Spring之ORM模块代码详解

spring框架七大模块简单介绍

spring中mvc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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