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>