jsf-2 - 如何将对象保存到 JSF session 中

Question

我尝试将对象保存到 session 映射中，但它给了我一个异常

public class testclass {

public static void main(String[] args) throws IOException
{
   UserInfo ui = new UserInfo();
   UserLogin ul= new UserLogin();

   ui.setAdds("India");
   ui.setEId("someone@yahoo.com");
   ui.setFName("someone");
   ui.setLName("someone2");
   ui.setStatus("single");
   ul.setPswd("somename");
   ul.setUserId("121");
   ul.setUserinfo(ui);



   AnnotationConfiguration config = new AnnotationConfiguration();
   config.configure("hibernate.cfg.xml");
   //new  SchemaExport(config).create(true, true);
   SessionFactory factory = config.buildSessionFactory();
   Session session = factory.getCurrentSession();
   System.out.println("Session configured");
   session.beginTransaction();
   session.save(ul);
   System.out.println("object saved");
   Query q = session.createQuery("from UserLogin where UserId='121'");
   UserLogin user = (UserLogin)q.uniqueResult();

   if(user!=null)
   {

      ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
      Map<String, Object> sessionMap = externalContext.getSessionMap();
      sessionMap.put("User",user);
      UserLogin hd =  (UserLogin)sessionMap.get("User");
      System.out.println("the user id is "+hd.getUserId());  
    }
        session.getTransaction().commit();

异常(exception):

Exception in thread "main" java.lang.NullPointerException at BeanMngr.testclass.main(testclass.java:58) Java Result: 1 BUILD SUCCESSFUL (total time: 4 seconds)

这个问题是怎么引起的，我该如何解决？

Answer 1

如果要在 jsf session 中存储对象，请执行以下操作:

FacesContext.getCurrentInstance().getExternalContext().getSessionMap().put("yourKey", yourObject);

SessionMap 是一个 Map<String, Object>您可以在 get(Object key) 的帮助下访问您存储的对象方法。