Hibernate--多对多关系的表达、配置与操作(保存、修改、删除)详解

Myth丶恋晨 2021-08-14 02:20 376阅读 0赞

#### 创建表 ####

创建sys\_user、sys\_role、sys\_user\_role三张表：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

#### 创建实体 ####

**User：**

public class User { 
    	//主键
    	private Long user_id;
    	private String user_code;
    	private String user_name;
    	private String user_password;
    	private Character user_state;
    	
    	//表达多对多
    	private Set<Role> roles = new HashSet<Role>();
    	
    	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 Character getUser_state() { 
    		return user_state;
    	}
    	public void setUser_state(Character user_state) { 
    		this.user_state = user_state;
    	}
    	public Set<Role> getRoles() { 
    		return roles;
    	}
    	public void setRoles(Set<Role> roles) { 
    		this.roles = roles;
    	}
    }

**Role：**

//角色对象
    public class Role { 
    	//主键
    	private Long role_id;
    	private String role_name;
    	private String role_memo;
    	
    	//表达多对多
    	private Set<User> users = new HashSet<User>();
    	
    	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<User> getUsers() { 
    		return users;
    	}
    	public void setUsers(Set<User> users) { 
    		this.users = users;
    	}
    	
    }

#### 配置映射关系 ####

User.hbm.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping package="pers.zhang.domain" >
    	<class name="User" table="sys_user" >
    		<id name="user_id" >
    			<generator class="native"></generator>
    		</id>
    		<property name="user_code" ></property>
    		<property name="user_name" ></property>
    		<property name="user_password" ></property>
    		<property name="user_state" ></property>
    	
    		
    		
    		 
    		<set name="roles" table="sys_user_role" cascade="save-update" >
    			<key column="user_id" ></key>
    			<many-to-many class="Role" column="role_id" ></many-to-many>
    		</set>
    	
    	</class>
    </hibernate-mapping>

Role.hbm.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping package="pers.zhang.domain" >
    	<class name="Role" table="sys_role" >
    		<id name="role_id" >
    			<generator class="native"></generator>
    		</id>
    		<property name="role_name" ></property>
    		<property name="role_memo" ></property>
    
    				
    		<set name="users" table="sys_user_role" inverse="true" >
    			<key column="role_id" ></key>
    			<many-to-many class="User" column="user_id" ></many-to-many>
    		</set>
    	</class>
    </hibernate-mapping>

#### 操作 ####

**保存：**

@Test
    	//保存员工以及角色
    	public void fun1(){ 
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//-------------------------------------------------
    		//创建两个 User
    		User u1 = new User();
    		u1.setUser_name("小明");
    		
    		User u2 = new User();
    		u2.setUser_name("小黑");
    		
    		//创建两个 Role
    		Role r1 = new Role();
    		r1.setRole_name("保洁");
    		
    		Role r2 = new Role();
    		r2.setRole_name("保安");
    		//用户表达关系
    		u1.getRoles().add(r1);
    		u1.getRoles().add(r2);
    		
    		u2.getRoles().add(r1);
    		u2.getRoles().add(r2);
    		
    		//角色表达关系
    		r1.getUsers().add(u1);
    		r1.getUsers().add(u2);
    		
    		r2.getUsers().add(u1);
    		r2.getUsers().add(u2);
    		
    		//调用Save方法一次保存
    		session.save(u1);
    		session.save(u2);
    		session.save(r1);
    		session.save(r2);
    		//-------------------------------------------------
    		tx.commit();
    		session.close();
    	}

![在这里插入图片描述][20191006213434150.png]![在这里插入图片描述][20191006213445489.png]

![在这里插入图片描述][20191006213500602.png]

**更新：**

@Test
    	//为小明新增一个角色
    	public void fun3(){ 
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//-------------------------------------------------
    		//获得用户，小明
    		User user = session.get(User.class, 4l);
    		//创建角色
    		Role r = new Role();
    		r.setRole_name("食堂阿姨");
    		//将角色添加到用户中
    		user.getRoles().add(r);
    		//将角色转换为持久化
    		session.save(r);
    		//-------------------------------------------------
    		tx.commit();
    		session.close();
    	}

![在这里插入图片描述][20191006214428687.png]  
![在这里插入图片描述][20191006214442740.png]

**删除：**

@Test
    	//为小明解除角色
    	public void fun4(){ 
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//-------------------------------------------------
    		//获得用户，小明
    		User user = session.get(User.class, 4l);
    		//获得要操作的角色对象(保洁,保安)
    		Role r1 = session.get(Role.class, 3l);
    		Role r2 = session.get(Role.class, 4l);
    		//将角色从用户的角色集合中移除
    		user.getRoles().remove(r1);
    		user.getRoles().remove(r2);
    		
    		//-------------------------------------------------
    		tx.commit();
    		session.close();
    	}

![在这里插入图片描述][2019100621470597.png]  
![在这里插入图片描述][20191006214716188.png]  
![在这里插入图片描述][20191006214653277.png]

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[20191006213434150.png]: https://img-blog.csdnimg.cn/20191006213434150.png
[20191006213445489.png]: /images/20210813/50aeac289fe9467f9ac226135459dc1f.png
[20191006213500602.png]: /images/20210813/294e4b3ad626454a828d4e1388c6d654.png
[20191006214428687.png]: /images/20210813/5f80ee529961487eb0ba96cf017c37cc.png
[20191006214442740.png]: /images/20210813/6e94265ebcf54846adf95ea49d4bd558.png
[2019100621470597.png]: /images/20210813/9cd6383025764d708d05537adc80cdbf.png
[20191006214716188.png]: /images/20210813/3041c596aca44adbacd8c37590d12be0.png
[20191006214653277.png]: /images/20210813/fc1ccee620224f85910322453bc9fdf0.png