java createNamedQuery - 实体管理器和持久性

Question

我在java中收到此错误消息。

你们有没有人知道我该如何解决这个问题？

HTTP Status 500 - Filter execution threw an exception

类型Exception report

消息Filter execution threw an exception

描述The server encountered an internal error that prevented it from fulfilling this request.

例外

javax.servlet.ServletException: Filter execution threw an exception 
root cause 

java.lang.Error: Unresolved compilation problem: 
The method createNamedQuery(String) in the type EntityManager is not applicable for the arguments (String, Class<User>) 

bg.tu_sofia.cinema.dao.UserDAOImpl.getAllUsers(UserDAOImpl.java:22) 
bg.tu_sofia.cinema.dao.UserDAOImpl.usernameExists(UserDAOImpl.java:52) 
bg.tu_sofia.cinema.filters.UserReconcilerFilter.doFilter(UserReconcilerFilter.java:54) 
note The full stack trace of the root cause is available in the SAP logs. 

userDOAImpl

package bg.tu_sofia.cinema.dao; 

import java.util.List; 

import javax.persistence.EntityManager; 

import bg.tu_sofia.cinema.entities.Cinema; 
import bg.tu_sofia.utils.EntityManagerUtils; 

public class CinemaDAOImpl implements CinemaDAO { 

    private EntityManager em; 
    private EntityManagerUtils dbUtils; 

    public CinemaDAOImpl() { 
     this.dbUtils = EntityManagerUtils.getInstance(); 
     this.em = dbUtils.getEntityManagerInstance(); 
    } 

    public List<Cinema> getAllCinemas() { 
     return em.createNamedQuery("AllCinemas", Cinema.class).getResultList(); 
    } 

    public Cinema getCinemaByID(long id) { 
     return em.find(Cinema.class, id); 
    } 

    public void addCinema(Cinema cinema) { 
     dbUtils.startTransaction(em); 
     em.persist(cinema); 
     dbUtils.commitTransaction(em); 
    } 

    public void removeCinema(Cinema cinema) { 
     //TODO : don't forget when removing a cinema to remove all its related screenings. 
     dbUtils.startTransaction(em); 
     em.remove(cinema); 
     dbUtils.commitTransaction(em); 
    } 

    public void removeCinemaByID(long removalID) { 
     removeCinema(getCinemaByID(removalID)); 
    } 

} 

Answer 1

它看起来像你调用它不接受参数的方法。如果您向我们展示源代码，我们会更有帮助。

Answer 2

NamedQuery“AllCinemas”在哪里？

一个环节： http://web.securityinnovation.com/appsec-weekly/blog/bid/69739/Use-Named-Queries-with-Java-Persistence-API-JPA

希望这有助于

Answer 3

在使用中实现似乎是JPA 1日实施。如documented与此签名方法

TypedQuery createNamedQuery（字符串名称，类resultClass）

在JPA 2.0中引入的。可能的解决方案是：

1. 升级到JPA 2.0实现或使用createNamedQuery(java.lang.String name)代替铸造结果
2. 。