jakarta ee java createNamedQuery实体管理器和持久性

Question

我在java中收到这个错误消息

你们有谁知道我该怎么解决这个问题吗

HTTP Status 500 - Filter execution threw an exception

键入Exception report

消息Filter execution threw an exception

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

例外情况

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.

userdoimpl

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

看起来你调用的方法的参数是它不接受的。如果你给我们看源代码，我们会更有帮助

Answer 2

正在使用的实现似乎是JPA1实现。作为带有此签名的documented方法

TypedQuery createNamedQuery(String name, Class resultClass)

是在JPA2.0中引入的。可能的解决办法是：

1. 升级到JPA 2.0实施或
2. 改用createNamedQuery(java.lang.String name)并转换结果

Answer 3

请问“所有电影院”在哪里

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

希望这有帮助