Spring之ORM模块

ORM模块对Hibernate、JDO、TopLinkiBatis等ORM框架提供支持

ORM模块依赖于dom4j.jar、antlr.jar等包

在Spring里，Hibernate的资源要交给Spring管理，Hibernate以及其SessionFactory等知识Spring一个特殊的Bean，有Spring负责实例化与销毁。因此DAO层只需要继承HibernateDaoSupport，而不需要与Hibernate的API打交道，不需要开启、关闭Hibernate的Session、Transaction，Spring会自动维护这些对象

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" />
<!--  该Package下的所有类都会被当做实体类加载-->
<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配置的实体类，则改为

<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默认在DAO层添加事务，DAO层的每个方法为一个事务。Spring+Hibernate编程中，习惯的做法实在DAO层上再添加一个Service层，然后把事务配置在Service层

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

分层的做法是，程序调用Service层，Service层调用DAO层，DAO层调用Hibernate实现数据访问，原则上不允许跨曾访问。分层使业务层次更加清晰

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层配置事务管理

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

<!--  事务管理规则-->
<bean id="hibernateTransactionAttributeSource" class=" org.springframework.transaction.interceptor.NameMatchTransactionAttributeSource">
      <property name="properties">
             <props><!--  为所有方法加上事务-->
                    <propkey="*">PROPGATION_REQUIRED</prop>
      </property>
</bean>

<!--  事务工厂代理类，将Service实现类、事务管理器、事务管理规则组装在一起-->
<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>