Hibernate复合主键

当一个表里有多个字段组成的复合主键时,hibernate怎么处理的呢?

复合主键映射

通常将复合主键相关属性，单独抽取出来，建立一个独立的类
  * 必须实现序列化接口
  * 必须实现equals和hashcode方法
  
  采用<composite-id>标签进行映射，其它属性采用<property>正常映射

 

如下:

配置如下:

<?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" column="fiscal_year"/>
			<key-property name="fiscalPeriod" column="fiscal_period"/>
		</composite-id>
		<property name="beginDate" column="begin_date"/>
		<property name="endDate" column="end_date"/>
		<property name="periodSts" column="period_sts"/>
	</class>
</hibernate-mapping>	

 

POJO如下:

我们把复合主键的两个字段抽取出来放在一个POJO中.并将它作为另一POJO的组件.

package com.bjsxt.hibernate;

import java.util.Date;

public class FiscalYearPeriod {
	
	private FiscalYearPeriodPK fiscalYearPeriodPK;
	
	private Date beginDate;
	
	private Date endDate;
	
	private String periodSts;

	public Date getBeginDate() {
		return beginDate;
	}

	public void setBeginDate(Date beginDate) {
		this.beginDate = beginDate;
	}

	public Date getEndDate() {
		return endDate;
	}

	public void setEndDate(Date endDate) {
		this.endDate = endDate;
	}

	public String getPeriodSts() {
		return periodSts;
	}

	public void setPeriodSts(String periodSts) {
		this.periodSts = periodSts;
	}

	public FiscalYearPeriodPK getFiscalYearPeriodPK() {
		return fiscalYearPeriodPK;
	}

	public void setFiscalYearPeriodPK(FiscalYearPeriodPK fiscalYearPeriodPK) {
		this.fiscalYearPeriodPK = fiscalYearPeriodPK;
	}
}

 

package com.bjsxt.hibernate;

import java.io.Serializable;

public class FiscalYearPeriodPK implements Serializable {

	private int fiscalYear;
	
	private int fiscalPeriod;

	public int getFiscalPeriod() {
		return fiscalPeriod;
	}

	public void setFiscalPeriod(int fiscalPeriod) {
		this.fiscalPeriod = fiscalPeriod;
	}

	public int getFiscalYear() {
		return fiscalYear;
	}

	public void setFiscalYear(int fiscalYear) {
		this.fiscalYear = fiscalYear;
	}

	@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;
	}
	
	
}

 

 

注意实现equals和hscode方法,并且实现Serializable接口.

这样会在数据库里面生成表:t_fiscal_year_period,它有两个字段fiscalYear,fiscalPeriod作为主键

表结构如下:

mysql> desc t_fiscal_year_period;
+---------------+--------------+------+-----+---------+-------+
| Field         | Type         | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+-------+
| fiscal_year   | int(11)      | NO   | PRI |         |       |
| fiscal_period | int(11)      | NO   | PRI |         |       |
| begin_date    | datetime     | YES  |     | NULL    |       |
| end_date      | datetime     | YES  |     | NULL    |       |
| period_sts    | varchar(255) | YES  |     | NULL    |       |
+---------------+--------------+------+-----+---------+-------+
5 rows in set (0.05 sec)

 

 

测试类:

package com.bjsxt.hibernate;

import java.util.Date;

import org.hibernate.Session;

import junit.framework.TestCase;

public class FiscalYearPeriodTest extends TestCase {
	
	public void testSave() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			//复合主键
			FiscalYearPeriodPK fiscalYearPeriodPK = new FiscalYearPeriodPK();
			fiscalYearPeriodPK.setFiscalYear(2007);
			fiscalYearPeriodPK.setFiscalPeriod(8);
			
			FiscalYearPeriod fiscalYearPeriod = new FiscalYearPeriod();
			
			//和主键建立关联
			fiscalYearPeriod.setFiscalYearPeriodPK(fiscalYearPeriodPK);
			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();
			//复合主键
			FiscalYearPeriodPK fiscalYearPeriodPK = new FiscalYearPeriodPK();
			fiscalYearPeriodPK.setFiscalYear(2007);
			fiscalYearPeriodPK.setFiscalPeriod(8);
			FiscalYearPeriod fiscalYearPeriod = (FiscalYearPeriod)session.load(FiscalYearPeriod.class, fiscalYearPeriodPK);
			System.out.println("beginDate=" + fiscalYearPeriod.getBeginDate());
			System.out.println("endDate=" + fiscalYearPeriod.getEndDate());
			System.out.println("periodSts=" + fiscalYearPeriod.getPeriodSts());
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}

}