[SXT][WY]Hibernate11 其他映射

最新推荐文章于 2022-10-26 09:24:45 发布

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本文介绍Hibernate中使用component映射实体组件的方法及复合主键的配置方式。component映射能实现对象模型的细粒度划分，提高代码复用率。复合主键则通过组合多个字段作为主键，适用于多对多关系等场景。

component映射

在hibernate中,component是某个实体的逻辑组成部分，它与实体的根本区别是没有oid，
component可以成为是值对象（DDD）

采用component映射的好处：它实现了对象模型的细粒度划分，层次会更分明，复用率会更高

public class User {

private int id;

private String name;

private Contact contact;

}

public class Contact {

private String email;

private String address;

private String zipCode;

private String contactTel;

}

User.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>
<class name="com.bjsxt.hibernate.User" table="t_user">
  <id name="id">
   <generator class="native"/>
  </id>
  <property name="name"/>
  <component name="contact">
   <property name="email"/>
   <property name="address"/>
   <property name="zipCode"/>
   <property name="contactTel"/>
  </component>
</class>
</hibernate-mapping>

public void testSave1() {
  Session session = null;
  try {
   session = HibernateUtils.getSession();
   session.beginTransaction();

   User user = new User();
   user.setName("张三");

   Contact contact = new Contact();
   contact.setAddress("xxxxx");
   contact.setEmail("xxx@rrr.com");
   contact.setZipCode("1111111");
   contact.setContactTel("9999999999");

   user.setContact(contact);

   session.save(user);
   session.getTransaction().commit();
  }catch(Exception e) {
   e.printStackTrace();
   session.getTransaction().rollback();
  }finally {
   HibernateUtils.closeSession(session);
  }
}

复合（联合）主键映射

通常将复合主键相关的属性，单独放到一个类中
* 此类必须实现序列化接口
* 覆写hashcode和equals方法

public class FiscalYearPeriodPK implements Serializable {

//核算年
private int fiscalYear;

//核算月
private int fiscalPeriod;

@Override
public int hashCode() {
  final int prime = 31;
  int result = 1;
  result = prime * result + fiscalPeriod;
  result = prime * result + fiscalYear;
  return result;
}

@Override
public boolean equals(Object obj) {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  if (getClass() != obj.getClass())
   return false;
  final FiscalYearPeriodPK other = (FiscalYearPeriodPK) obj;
  if (fiscalPeriod != other.fiscalPeriod)
   return false;
  if (fiscalYear != other.fiscalYear)
   return false;
  return true;
}

}

public class FiscalYearPeriod {

private FiscalYearPeriodPK fiscalYearPeriodPK;

//开始日期
private Date beginDate;

//结束日期
private Date endDate;

//状态
private String periodSts;

}

<?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>
<class name="com.bjsxt.hibernate.FiscalYearPeriod" table="t_fiscal_year_period">
  <composite-id name="fiscalYearPeriodPK">
   <key-property name="fiscalYear"/>
   <key-property name="fiscalPeriod"/>
  </composite-id>
  <property name="beginDate"/>
  <property name="endDate"/>
  <property name="periodSts"/>
</class>
</hibernate-mapping>

public void testSave1() {
  Session session = null;
  try {
   session = HibernateUtils.getSession();
   session.beginTransaction();

   FiscalYearPeriod fiscalYearPeriod = new FiscalYearPeriod();

   FiscalYearPeriodPK pk = new FiscalYearPeriodPK();
   pk.setFiscalYear(2008);
   pk.setFiscalPeriod(8);

   fiscalYearPeriod.setFiscalYearPeriodPK(pk);

   fiscalYearPeriod.setBeginDate(new Date());
   fiscalYearPeriod.setEndDate(new Date());
   fiscalYearPeriod.setPeriodSts("Y");

   session.save(fiscalYearPeriod);
   session.getTransaction().commit();
  }catch(Exception e) {
   e.printStackTrace();
   session.getTransaction().rollback();
  }finally {
   HibernateUtils.closeSession(session);
  }
}

public void testLoad1() {
  Session session = null;
  try {
   session = HibernateUtils.getSession();
   session.beginTransaction();

   FiscalYearPeriodPK pk = new FiscalYearPeriodPK();
   pk.setFiscalYear(2008);
   pk.setFiscalPeriod(8);

   FiscalYearPeriod fiscalYearPeriod = (FiscalYearPeriod)session.load(FiscalYearPeriod.class, pk);

   System.out.println(fiscalYearPeriod.getPeriodSts());

   session.getTransaction().commit();
  }catch(Exception e) {
   e.printStackTrace();
   session.getTransaction().rollback();
  }finally {
   HibernateUtils.closeSession(session);
  }
}