Spring之ORM模块

n672 7年前

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>