Hibernate 关联关系解除

　　Hibernate对于持久化实体间的关联关系解除，有两种实现方式，一种是将关联关系实体中彻底删除，而另一种则是将关联关系的外键值设为空，即NULL。两种方式在配置文件中的体现为为cascade设置不同的值。

　　一。Husband

package com.dream.model.join;import java.util.Set;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:46 PM*/
public class Husband {private Integer id;private String name;private Set<Wife> wifes;public Husband(String name) {this.name = name;}public Husband() {}public Husband(String name, Set<Wife> wifes) {this.name = name;this.wifes = wifes;}public Set<Wife> getWifes() {return wifes;}public Integer getId() {return id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

<?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"><hibernate-mapping default-access="field"><class name="com.dream.model.join.Husband" table="husband" dynamic-insert="true" dynamic-update="true"><id name="id" column="id" type="java.lang.Integer"><generator class="native"/></id><property name="name" column="name" type="java.lang.String"/><set name="wifes" table="wife" cascade="all-delete-orphan"><key column="husbandid"/><one-to-many class="com.dream.model.join.Wife"/></set></class></hibernate-mapping>

　　二。Wife

package com.dream.model.join;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:47 PM*/
public class Wife {private Integer id;private String name;private Husband husband;public Wife(String name) {this.name = name;}public Wife() {}public Wife(String name, Husband husband) {this.name = name;this.husband = husband;}public String getName() {return name;}public Husband getHusband() {return husband;}
}

<?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"><hibernate-mapping default-access="field"><class name="com.dream.model.join.Wife" table="wife" dynamic-insert="true" dynamic-update="true"><id name="id" column="id" type="java.lang.Integer"><generator class="native"/></id><property name="name" column="name" type="java.lang.String"/><many-to-one name="husband" class="com.dream.model.join.Husband" column="husbandid"/></class></hibernate-mapping>

　　三。CoupleDao

package com.dream.dao.standard;import com.dream.model.join.Husband;
import com.dream.model.join.Wife;import java.util.Set;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:51 PM*/
public interface CoupleDao {Husband findHusbandById(Integer id);void saveOrUpdateHusband(Husband husband);void deleteHusband(Husband husband);
}

package com.dream.dao;import com.dream.dao.standard.CoupleDao;
import com.dream.model.join.Husband;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;import java.util.List;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:52 PM*/
public class CoupleDaoImpl extends HibernateDaoSupport implements CoupleDao {public Husband findHusbandById(Integer id) {List<Husband> husbands = getHibernateTemplate().find("from Husband husband where husband.id=?", id);if (husbands.isEmpty()) {return null;}return husbands.get(0);}public void saveOrUpdateHusband(Husband husband) {getHibernateTemplate().saveOrUpdate(husband);}public void deleteHusband(Husband husband) {getHibernateTemplate().delete(husband);}
}

　　四。CoupleService

package com.dream.service.standard;import com.dream.model.join.Husband;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:53 PM*/
public interface CoupleService {Husband loadHusbandById(Integer id);void saveOrUpdateHusband(Husband husband);void deleteHusbandById(Integer id);
}

package com.dream.service;import com.dream.dao.standard.CoupleDao;
import com.dream.exception.DataNotExistException;
import com.dream.model.join.Husband;
import com.dream.service.standard.CoupleService;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 5:53 PM*/
public class CoupleServiceImpl implements CoupleService {private CoupleDao coupleDao;public Husband loadHusbandById(Integer id) {Husband husband = coupleDao.findHusbandById(id);if (husband == null) {throw new DataNotExistException();}return husband;}public void saveOrUpdateHusband(Husband husband) {coupleDao.saveOrUpdateHusband(husband);}public void deleteHusbandById(Integer id) {Husband husband = coupleDao.findHusbandById(id);coupleDao.deleteHusband(husband);}public void setCoupleDao(CoupleDao coupleDao) {this.coupleDao = coupleDao;}
}

package com.dream.exception;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 6:01 PM*/
public class DataNotExistException extends RuntimeException {public DataNotExistException() {super("The data you find does not exist in the database.");}
}

　　五。testDatasource

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:aop="http://www.springframework.org/schema/aop"xmlns:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"default-autowire="byName"><context:property-placeholder location="classpath:testDB.properties"/><bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"destroy-method="close"><property name="driverClassName" value="${db.driver}"/><property name="url" value="${db.url}"/><property name="username" value="${db.username}"/><property name="password" value="${db.password}"/></bean><bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"><property name="dataSource" ref="dataSource"/><property name="mappingLocations"><list><value>/hibernate_mappings/Husband.hbm.xml</value><value>/hibernate_mappings/Wife.hbm.xml</value></list></property><property name="hibernateProperties"><props><prop key="hibernate.dialect">${hibernate.dialect}</prop><prop key="hibernate.show_sql">${hibernate.show_sql}</prop><prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop><prop key="hibernate.jdbc.batch_size">${hibernate.jdbc.batch_size}</prop></props></property></bean><bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate"><property name="sessionFactory" ref="sessionFactory"/></bean><bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"><property name="sessionFactory" ref="sessionFactory"/></bean><tx:advice id="txAdvice" transaction-manager="transactionManager"><tx:attributes><tx:method name="*" propagation="REQUIRED"/></tx:attributes></tx:advice><aop:config><aop:pointcut id="service" expression="execution(* com.dream.service..*.*(..))"/><aop:advisor advice-ref="txAdvice" pointcut-ref="service"/></aop:config><bean id="coupleDao" class="com.dream.dao.CoupleDaoImpl"><property name="sessionFactory" ref="sessionFactory"/></bean><bean id="coupleService" class="com.dream.service.CoupleServiceImpl"><property name="coupleDao" ref="coupleDao"/></bean>
</beans>

　　六。testDB

db.url=jdbc:mysql://localhost:3306/test_fetchdb.driver=com.mysql.jdbc.Driverdb.username=rootdb.password=roothibernate.dialect=org.hibernate.dialect.MySQL5Dialecthibernate.show_sql=truehibernate.hbm2ddl.auto=updatehibernate.jdbc.batch_size=100

　　七。TestCase

package com.fetch;import com.dream.model.join.Husband;
import com.dream.model.join.Wife;
import com.dream.service.standard.CoupleService;
import junit.framework.TestCase;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;import java.util.HashSet;
import java.util.Set;/*** Created by IntelliJ IDEA.* User: Zhong Gang* Date: 9/26/11* Time: 6:05 PM*/
public class HibernateCascadeTest extends TestCase {private CoupleService coupleService;@Overridepublic void setUp() throws Exception {ApplicationContext context = new ClassPathXmlApplicationContext("classpath:testDatasource.xml");coupleService = (CoupleService) context.getBean("coupleService");}public void testCascadeAllDelete() throws Exception {Wife wife1 = new Wife("Wife1");Wife wife2 = new Wife("Wife2");Set<Wife> wifes = new HashSet<Wife>();wifes.add(wife1);wifes.add(wife2);Husband husband = new Husband("Husband1", wifes);coupleService.saveOrUpdateHusband(husband);coupleService.deleteHusbandById(husband.getId());}
}

　　Scenario 1：cascade="all-delete-orphan"　in Husband.hbm.xml

Hibernate: insert into husband (name) values (?)
Hibernate: insert into wife (name) values (?)
Hibernate: insert into wife (name) values (?)
Hibernate: update wife set husbandid=? where id=?
Hibernate: update wife set husbandid=? where id=?
Hibernate: select husband0_.id as id0_, husband0_.name as name0_ from husband husband0_ where husband0_.id=?
Hibernate: select wifes0_.husbandid as husbandid0_1_, wifes0_.id as id1_, wifes0_.id as id1_0_, wifes0_.name as name1_0_, wifes0_.husbandid as husbandid1_0_ from wife wifes0_ where wifes0_.husbandid=?
Hibernate: update wife set husbandid=null where husbandid=?
Hibernate: delete from wife where id=?
Hibernate: delete from wife where id=?
Hibernate: delete from husband where id=?

　　Scenario 2：cascade="all"　in Husband.hbm.xml

　　结论同上

　　Scenario 3：cascade="delete"　in Husband.hbm.xml

　　结论同上

　　Scenario 4：cascade="delete-orphan"　in Husband.hbm.xml

　　结论同上

　　Scenario 5：cascade="save-update"　in Husband.hbm.xml

Hibernate: insert into husband (name) values (?)
Hibernate: insert into wife (name) values (?)
Hibernate: insert into wife (name) values (?)
Hibernate: update wife set husbandid=? where id=?
Hibernate: update wife set husbandid=? where id=?
Hibernate: select husband0_.id as id0_, husband0_.name as name0_ from husband husband0_ where husband0_.id=?
Hibernate: update wife set husbandid=null where husbandid=?
Hibernate: delete from husband where id=?

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