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>