多对一：比如多个订单对应同一个用户，需要在订单表中添加一个用户的属性
订单类：
private Integer orderId; private Date createTime; private User user;
用户类：
private int userId; private String userName; private String userPsw;
一的方配置xml（user）：
<?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>
<class name="ni.jun.yang.bean.User" table="t_user">
<id name="userId">
<!-- 主键自动增长 -->
<generator class="native"></generator>
</id>
<property name="userName"></property>
<property name="userPsw"></property>
</class>
</hibernate-mapping>
多的一方配置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>
<class name="ni.jun.yang.bean.Orders" table="t_order">
<id name="orderId" column="orderId">
<generator class="native"></generator>
</id>
<property name="createTime" type="date"></property>
<!-- 多个订单对应一个用户，配置多对一的映射 cascade级联-->
<many-to-one name="user" class="ni.jun.yang.bean.User" column="userId" cascade="all">
</many-to-one>
</class>
</hibernate-mapping>
<many-to-one name="user" class="ni.jun.yang.bean.User" column="userId" cascade="all"> name：类中的成员变量名字class：对应类的全路径，配了包名只需要写类名即可column:数据库里面的字段名字cascade：级联 其值有“all”，“save-update”,“delete”等测试代码：由于配置级联 cascade=‘all’，保存订单会首先自动保存级联的用户对象
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction ts = session.beginTransaction();
User user = new User();
user.setUserName("不知3");
user.setUserPsw("4563");
Orders orders1 =new Orders();
orders1.setCreateTime(new Date());
orders1.setUser(user);
session.save(orders1);
ts.commit();
session.close();
一对多：比如一个人可以有多张银行卡
一的一方需要设置一个 集合来存放多的一方 使用list 或者set集合，一般多用set集合
如：一个人有多个地址，list集合存放
private List<String> addresses;
xml配置：list用list标签，要配置索引 list-index
<list name="addresses" table="address">
<key column="customerId"></key>
<!-- 用list需要配list索引，相当于下标从0开始 -->
<list-index column="ListIndex"></list-index>
<element type="string" column="addressName"></element>
</list>
set集合存放：
private Set<String> addresses;
xml配置：set用set标签
<set name="addresses" table="address" sort="natural">
<key column="customerId"></key>
<element type="string" column="addressName"></element>
</set>
双向一对多：如一个人有多套房，他就有多个地址
customer：
private Integer customerId;
private String customerName;
private Set<Address> adresses;
address：
private Customer customer;
private Integer addressId;
private String address;
customer xml配置：
<!-- inverse=true 放弃关联关系维护，默认false，关系维护-->
<set name="adresses" table="_Address" inverse="true" cascade="save-update">
<key column="customerId"></key>
<one-to-many class="ni.jun.yang.bean.Address" />
</set>
address xml配置
<many-to-one name="customer" class="Customer" column="customerId"></many-to-one>
测试代码：
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction ts = session.beginTransaction();
Address address1 = new Address();
address1.setAddress("青羊区");
Address address2 = new Address();
address2.setAddress("武侯区");
Set<Address> set = new HashSet<Address>();
set.add(address1);
set.add(address2);
Customer customer = new Customer();
customer.setCustomerName("zhubajie");
customer.setAdresses(set);
session.save(customer);
ts.commit();
session.close();
多对多，需要第三张表来建立关联关系，必须有一方放弃关联关系维护
类里面两边互相有对方作为成员变量
items：
private Set<Orders> orders=new HashSet<Orders>();
orders：
private Set<Items> items = new HashSet<>();
xml配置里面要设置第三张表来关联：orders_r_items 第三张表
items xml：
<set name="orders" table="orders_r_items">
<key column="itemsId"></key>
<many-to-many class="Orders" column="orderId"></many-to-many>
</set>
orders xml：
<!-- items的集合 多对多，必须有一方放弃关联关系维护 -->
<set name="items" table="orders_r_items" inverse="true">
<key column="orderId"></key>
<many-to-many class="Items" column="itemsId"></many-to-many>
</set>
测试代码：
Session session = HibernateUtil.getSession();
Transaction tx = session.beginTransaction();
Items item = new Items();
item.setPrice(new Double(100));
Items item1 = new Items();
item1.setPrice(new Double(200));
Orders o = new Orders();
o.setCreateTime(new Date());
Orders o1 = new Orders();
o1.setCreateTime(new Date());
o.getItems().add(item);
o.getItems().add(item1);
o1.getItems().add(item);
o1.getItems().add(item1);
item.getOrders().add(o);
item.getOrders().add(o1);
item1.getOrders().add(o);
item1.getOrders().add(o1);
session.save(item);
session.save(item1);
session.save(o);
session.save(o1);
tx.commit();
session.close();
来源：https://www.cnblogs.com/nijunyang/p/7666243.html