Hibernate多对多双向关联(Annotation配置)

Hibernate多对多双向关联(Annotation配置)

Role.java

package  com.many2many.bean;

import  java.util.Set;

import  javax.persistence.CascadeType;
import  javax.persistence.Column;
import  javax.persistence.Entity;
import  javax.persistence.GeneratedValue;
import  javax.persistence.GenerationType;
import  javax.persistence.Id;
import  javax.persistence.ManyToMany;
import  javax.persistence.Table;

@Entity
@Table(name = " roles " ,catalog = " Hibernate_Many2Many " )
public   class  Role {
    
     private   int  id;
     private  String name;
     private  Set < User >  users;
    @Id
    @Column(name = " id " )
    @GeneratedValue(strategy = GenerationType.AUTO)
     public   int  getId() {
         return  id;
    }
     public   void  setId( int  id) {
         this .id  =  id;
    }
    @Column(name = " name " )
     public  String getName() {
         return  name;
    }
     public   void  setName(String name) {
         this .name  =  name;
    }
    @ManyToMany(mappedBy = " roles " ,cascade = CascadeType.ALL)
     public  Set < User >  getUsers() {
         return  users;
    }
     public   void  setUsers(Set < User >  users) {
         this .users  =  users;
    }
    
}

User.java

package  com.many2many.bean;

import  java.util.Set;

import  javax.persistence.CascadeType;
import  javax.persistence.Column;
import  javax.persistence.Entity;
import  javax.persistence.GeneratedValue;
import  javax.persistence.GenerationType;
import  javax.persistence.Id;
import  javax.persistence.JoinColumn;
import  javax.persistence.JoinTable;
import  javax.persistence.ManyToMany;
import  javax.persistence.Table;

@Entity
@Table(name = " users " ,catalog = " Hibernate_Many2Many " )
public   class  User {
    
     private   int  id;
     private  String name;
     private  Set < Role >  roles;
    @Id
    @Column(name = " id " )
    @GeneratedValue(strategy = GenerationType.AUTO)
     public   int  getId() {
         return  id;
    }
     public   void  setId( int  id) {
         this .id  =  id;
    }
    @Column(name = " name " )
     public  String getName() {
         return  name;
    }
     public   void  setName(String name) {
         this .name  =  name;
    }
    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(
            name = " user_role " ,
            joinColumns = @JoinColumn(name = " user_id " ),
            inverseJoinColumns = @JoinColumn(name = " role_id " )
    )
     public  Set < Role >  getRoles() {
         return  roles;
    }
     public   void  setRoles(Set < Role >  roles) {
         this .roles  =  roles;
    }
    
}

导出的sql

create   table  Hibernate_Many2Many.roles (
        id  integer   not   null  auto_increment,
        name  varchar ( 255 ),
         primary   key  (id)
    )

     create   table  Hibernate_Many2Many.users (
        id  integer   not   null  auto_increment,
        name  varchar ( 255 ),
         primary   key  (id)
    )

     create   table  user_role (
         user_id   integer   not   null ,
        role_id  integer   not   null ,
         primary   key  ( user_id , role_id)
    )

     alter   table  user_role 
         add   index  FK143BF46ADA6B394F (role_id), 
         add   constraint  FK143BF46ADA6B394F 
         foreign   key  (role_id) 
         references  Hibernate_Many2Many.roles (id)

     alter   table  user_role 
         add   index  FK143BF46A7F95FD2F ( user_id ), 
         add   constraint  FK143BF46A7F95FD2F 
         foreign   key  ( user_id ) 
         references  Hibernate_Many2Many.users (id)

测试代码

@Test
     public   void  insert(){
        Session session = HibernateSessionFactory.getSession();
        Transaction transaction = session.beginTransaction();
         try  {
            transaction.begin();
            User user = new  User();
            user.setName( " 张三 " );
            
            Role role = new  Role();
            role.setName( " 管理员 " );
            Set < Role >  roles = new  HashSet < Role > ();
            roles.add(role);
            user.setRoles(roles);
            
            session.persist(user);
            
            transaction.commit();
        }  catch  (HibernateException e) {
            e.printStackTrace();
            transaction.rollback();
        }
    }
    
    
    @Test
     public   void  select(){
        Session session = HibernateSessionFactory.getSession();
        User user = (User) session.get(User. class ,  1 );
        System.out.println(user.getName());
        Set < Role >  roles = user.getRoles();
         for  (Iterator < Role >  iterator  =  roles.iterator(); iterator.hasNext();) {
            Role role  =  (Role) iterator.next();
            System.out.println(role.getName());
        }
    }