Vaadin。第一個問題始於使用JPA容器。我無法獲得entitymanager的實例。
這是我的persistence.xml
<?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="primary">
<jta-data-source>java:jboss/VaadinDS</jta-data-source>
<class>org.mypackage.entity.Utente</class>
<class>org.mypackage.entity.Indirizzo</class>
<class>org.mypackage.entity.Paese</class>
<properties>
<!-- Properties for Hibernate -->
<property name="hibernate.hbm2ddl.auto" value="create" />
<property name="hibernate.show_sql" value="false" />
</properties>
</persistence-unit>
</persistence>
這是我singelton類,我想獲得的EntityManager
public class Utility {
private static EntityManager entityManager;
public Utility() {
// TODO Auto-generated constructor stub
}
public static EntityManager getInstance(){
if(entityManager == null)
entityManager = JPAContainerFactory.createEntityManagerForPersistenceUnit("primary");
return entityManager;
}
}
的我實例,但不工作,我發現總是遵循錯誤:
[com.vaadin.server.DefaultErrorHandler] (http-localhost-127.0.0.1-8080-1) : java.lang.NullPointerException
我在哪裏錯了?
你爲什麼要使用EJB和會話Bean之外的EntityManager?也許這有助於:https://vaadin.com/book//page/jpacontainer.entityprovider.html – raffael