Hibernate集合映射之List

使用List和Map有很多共性，比如说不能再1方设置inverse="true"

不同的是，list可以保留元素的顺序，这个使通过一个idx字段来实现的，比如说Team和Student的1对多关系，我们给team加入学生的时候，需要记录加入的顺序，这时候我们可以使用list方式，并在student表中新增加一个idx字段（但在Student实体类中不定义idx属性） 

数据库结构：

 

create   table  teamList (id  varchar ( 32 ),teamname  varchar ( 32 ));
create   table  studentList (id  varchar ( 32 ),cardid  varchar ( 32 ),name  varchar ( 32 ),age  int ,description  varchar ( 32 ), team_id  varchar ( 32 ),idx  int );

 

POJO

 

package  Collection.List;

import  java.util.ArrayList;
import  java.util.List;
import  java.util.Map;

public   class  Team  ... {
   private String id;
   private String teamname;
   private List students=new ArrayList();
public String getId() ...{
    return id;
}
public void setId(String id) ...{
    this.id = id;
}
public String getTeamname() ...{
    return teamname;
}
public void setTeamname(String teamname) ...{
    this.teamname = teamname;
}
public List getStudents() ...{
    return students;
}
public void setStudents(List students) ...{
    this.students = students;
}

}



package  Collection.List;

public   class  Student  ... {
  private String id;
  private String name;
  private String description;
  private int age;
  private String cardid;
  private Team team;
public String getId() ...{
    return id;
}
public void setId(String id) ...{
    this.id = id;
}
public String getName() ...{
    return name;
}
public void setName(String name) ...{
    this.name = name;
}
public String getDescription() ...{
    return description;
}
public void setDescription(String description) ...{
    this.description = description;
}
public int getAge() ...{
    return age;
}
public void setAge(int age) ...{
    this.age = age;
}
public String getCardid() ...{
    return cardid;
}
public void setCardid(String cardid) ...{
    this.cardid = cardid;
}
public Team getTeam() ...{
    return team;
}
public void setTeam(Team team) ...{
    this.team = team;
}
}

 

Team.hbm.xml

 

<? xml version="1.0" encoding="utf-8" ?>
<! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<!--  
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class  name ="Collection.List.Team"  table ="teamList"   >
     < id  name ="id"  unsaved-value ="null" >
       < generator  class ="uuid.hex" ></ generator >
     </ id >
     < property  name ="teamname"  type ="string"  column ="teamname" ></ property >
     <!-- 由于index需要team来维护，所以，使用list表示1对多时候，不能再1方设置inverse="true" -->
     < list  name ="students"  table ="studentList"  cascade ="all"   >
       < key  column ="team_id" ></ key >
       <!--  index代表key,element(或one-to-many)代表value -->
       <!--  这里用cardid作为key,具体的student实例作为value  -->
       < index  column ="idx"  type ="int" ></ index >
       < one-to-many  class ="Collection.List.Student" />
     </ list >
</ class >

</ hibernate-mapping >

 

Student.hbm.xml

 

<? xml version="1.0" encoding="utf-8" ?>
<! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<!--  
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class  name ="Collection.List.Student"  table ="studentList"   >
     < id  name ="id"  unsaved-value ="null" >
       < generator  class ="uuid.hex" ></ generator >
     </ id >
     < property  name ="cardid"  type ="string"  column ="cardid" ></ property >
     < property  name ="name"  type ="string"  column ="name" ></ property >
     < property  name ="age"  type ="int"  column ="age" ></ property >
     < property  name ="description"  type ="string"  column ="description" ></ property >  
     < many-to-one  name ="team"  
                 column ="team_id"
                 class ="Collection.List.Team"  
                 cascade ="none"  
                 fetch ="join" >
     </ many-to-one >
</ class >

</ hibernate-mapping >

 

Hibernate.cfg.xml

 

<? xml version='1.0' encoding='UTF-8' ?>
<! DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >

<!--  Generated by MyEclipse Hibernate Tools.                    -->
< hibernate-configuration >

< session-factory >
     < property  name ="connection.username" > root </ property >
     < property  name ="connection.url" >
        jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312 &amp; useUnicode=true
     </ property >
     < property  name ="dialect" >
        org.hibernate.dialect.MySQLDialect
     </ property >
     < property  name ="myeclipse.connection.profile" > mysql </ property >
     < property  name ="connection.password" > 1234 </ property >
     < property  name ="connection.driver_class" >
        com.mysql.jdbc.Driver
     </ property >
     < property  name ="hibernate.dialect" >
        org.hibernate.dialect.MySQLDialect
     </ property >
     < property  name ="hibernate.show_sql" > true </ property >
     < property  name ="current_session_context_class" > thread </ property >
     < property  name ="jdbc.batch_size" > 15 </ property >
     < mapping  resource ="Collection/List/Student.hbm.xml"   />
     < mapping  resource ="Collection/List/Team.hbm.xml"   />




</ session-factory >

</ hibernate-configuration >

 

测试代码：

 

package  Collection.List;


import  java.io.File;
import  java.util.Map;

import  org.hibernate.Session;
import  org.hibernate.SessionFactory;
import  org.hibernate.Transaction;
import  org.hibernate.cfg.Configuration;

public   class  Test  ... {


    public static void main(String[] args) ...{

        String filePath=System.getProperty("user.dir")+File.separator+"src/Collection/List"+File.separator+"hibernate.cfg.xml";
        File file=new File(filePath);
        System.out.println(filePath);
        SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();
        Session session=sessionFactory.openSession();
        Transaction t=session.beginTransaction();
        
    
        
        Team team1=new Team();
        team1.setTeamname("team1");
        
        Team team2=new Team();
        team2.setTeamname("team2");
        
       
        Student stu1=new Student();
        stu1.setAge(11);
        stu1.setName("tom1");
        stu1.setCardid("11111");
        stu1.setDescription("tom1 description");
        
        Student stu2=new Student();
        stu2.setAge(22);
        stu2.setName("tom2");
        stu2.setCardid("22222");
        stu2.setDescription("tom2 description");
        
        Student stu3=new Student();
        stu3.setAge(33);
        stu3.setName("tom3");
        stu3.setCardid("33333");
        stu3.setDescription("tom3 description");
        
        Student stu4=new Student();
        stu4.setAge(44);
        stu4.setName("tom4");
        stu4.setCardid("55555");
        stu4.setDescription("tom4 description");
        
        team1.getStudents().add(stu1);
        team1.getStudents().add(stu3);
        team2.getStudents().add(stu2);
        team2.getStudents().add(stu4);
        
        session.save(team1);
        session.save(team2);
        t.commit();
        
    }

}

 

运行结果：

Hibernate: insert into teamList (teamname, id) values (?, ?)
Hibernate: insert into studentList (cardid, name, age, description, team_id, id) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into studentList (cardid, name, age, description, team_id, id) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into teamList (teamname, id) values (?, ?)
Hibernate: insert into studentList (cardid, name, age, description, team_id, id) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into studentList (cardid, name, age, description, team_id, id) values (?, ?, ?, ?, ?, ?)
Hibernate: update studentList set team_id=?, idx=? where id=?
Hibernate: update studentList set team_id=?, idx=? where id=?
Hibernate: update studentList set team_id=?, idx=? where id=?
Hibernate: update studentList set team_id=?, idx=? where id=?