PersistanceUnit註釋不注入

我有一個小型的教育項目。 JPA，Servlet的JSP。現在我想用PersistanceUnit註釋：PersistanceUnit註釋不注入

public class UsersListServlet extends HttpServlet { 

    @PersistenceUnit 
    private EntityManagerFactory emf; 

    protected void processRequest(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 

     EntityManager em = null; 
     try { 
      em = emf.createEntityManager(); 

      //query for all the persons in database 
      List persons = em.createQuery("select u from Users u").getResultList(); 
      request.setAttribute("usersList",persons); 

      //Forward to the jsp page for rendering 
      request.getRequestDispatcher("UsersList.jsp").forward(request, response); 
     } catch (Exception ex) { 
      throw new ServletException(ex); 
     } finally { 
      //close the em to release any resources held up by the persistebce provider 
      if(em != null) { 
       em.close(); 
      } 
     } 
     response.setContentType("text/html;charset=UTF-8"); 
    }

但我看到NPE時嘗試emf.createEntityManager(); 我persistance.xml：

<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"> 
    <persistence-unit name="AdressBookPU"> 
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
    <jta-data-source>jdbc/__adressbook</jta-data-source> 
    <class>com.prokopenko.adressbook.entity.Users</class> 
    <class>com.prokopenko.adressbook.entity.MobilePhone</class> 
    </persistence-unit> 
</persistence>

它是一個Maven項目和persistance.xml位於的src/main /資源/ META-INF（如j2ee7教程）。 UPDATE 嘗試：

@PersistenceContext(unitName = "AdressBookPU") 
private EntityManager em;

和

@PersistenceUnit(unitName="AdressBookPU") 
private EntityManagerFactory emf;

來源

2014-05-06 bearhunterUA

嘗試添加@PersistenceUnit（name =「AdressBookPU」）並且不通過EMF訪問。製作你的私有var EntityManager並直接使用。希望能幫助到你。 – onesixtyfourth

我更新我的問題。 NPE ... – bearhunterUA

是'UsersListServlet'注入還是隻是一個普通類？ – Priyesh

哪個容器您使用的？你有沒有在這個容器中定義你的jta-data-source（jdbc/__ adressbook）？

來源

2014-05-06 15:00:57

是的，我發現問題在Tomcat和現在Im配置它，thx – bearhunterUA

PersistanceUnit註釋不注入

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