Spring之ORM模塊

ORM模塊對Hibernate、JDO、TopLinkiBatis等ORM框架提供支持

ORM模塊依賴于dom4j.jar、antlr.jar等包

在Spring里，Hibernate的資源要交給Spring管理，Hibernate以及其SessionFactory等知識Spring一個特殊的Bean，有Spring負責實例化與銷毀。因此DAO層只需要繼承HibernateDaoSupport，而不需要與Hibernate的API打交道，不需要開啟、關閉Hibernate的Session、Transaction，Spring會自動維護這些對象

public interface ICatDao{
      public void createCat(Cat cat);
      public List<Cat> listCats();
      public int getCatsCount();
      public Cat findCatByName(String name);
}

import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
public class CatDaoImpl extends HibernateDaoSupportimplements ICatDao{
      public void createCat(Cat cat){
             this.getHibernateTemplate().persist(cat);
      }
      public List<Cat> listCats(){
             return this. getHibernateTemplate().find(＂select cfrom Cat c＂);
      }
      public int getCatsCount(){
             Number n = (Number)this.getSession(true).createQuery(＂selectcount(c) from Cat c＂).uniqueResult();
             return n.intValue();
      }
      public Cat findCatByName(String name){
             List<Cat> catList =this.getHibernateTemplate().find(＂select c from Cat where c.name = ?＂,name);
             if(catList.size()>0)
                    return catList.get(0);
             return null;
      }

}

<bean id=＂sessionFactory＂ class=＂org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean＂destroy-method=＂destroy＂>
<property name=＂dataSource＂ ref=＂dataSource＂ />
<!--  該Package下的所有類都會被當做實體類加載-->
<property name=＂annotatedPackages＂ value=＂classpath:/com/clf/orm＂ />
<property name=＂anotatedClasses＂>
      <list>
             <value>com.clf.spring.orm.Cat</value>
             <value>com.clf.spring.orm.Dog</value>
      </list>
<property name=＂hibernateProperties＂>
      <props>
             <prop key=＂hiberante.dialect＂>org.hibernate.dialect.MySQLDialect</prop>
             <prop key=＂hibernate.show_sql＂>true</prop>
             <prop key=＂ hibernate.format_sql＂>true</prop>
             <prop key=＂ hibernate.hbm2ddl.auto＂>create</prop>
      </props>
</property>

<bean id=＂catDao＂ class=＂com.clf.spring.orm.CatDaoImpl＂>
      <property name=＂sessionFactory＂ ref=＂ sessionFactory＂/>
</bean>

如果使用XML配置的實體類，則改為

<bean id=＂sessionFactory＂ class=＂org.springframework.orm.hibernate3.LocalSessionFactoryBean＂destroy-method=＂destroy＂>
<property name=＂mappingResources＂>
      <list>
             <value>classpath:/com/clf/orm/Cat.hbm.xml</value>
      </list>
</property>
……
</bean>

Spring默認在DAO層添加事務，DAO層的每個方法為一個事務。Spring+Hibernate編程中，習慣的做法實在DAO層上再添加一個Service層，然后把事務配置在Service層

public interface ICatService{
      public void createCat(Cat cat);
      public List<Cat> listCats();
      public int getCatsCount();
}

分層的做法是，程序調用Service層，Service層調用DAO層，DAO層調用Hibernate實現數據訪問，原則上不允許跨曾訪問。分層使業務層次更加清晰

public class CatServiceImpl implements ICatService{
      private IDao catDao;
      public IDao getCatDao(){
             return catDao;
      }

      public void setCatDao(IDao dao){
             this.catDao = dao;
      }

      public void createCat(Cat cat){
             catDao.createCat(cat);
      }
      public List<Cat> listCats(){
             return catDao.listCats();
      }
      public int getCatsCount(){
             return catDao.getCatsCount();
      }

}

然后再Service層配置事務管理

<!--  事務管理器-->
<bean id=＂hibernateTransactionManager＂ class=＂ org.springframework.orm.hibernate3.HibernateTransactionManager
＂>
      <property name=＂sessionFactory＂ ref=＂sessionFactory＂/>
</bean>

<!--  事務管理規則-->
<bean id=＂hibernateTransactionAttributeSource＂ class=＂ org.springframework.transaction.interceptor.NameMatchTransactionAttributeSource＂>
      <property name=＂properties＂>
             <props><!--  為所有方法加上事務-->
                    <propkey=＂*＂>PROPGATION_REQUIRED</prop>
      </property>
</bean>

<!--  事務工廠代理類，將Service實現類、事務管理器、事務管理規則組裝在一起-->
<bean id=＂catService＂ class=＂org.springframework.transaction.interceptor.TransactionProxyFactoryBean＂>
      <property name=＂transactionManager＂ ref=＂ hibernateTransactionManager＂>
      <property name=＂target＂>
             <bean class=＂com.clf.spring.orm.CatServiceImpl＂ >
                    <property name=＂catDao＂ ref=＂catDao＂/>
             </bean>
      </property>
      <property name=＂transactionAttributeSource＂ ref=＂ hibernateTransactionAttributeSource＂ />
</bean>