hibernate基础（六）--多对多关联映射
hibernate的多对多关联映射
以用户和角色为例
创建用户实体
package cn.imau.entity;
import java.util.HashSet;
import java.util.Set;
public class User {
private Long user_id;
private String user_code;
private String user_name;
private String user_password;
private String user_state;
//用户所属的角色的集合
private Set roles=new HashSet();
public Long getUser_id() {
return user_id;
}
public void setUser_id(Long user_id) {
this.user_id = user_id;
}
public String getUser_code() {
return user_code;
}
public void setUser_code(String user_code) {
this.user_code = user_code;
}
public String getUser_name() {
return user_name;
}
public void setUser_name(String user_name) {
this.user_name = user_name;
}
public String getUser_password() {
return user_password;
}
public void setUser_password(String user_password) {
this.user_password = user_password;
}
public String getUser_state() {
return user_state;
}
public void setUser_state(String user_state) {
this.user_state = user_state;
}
public Set getRoles() {
return roles;
}
public void setRoles(Set roles) {
this.roles = roles;
}
}
创建角色实体
package cn.imau.entity;
import java.util.HashSet;
import java.util.Set;
public class Role {
private Long role_id;
private String role_name;
private String role_memo;
//一个角色包含多个用户
private Set users=new HashSet();
public Long getRole_id() {
return role_id;
}
public void setRole_id(Long role_id) {
this.role_id = role_id;
}
public String getRole_name() {
return role_name;
}
public void setRole_name(String role_name) {
this.role_name = role_name;
}
public String getRole_memo() {
return role_memo;
}
public void setRole_memo(String role_memo) {
this.role_memo = role_memo;
}
public Set getUsers() {
return users;
}
public void setUsers(Set users) {
this.users = users;
}
}
用户映射
<hibernate-mapping package="cn.imau.entity">
<class name="User" table="sys_user">
<id name="user_id" >
<generator class="native">generator>
id>
<property name="user_code" />
<property name="user_name"/>
<property name="user_password" />
<property name="user_state"/>
<set name="roles" table="sys_user_role">
<key column="user_id" >key>
<many-to-many class="Role" column="role_id" >many-to-many>
set>
class>
hibernate-mapping>角色映射
<hibernate-mapping package="cn.imau.entity">
<class name="Role" table="sys_role">
<id name="role_id">
<generator class="native"/>
id>
<property name="role_name"/>
<property name="role_memo"/>
<set name="users" table="sys_user_role">
<key column="role_id">key>
<many-to-many class="User" column="user_id">
many-to-many>
set>
class>
hibernate-mapping>在核心配置文件中引入映射文件
<mapping resource="cn/imau/entity/User.hbm.xml" />
<mapping resource="cn/imau/entity/Role.hbm.xml" />编写测试类
package cn.imau.test;
import cn.imau.entity.User;
import cn.imau.entity.Role;
import cn.utils.HibernateUtils;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
public class test {
@Test
//保存用户和角色
public void demo1(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
User user1=new User();
user1.setUser_name("zhangsan");
User user2=new User();
user2.setUser_name("lisi");
Role role1=new Role();
role1.setRole_name("assistant");
Role role2=new Role();
role2.setRole_name("HR");
Role role3=new Role();
role3.setRole_name("Manager");
//如果多对多建立了双向关联，一定要有一方放弃外键维护权
user1.getRoles().add(role1);
user1.getRoles().add(role3);
user2.getRoles().add(role2);
user2.getRoles().add(role3);
role1.getUsers().add(user1);
role2.getUsers().add(user1);
role2.getUsers().add(user2);
role3.getUsers().add(user2);
session.save(user1);
session.save(user2);
session.save(role1);
session.save(role2);
session.save(role3);
transaction.commit();
}
}
多对多的相关操作
级联保存或更新
保存用户级联角色
配置映射
<set name="roles" table="sys_user_role" cascade="save-update">
<key column="user_id" >key>
to-many class="Role" column="role_id" > to-many>
set>编写测试代码
package cn.imau.test;
import cn.imau.entity.User;
import cn.imau.entity.Role;
import cn.utils.HibernateUtils;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
public class test {
@Test
/*
* 多对多只保存一边也是不可以的
* 配置级联：保存用户级联角色，在User.hbm.xml中上配置cascade="save-update"
* */
public void demo2(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
User user1=new User();
user1.setUser_name("zhangsan");
User user2=new User();
user2.setUser_name("lisi");
Role role1=new Role();
role1.setRole_name("assistant");
Role role2=new Role();
role2.setRole_name("HR");
Role role3=new Role();
role3.setRole_name("Manager");
//如果多对多建立了双向关联，一定要有一方放弃外键维护权
user1.getRoles().add(role1);
user1.getRoles().add(role3);
user2.getRoles().add(role2);
user2.getRoles().add(role3);
role1.getUsers().add(user1);
role2.getUsers().add(user1);
role2.getUsers().add(user2);
role3.getUsers().add(user2);
session.save(user1);
session.save(user2);
/* session.save(role1);
session.save(role2);
session.save(role3);*/
transaction.commit();
}
}
保存角色级联用户
配置映射
<set name="users" table="sys_user_role" cascade="save-update">
<key column="role_id">key>
to-many class="User" column="user_id">
to-many>
set>编写测试代码
package cn.imau.test;
import cn.imau.entity.User;
import cn.imau.entity.Role;
import cn.utils.HibernateUtils;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
public class test {
@Test
/*
* 多对多只保存一边也是不可以的
* 配置级联：保存角色级联用户，在Role.hbm.xml中上配置cascade="save-update"
* */
public void demo3(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
User user1=new User();
user1.setUser_name("zhangsan");
User user2=new User();
user2.setUser_name("lisi");
Role role1=new Role();
role1.setRole_name("assistant");
Role role2=new Role();
role2.setRole_name("HR");
Role role3=new Role();
role3.setRole_name("Manager");
//如果多对多建立了双向关联，一定要有一方放弃外键维护权
user1.getRoles().add(role1);
user1.getRoles().add(role3);
user2.getRoles().add(role2);
user2.getRoles().add(role3);
role1.getUsers().add(user1);
role2.getUsers().add(user1);
role2.getUsers().add(user2);
role3.getUsers().add(user2);
/*session.save(user1);
session.save(user2);*/
session.save(role1);
session.save(role2);
session.save(role3);
transaction.commit();
}
}
级联删除
删除用户级联角色
映射配置
<set name="roles" table="sys_user_role" cascade="delete,save-update">
<key column="user_id" >key>
to-many class="Role" column="role_id" > to-many>
set>编写测试代码
@Test
//级联删除：删除用户 级联删除角色
public void demo4(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
User user=session.get(User.class,1L);
session.delete(user);
transaction.commit();
}删除角色级联删除用户
映射配置
<set name="users" table="sys_user_role" cascade="delete,save-update">
<key column="role_id">key>
to-many class="User" column="user_id">
to-many>
set>编写测试代码
@Test
//级联删除：删除角色 级联删除用户
public void demo5(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
Role role=session.get(Role.class,3L);
session.delete(role);
transaction.commit();
}多对多的其他操作
删除某个用户的角色
@Test
//将2号用户中的1号角色去掉
public void demo6(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
//查询2号用户
User user =session.get(User.class,2L);
//查询1号角色
Role role=session.get(Role.class,1L);
//操作集合相当于操作中间表
user.getRoles().remove(role);
transaction.commit();
}将某个用户的角色改选
@Test
//将2号用户中的1号角色去掉,改为3号角色
public void demo7(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
//查询2号用户
User user =session.get(User.class,2L);
//查询1号角色
Role role1=session.get(Role.class,1L);
//查询3号角色
Role role3=session.get(Role.class,3L);
user.getRoles().remove(role1);
user.getRoles().add(role3);
transaction.commit();
}给某个用户添加新角色
@Test
//给1号用户添加2号角色
public void demo8(){
Session session= HibernateUtils.getCurrentSession();
Transaction transaction=session.beginTransaction();
//查询1号用户
User user =session.get(User.class,1L);
//查询2号角色
Role role=session.get(Role.class,2L);
user.getRoles().add(role);
transaction.commit();
}