java - 如何防止hibernate在多对多映射中插入一个表

Question

我正在创建用户配置文件，用户可以在其中输入他们的兴趣，其中兴趣是预定义的列表，用户无法从该列表中选择。

我有 User 和 Interest 表，主键分别为 userId 和 interestId。

             Table:User
-------------------------------------
        userId      userName
          1            aaaa
          2            bbbb
          3            cccc

和

           Table:Intrest
-------------------------------------
      interestId    interestName
          1            Sports
          2            Reading
          3            Music

多对多映射表

         Table:UserIntrest
-------------------------------------
        userId    interestId
          1            1
          1            2
          1            3

这是我的代码

用户.java

@Entity
public class User {
    @Id 
    @GeneratedValue(strategy=GenerationType.AUTO)
    private long userId;
    private String username;
    private String password;

    @ManyToMany(cascade=CascadeType.ALL)
    @JoinTable(
        name="UserIntrest",
        joinColumns={ @JoinColumn(name="userId",referencedColumnName="userId") },
        inverseJoinColumns={ @JoinColumn(name="intrestId", referencedColumnName="intrestId") }
        )
    private List<Intrest> intrestList;

    ----- Getters Setters -----

Intrest.java

@Entity
@Table(name="intrest")
public class Intrest {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int intrestId;
    private String intrestName;

    public Intrest(String name){
        this.intrestName = name;
    }
----- Getters & Setters -----

ActionClass.java

public class ActionClass extends ActionSupport {


    private User user;
    private List<String> intrestList;//for get list of intrest from jsp select tag
    private List<Intrest> intrestLst = new ArrayList<Intrest>();

    public String execute(){
        for(int i = 0;i<intrestList.size();i++){
            System.out.print(intrestLst.add(new Intrest(intrestList.get(i))));
        }
        user.setIntrestList(intrestLst);

        SessionFactory sf = new Configuration().configure().buildSessionFactory();
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        session.save(user);
        session.getTransaction().commit();


        return SUCCESS;
    }

    ----- Getters & Setters -----

所以当我运行它时，它会在用户表中插入用户，在兴趣表中选择兴趣并在用户兴趣表中映射

一切正常，但我不需要在兴趣表中插入兴趣，因为我已经插入了所需的兴趣。

Hibernate: insert into User (password, username) values (?, ?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into UserIntrest (userId, intrestId) values (?, ?)
Hibernate: insert into UserIntrest (userId, intrestId) values (?, ?)
Hibernate: insert into UserIntrest (userId, intrestId) values (?, ?)
Hibernate: insert into UserIntrest (userId, intrestId) values (?, ?)

我不想执行

Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)
Hibernate: insert into intrest (intrestName) values (?)

查询。

我为这个问题搜索了很多，但找不到任何解决方案。

Answer 1

问题不在 hibernate 中，而是你的代码..如果你正在做new Interest(..)， hibernate 会将它们持久化在数据库中，你应该这样做:

public class MyAction extends ActionSupport {
    private Long[] interestIds;

    public String execute() {

        // get interests with ids
        // set interests to user
        // save user

    }

}