Hibernate：ManyToMany逆删除

我在两个表之间有一个ManyToMany关系，User和Keyword . 用户是该关系的所有者 . 如果我删除用户，我会先删除此用户的所有关键字，然后删除用户 . 这按预期工作 .

但我不知道如何删除关键字并自动删除与所有用户的关系 .

到目前为止，这是我的代码 .

@Entity
    @Table(name = "user")

    public class User {

      @Id
      @Column(name = "id")
      @GeneratedValue
      private Integer id;

      @Column(name = "name")
      private String name;

      @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
      @Fetch(value = FetchMode.SUBSELECT)
      @JoinTable(name = "user_has_keyword", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "keyword_id"))
      private List keywords = new ArrayList();

      // Getters and setters
      ...
    }

@Entity
    @Table(name = "keyword")
    public class Keyword {

      @Id
      @Column(name = "id")
      @GeneratedValue
      private Integer id;

      @Column(name = "keyword")
      private String keyword;

      @ManyToMany(mappedBy = "keywords")
      private List users = new ArrayList();

      // Getters and setters
      ...
    }

@Service("myService")
    @Transactional("transactionManager")
    public class MyService {

      @Resource(name = "sessionFactory")
      private SessionFactory sessionFactory;

      @SuppressWarnings("unchecked")
      public List getAllUsers() {
        Session session = this.sessionFactory.getCurrentSession();

        Query query = session.createQuery("FROM User");

        return query.list();
      }

      public User getUser(Integer id) {
        Session session = this.sessionFactory.getCurrentSession();
        return (User) session.get(User.class, id);
      }

      public void addUser(User user) {
        Session session = this.sessionFactory.getCurrentSession();
        session.save(user);
      }

      public void deleteUser(User user) {
        Session session = this.sessionFactory.getCurrentSession();

        // 1st, delete relations
        user.getKeywords().clear();
        session.update(user);

        // 2nd, delete User object
        session.delete(user);
      }

      public Keyword getKeyword(Integer id) {
        Session session = this.sessionFactory.getCurrentSession();
        return (Keyword) session.get(Keyword.class, id);
      }

      public Keyword addKeyword(Keyword keyword) {
        Session session = this.sessionFactory.getCurrentSession();
        session.save(keyword);

        return keyword;
      }

      public void deleteKeyword(Keyword keyword) {
        Session session = this.sessionFactory.getCurrentSession();

        // 1st, delete relations
        keyword.getUsers().clear();
        session.update(keyword);

        // 2nd, delete User object
        keyword = getKeyword(keyword.getId());
        session.delete(keyword);
      }
    }

@Controller
    public class MyController {

      @Resource(name = "myService")
      private MyService myService;

      @RequestMapping(value = "/add", method = RequestMethod.GET)
      public String add(Model model) {

        Keyword k = new Keyword();
        k.setKeyword("yellow");
        k = myService.addKeyword(k);

        User u1 = new User();
        u1.setName("Bart");
        u1.getKeywords().add(k);
        myService.addUser(u1);

        User u2 = new User();
        u2.setName("Lisa");
        u2.getKeywords().add(k);
        myService.addUser(u2);

        return "/";
      }

      @RequestMapping(value = "/delete/user", method = RequestMethod.GET)
      public String deleteUser(Model model) {

        User u = myService.getUser(1);
        myService.deleteUser(u);

        return "/";
      }

      @RequestMapping(value = "/delete/keyword", method = RequestMethod.GET)
      public String deleteKeyword(Model model) {

        Keyword k = myService.getKeyword(1);
        myService.deleteKeyword(k);

        return "/";
      }

    }

如果我浏览到/ delete / keyword，我会得到以下异常：

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.blabla.prototype.Keyword.users, no session or session was closed

我用谷歌搜索并尝试了许多不同的东西，但没有任何作用 .

我感谢任何帮助 .

非常感谢你，

马尔科