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  • hibernate 之 关联映射的双向多对多关联映射

    1. 在实际开发中,多对多关联比较常见,比如用户和角色,

    或者角色和权限。角色和权限的关系:

    2. 类结构: Permission.java

    public class Permission {
        private int id;
        private String name;
        private Set<Role> roles;
        public Permission() {
            // TODO Auto-generated constructor stub
        }
        
        public Permission(String name) {
            super();
            this.name = name;
        }
    
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
    
        public Set<Role> getRoles() {
            return roles;
        }
    
        public void setRoles(Set<Role> roles) {
            this.roles = roles;
        }
    }

    Role.java

    public class Role {
        private int id;
        private String name;
        private Set<Permission> permissions=new HashSet<Permission>();
        public Role() {
            // TODO Auto-generated constructor stub
        }
        
        public Role(String name) {
            super();
            this.name = name;
        }
    
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public Set<Permission> getPermissions() {
            return permissions;
        }
        public void setPermissions(Set<Permission> permissions) {
            this.permissions = permissions;
        }
    }

    3. 映射文件: Permission.hbm.xml :

    <hibernate-mapping>
        <class name="cn.wh.vo.Permission" table="t_permission">
            <id name="id">
                <generator class="native"></generator>
            </id>
            <property name="name"/>
            <set name="roles" table="t_role_permission" inverse="true">
                <key column="pid"></key>
                <many-to-many column="rid" class="cn.sxt.vo.Role"></many-to-many>
            </set>
        </class>
    </hibernate-mapping>

    Role.hbm.xml

    <hibernate-mapping package="cn.wh.vo">
        <class name="Role" table="t_role">
            <id name="id">
                <generator class="native"></generator>
            </id>
            <property name="name"/>
            <!-- table表示 关联表  这张表由hibernate来创建和维护-->
            <set name="permissions" table="t_role_permission">
                <!-- 当前类在关联表中的外键 -->
                <key column="rid"></key>
                <!-- 表示当前类的关联类在关联表中的外键 -->
                <many-to-many column="pid" class="Permission"/>
            </set>
        </class>
    </hibernate-mapping>

    4. 测试:

    public class HibernateTest {
        private Session session=null;
        @Before
        public void setUp(){
            session = HibernateUtil.getSession();
        }
        @After
        public void tearDown(){
            HibernateUtil.close();
        }
        @Test
        public void testCreateDB(){
            Configuration cfg = new Configuration().configure();
            SchemaExport export = new SchemaExport(cfg);
            //第一个参数  是否打印  数据库脚本
            //第二个参数 是否将脚本导入数据库执行
            export.create(true, true);
        }
        @Test
        public void testInit(){
            Transaction tx = null;
            try {
                tx = session.beginTransaction();
                Role r1 = new Role("管理员");
                Role r2 = new Role("会员");
                Permission p1 = new Permission("系统管理");
                Permission p2 = new Permission("用户管理");
                Permission p3 = new Permission("订单管理");
                Permission p4 = new Permission("商品管理");
                r1.getPermissions().add(p1);
                r1.getPermissions().add(p2);
                r1.getPermissions().add(p3);
                r1.getPermissions().add(p4);
                r2.getPermissions().add(p3);
                r2.getPermissions().add(p4);
                session.save(p1);
                session.save(p2);
                session.save(p3);
                session.save(p4);
                session.save(r1);
                session.save(r2);
                tx.commit();
                
            } catch (Exception e) {
                if(tx!=null)
                    tx.rollback();
            }
        }
        @Test
        public void testGet(){
            Role r = (Role)session.get(Role.class, 1);
            System.out.println(r.getName());
            System.out.println("--------------");
            for(Permission p:r.getPermissions()){
                System.out.println(p.getName());
            }
            System.out.println("===============");
            Permission p = (Permission)session.get(Permission.class, 3);
            System.out.println(p.getName());
            for(Role r1:p.getRoles()){
                System.out.println(r1.getName());
            }
        }
    }

    publicclass HibernateTest {

       private Session session=null;

       @Before

       publicvoid setUp(){

          session = HibernateUtil.getSession();

       }

       @After

       publicvoid tearDown(){

          HibernateUtil.close();

       }

       @Test

       publicvoid testCreateDB(){

          Configuration cfg = new Configuration().configure();

          SchemaExport export = new SchemaExport(cfg);

          //第一个参数  是否打印  数据库脚本

          //第二个参数是否将脚本导入数据库执行

          export.create(true, true);

       }

       @Test

       publicvoid testInit(){

          Transaction tx = null;

          try {

             tx = session.beginTransaction();

             Role r1 = new Role("管理员");

             Role r2 = new Role("会员");

             Permission p1 = new Permission("系统管理");

             Permission p2 = new Permission("用户管理");

             Permission p3 = new Permission("订单管理");

             Permission p4 = new Permission("商品管理");

             r1.getPermissions().add(p1);

             r1.getPermissions().add(p2);

             r1.getPermissions().add(p3);

             r1.getPermissions().add(p4);

             r2.getPermissions().add(p3);

             r2.getPermissions().add(p4);

             session.save(p1);

             session.save(p2);

             session.save(p3);

             session.save(p4);

             session.save(r1);

             session.save(r2);

             tx.commit();

            

          } catch (Exception e) {

             if(tx!=null)

                tx.rollback();

          }

       }

       @Test

       publicvoid testGet(){

          Role r = (Role)session.get(Role.class, 1);

          System.out.println(r.getName());

          System.out.println("--------------");

          for(Permission p:r.getPermissions()){

             System.out.println(p.getName());

          }

          System.out.println("===============");

          Permission p = (Permission)session.get(Permission.class, 3);

          System.out.println(p.getName());

          for(Role r1:p.getRoles()){

             System.out.println(r1.getName());

          }

       }

    }

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  • 原文地址:https://www.cnblogs.com/forever2h/p/6737766.html
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