7.7--SSH学习之Hibernate Session

本文主要是介绍7.7--SSH学习之Hibernate Session，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

the first picture:

the second picture:

首先来两张图

第一张图：大概意思是one.jsp把数据提交到servlet，（这里已开启一个新的事务，也是一个新的session），然后调用servive层，再调用dao层，最后在数据库查询数据，然后把数据返回到dao层，service层，servlet，最后在two.jsp中显示查询结果。在servlet向two.jsp提交查询结果之前，先解析jsp，然后提交事务，这时session也就关闭了。
总结：一次请求开启一个新的session

第二张图：jsp页面向servlet,service,dao层提交请求，要先经过过滤器，最后到数据库；返回数据也是一样，最后也要经过过滤器才能在jsp页面中显示查询结果

举个例子：

HibernateUtil .java

public class HibernateUtil {private static final SessionFactory sessionFactory = buildSessionFactory();private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();private static SessionFactory buildSessionFactory() {try {// Create the SessionFactory from hibernate.cfg.xmlConfiguration cfg = new  Configuration().configure();SessionFactory sf= cfg.buildSessionFactory(new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build());return sf;}catch (Throwable ex) {// Make sure you log the exception, as it might be swallowedSystem.err.println("Initial SessionFactory creation failed." + ex);throw new ExceptionInInitializerError(ex);}}public static SessionFactory getSessionFactory() {return sessionFactory;}public static Session getSession(){Session session = threadLocal.get();if(session == null || !session.isOpen()){   //判断session是否为空，或者没打开session = getSessionFactory().getCurrentSession();threadLocal.set(session);}return session;}}

GenericDaoImpl .java//相当于baseDaoImpl,接口的父类

public class GenericDaoImpl implements GenericDao {private Class genericEntity;public Class getGenericEntity() {return genericEntity;}public void setGenericEntity(Class genericEntity) {this.genericEntity = genericEntity;}@Overridepublic void addEntity(Object obj) {// TODO Auto-generated method stubtry{Session session = HibernateUtil.getSession();//session.beginTransaction();session.save(obj);//session.getTransaction().commit();}catch(Exception e){e.printStackTrace();}}@Overridepublic void deleteEntity(Object obj) {// TODO Auto-generated method stubtry{Session session = HibernateUtil.getSession();//session.beginTransaction();session.delete(obj);//session.getTransaction().commit();}catch(Exception e){e.printStackTrace();}}@Overridepublic void updateEntity(Object obj) {// TODO Auto-generated method stubtry{Session session = HibernateUtil.getSession();//session.beginTransaction();session.update(obj);//session.getTransaction().commit();}catch(Exception e){e.printStackTrace();}}@Overridepublic Object findById(Serializable entityId) {// TODO Auto-generated method stubObject obj = null;try{Session session = HibernateUtil.getSession();//session.beginTransaction();obj = session.load(genericEntity, entityId);//session.getTransaction().commit();}catch(Exception e){e.printStackTrace();}return obj;}@Overridepublic List findAll() {// TODO Auto-generated method stubList list = new ArrayList();try{Session session = HibernateUtil.getSession();//session.beginTransaction();list = session.createQuery("from "+genericEntity.getName()).list();//session.getTransaction().commit();}catch(Exception e){e.printStackTrace();}return list;}}

过滤器OpenSessionInViewFilter .java

public class OpenSessionInViewFilter implements Filter {@Overridepublic void destroy() {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {System.out.println("客户端请求服务器执行代码");Session session = HibernateUtil.getSession();session.beginTransaction();chain.doFilter(request,response);System.out.println("服务器响应客户器执行代码");session.getTransaction().commit();}@Overridepublic void init(FilterConfig arg0) throws ServletException {}}