Spring之ORM模块代码详解

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--> 
          <propkeypropkey="*">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>

总结

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Spring之ORM模块代码详解

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