多对一关系

1.创建t_user表、t_group表

 

2.在eclipse中创建对应的实体类

1 package com.eneity; 2  3 public class User { 4      5     private int id; 6     private String name; 7     private Group group;//注意这里不是gid 而是group对象 8      9     public User() {10         super();11         // TODO Auto-generated constructor stub12     }13     public int getId() {14         return id;15     }16     public void setId(int id) {17         this.id = id;18     }19     public String getName() {20         return name;21     }22     public void setName(String name) {23         this.name = name;24     }25     public Group getGroup() {26         return group;27     }28     public void setGroup(Group group) {29         this.group = group;30     }31     32 33 }

1 package com.eneity; 2  3 public class Group { 4      5     private int id ; 6     private String name; 7      8     public Group() { 9         super();10         // TODO Auto-generated constructor stub11     }12     public int getId() {13         return id;14     }15     public void setId(int id) {16         this.id = id;17     }18     public String getName() {19         return name;20     }21     public void setName(String name) {22         this.name = name;23     }24 25 }

3.写对应的xml映射文件

注意：写好对应的xml文件后要在主配置文件中添加映射

1 
       2  4 
       5 
      
        6     
       
         7         
        
          8             
          9             
         10         
        11         
        
         12             
         13         
        14         
        
         15             
         16         
        17     
       18 
      

1 
       2  4 
       5 
      
        6     
       
         7         
        
          8             
          9             
         10         
        11         
        
         12             
         13         
        14     
       15 
      

主配置文件

1 
       2  5 
      
        6     
       
         7         
        
         com.mysql.jdbc.Driver
         8         
        
         xzt521
         9         
        
         jdbc:mysql://127.0.0.1:3306/myweb
        10         
        
         xzt
        11             
        12         
        
         true
        13         
        14         
        
         true
        15         
        16         
        17     
       18 
      

4.写一个测试类

注意：如果只是要查询数据，只要开启session即可

要增删改的话，要开启事务管理

最后要提交事务（这样数据库中才会存进去数据）

关闭session

1 package com.test; 2  3 import org.hibernate.Session; 4 import org.hibernate.SessionFactory; 5 import org.hibernate.Transaction; 6 import org.hibernate.cfg.Configuration; 7 import org.junit.After; 8 import org.junit.Before; 9 import org.junit.Test;10 11 import com.eneity.Customers;12 import com.eneity.Group;13 import com.eneity.Order;14 import com.eneity.User;15 16 17 public class Test1 {18     private SessionFactory buildSessionFactory;19     private Session Session;20     private Transaction Transaction;21 22     @Before23     public void before() {24         Configuration cfg = new Configuration().configure();25         buildSessionFactory = cfg.buildSessionFactory();26         Session = buildSessionFactory.openSession();27         Transaction = Session.beginTransaction();28         System.out.println(Session);29         30         31     }32     33     @Test34     public void test1() {35         // TODO Auto-generated method stub36         37         Group group = new Group();38         group.setName("duhao");39         User user = new User();40         user.setName("jiunan");41         user.setGroup(group);42         Session.save(group);43         Session.save(user);44         45 46     }47     48     @After49     public void after() {50         Transaction.commit();51         Session.close();52         53     }54 }