类集合包含的Hibernate映射

类集合包含的Hibernate映射

类集合包含意味着一个类中的成员变量是另一个类的集合,比如说公司类Company包含成员类Member的集合.

类图如下:


它们分别对应数据库中的Companys表和Members表,它们的ER图如下:

以下代码演示了如何将类与数据库映射起来:

Company类代码:

package  com.sitinspring.companymember;

import  java.util.HashSet;
import  java.util.Set;

public   class  Company {
    private long id;
    private String name;
    private Set<Member> members = new HashSet<Member>();    
    
    public Company(){
    }
    
    public Company(long id,String name){
        this.id=id;
        this.name=name;
    }
    
    public void add(Member member){
        member.setCid(id);
        members.add(member);
    }
    
    public String toString(){
        String retval="Company id="+id+" name="+name;
        
        for(Member member:members){
            retval+="\n"+member;
        }
        
        return retval;
    }
    
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    public Set<Member> getMembers() {
        return members;
    }

    public void setMembers(Set<Member> members) {
        this.members = members;
    }
}

Company.hbm.xml:

<? xml version="1.0" ?>
<! DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
< hibernate-mapping  package ="org.hibernate.auction" >
     < class  name ="com.sitinspring.companymember.Company"  table ="COMPANYS" >
         < id  name ="id"  column ="ID" />
         < property  name ="name"  column ="NAME"   />
        
         < set  name ="members"  inverse ="true"  cascade ="all"  lazy ="false" >
             < key  column ="CID"   />
             < one-to-many  class ="com.sitinspring.companymember.Member"   />
         </ set >
     </ class >
</ hibernate-mapping >

Member类代码:

package  com.sitinspring.companymember;

public   class  Member  {
    private long id;

    private long cid;

    private String name;

    public Member() {
    }
    
    public Member(long id, String name) {
        this.id = id;
        this.name = name;
    }
    
    public String toString(){
        return "Member id="+id+" cid="+cid+" name="+name;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public long getCid() {
        return cid;
    }

    public void setCid(long cid) {
        this.cid = cid;
    }
}

Member.hbm.xml:

<? xml version="1.0" ?>
<! DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
< hibernate-mapping  package ="org.hibernate.auction" >
     < class  name ="com.sitinspring.companymember.Member"  table ="MEMBERS" >
         < id  name ="id"  column ="ID" />
         < property  name ="cid"  column ="CID"   />
         < property  name ="name"  column ="NAME"   />
     </ class >
</ hibernate-mapping >

测试代码如下:

package  com.sitinspring.companymember;

import  org.hibernate.Session;

import  com.sitinspring.util.HibernateUtil;

public   class  Main  {
    public static void main(String[] args) {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        // --插入代码开始
        Company citi = new Company(1, "Citi");
        citi.add(new Member(10, "Andy"));
        citi.add(new Member(11, "Bill"));
        session.save(citi);

        Company google = new Company(2, "google");
        google.add(new Member(20, "Cindy"));
        google.add(new Member(21, "Dennis"));
        session.save(google);

        session.flush();

        Company company = (Company) session.load(Company.class, citi.getId());
        company = (Company) session.load(Company.class, google.getId());
        // --插入代码结束

        // --读取代码开始
        long i = 1;

        Company companyLoaded = (Company) session.load(Company.class, i);
        System.out.println(companyLoaded);
        i = 2;
        companyLoaded = (Company) session.load(Company.class, i);
        System.out.println(companyLoaded);
        // --读取代码开始

        session.getTransaction().commit();
        HibernateUtil.getSessionFactory().close();
    }
}

测试结果:




代码下载:
http://www.blogjava.net/Files/sitinspring/HibernateClasses20071109085612.rar