Hibernate 一对多关系的实现

实体类User

 

public class User {
 private int uid;
 private String username;
 private String password;
 private Set<Order> orders;
}//省略构造和getter setter

 
 
实体类 Order
 

public class Order {
 private int orderid;
 private String name;
 private double balance;
 private User user;
}//省略构造和getter setter

  
映射文件 order.hbm.xml
 

<hibernate-mapping package="tc.day3.onetomany.entity">
 <class name="Order" table="ectsorder">
  <id name="orderid" >
   <generator class="native"></generator> <!--此处不可以不写,我一晚上时间才找出来-->
  </id>
  <property name="name"></property>
  <property name="balance"></property>
  <!-- user是Order类中的属性名order
  cascade是代表关联关系  column 是指外键 -->
  <many-to-one name="user" cascade="all" column="userid"></many-to-one>
 </class>
</hibernate-mapping>

  
 
映射文件 user.hbm.xml
 

<class name="User" table="ectsuser">
 <id name="uid" column="userid">
  <generator class="native"></generator>   
 </id>
 <property name="username"></property>
 <property name="password"></property>
 <!-- set是代表保存orders所在的集合 -->
 <set name="orders" cascade="all">
 <!-- userid代表在order表中的外键名 -->
  <key column="userid"></key>
  <!-- 映射的多方的类名，若不加包名则为全类名 -->
  <one-to-many class="Order"/>
 </set>
 

 
 

</class>
</hibernate-mapping>

  
 测试代码

public class Test {
 public static void main(String[] args) {
  Session session=DBFactory.getSession();
  Transaction ts=session.beginTransaction();
  try{
  Order order1=new Order();
  order1.setName("Java");
  order1.setBalance(99.5);
  Order order2=new Order();
  order2.setName("C++");
  order2.setBalance(78.5);
  Order order3=new Order();
  order3.setName("JDBC");
  order3.setBalance(96.5);
  User user=new User();
  user.setUsername("zhangsan");
  user.setPassword("123456");
  Set<Order> orders=new HashSet<Order>();
  order1.setUser(user);
  order2.setUser(user);
  order3.setUser(user);
  orders.add(order1);
  orders.add(order2);
  orders.add(order3);
  user.setOrders(orders);
  session.save(user);
  ts.commit();
  
  }catch(Exception e){
   e.printStackTrace();
   ts.rollback();
  }finally{
   session.close();
  }
  
 }


}