数据关联映射分为：一对多、多对一，一对一，多对多。

cascade属性

• save-update：在执行保存和修改是进行级联操作

• delete：在执行删除时进行级联操作

• all：在所有情况下进行级联操作

• none：不进行级联操作（默认）

抓取策略

 

一对多、多对一

一对多、多对一持久化类设计// User类public class User {  private int id; private String name; private int age; private Set
 addressSet;  //get set method }//Address类public class Address {  private int id; private String address; private int tel; private User user;  //get set method }

address.hbm.xml
          
               
                  
                 
                
                
                
            
       
     

user.hbm.xml
           
               
                  
                 
                
                
                
                
                  
                   
                 
            
        
     

一对一

持久化类设计public class Person {  private int id; private String userName; private Card card;  //get set Method } public class Card {  private int id; private String cardNum; private Person person;  //get set Method }

person.hbm.xml
          
               
                  
                 
                 
                  
           
       
     

多对多

ublic class Teacher {  private int id; private String name; private Set
     
       student;  //get set method } public class Student {  private int id; private String name; private Set
      
        teacher;  //get set method }
      
     

teacher.hbm.xml
          
               
                  
                 
                  
                
                  
                   
                 
        
            
       
     

student.hbm.xml
          
               
                  
                 
                
                
                    
                     
       
      
     

多对多一方要放弃关系维护
      
       排序
        延迟加载关闭 ： lazy="false"