我将如何从DAO中的ServletContext获取SessionFactory [英] How would I obtain SessionFactory from the ServletContext in the DAO

问题描述

我已经创建了这样的DAO：这是基于： Hibernate：CRUD通用DAO

  public class Dao {
 SessionFactory sessionFactory; 
 //初始化会话工厂
 public用户保存（User o）{
 return（User）sessionFactory.getCurrentSession（）。save（o）; 
} 
 
 public用户获得（Long id）{
 return（User）sessionFactory.getCurrentSession（）。get（User.class，id）; 
} 
 
 public void saveOrUpdate（User o）{
 sessionFactory.getCurrentSession（）。saveOrUpdate（o）; 
 
 $ / code> 

现在，这很好，如果我的sessionFactory在DAO或者其他类。但我的问题是从servletContextListener调用SessionFactory：这是我在监听器中的代码：



  public void contextInitialized（ServletContextEvent event）{ 
 StandardServiceRegistry registry = new StandardServiceRegistryBuilder（）。configure（）。build（）; 
 try {
 sessionFactory = new MetadataSources（registry）.buildMetadata（）。buildSessionFactory（）; 
 event.getServletContext（）。setAttribute（factory，sessionFactory）; 
} catch（Exception e）{
 e.printStackTrace（）; 
 StandardServiceRegistryBuilder.destroy（registry）; 
 
 
 
 
 $ b 
在这种情况下，我如何从DAO调用SessionFactory除了实际包装一个servletRequest到DAO中吗？
解决方案
 强烈阻止存储Hibernate  SessionFactory 转换为Servlet的 ServletContext 。另外，让你的DAO使用你的Hibernate  Session 来代替。
 
 
 
解决你的Hibernate  SessionFactory 实例化一次，我创建了一个单例类来管理它： 
 
 
  / ** 
 * 
 * / 
包za.co.sindi.persistence.util; 
 
 import java.util.logging.Level; 
 import java.util.logging.Logger; 
 
 import org.hibernate.HibernateException; 
 import org.hibernate.Interceptor; 
 import org.hibernate.Session; 
 import org.hibernate.SessionFactory; 
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 
导入org.hibernate.cfg.Configuration; 
 import org.hibernate.service.ServiceRegistry; 
 
 / ** 
 *这是一个严格使用Hibernate 4.x库的Hibernate实用程序类。 
 * 
 * @author Buhake Sindi 
 * @since 26 November 2012 
 * 
 * / 
 public final class HibernateUtils {
 
 private static final Logger logger = Logger.getLogger（HibernateUtils.class.getName（））; 
 private static配置配置; 
 private static SessionFactory sessionFactory; 
 private static ServiceRegistry serviceRegistry; 
 private static final ThreadLocal< Session> sessionThread = new ThreadLocal< Session>（）; 
 private static final ThreadLocal< Interceptor> interceptorThread = new ThreadLocal< Interceptor>（）; 
 
 static {
 try {
 configuration = new Configuration（）; 
 serviceRegistry = new StandardServiceRegistryBuilder（）。build（）; 
 sessionFactory = configuration.configure（）。buildSessionFactory（serviceRegistry）; 
} catch（HibernateException e）{
 logger.log（Level.SEVERE，Error intializing SessionFactory。，e.getLocalizedMessage（））; 
抛出新的ExceptionInInitializerError（e）; 
 
 
 $ b $ ** 
私有构造函数
 * / 
 private HibernateUtils（）{} 
 
 / ** 
 * @return sessionFactory 
 * / 
 public static SessionFactory getSessionFactory（）{
 return sessionFactory; 
} 
 
 / ** 
 *检索线程本地的当前会话。 
 * 
 *返回当前线程的Hibernate {@link Session}。 
 *当Hibernate打开一个新会话时出现问题时，引发HibernateException。 
 * / 
 public static Session getSession（）{
 Session session = sessionThread.get（）; 
 if（session == null）{
 Interceptor interceptor = getInterceptor（）; 
 if（interceptor！= null）{
 session = getSessionFactory（）。withOptions（）。interceptor（interceptor）.openSession（）; 
} else {
 session = getSessionFactory（）。openSession（）; 
} 
 
 if（session！= null）{
 sessionThread.set（session）; 
} 
} 
 
返回会话; 
 
 $ b $ ** 
 *关闭Hibernate Session（从< code> getSession（）< / code>会话创建
 * / 
 public static void closeSession（）{
 Session session = sessionThread.get（）; 
 sessionThread.set（null）; 
 if（session！= null&&&session; isOpen（））{
 session.close（）; 
} 
} 
 
 / ** 
 *注册一个Hibernate {@link拦截器}。 
 * @param interceptor 
 * / 
 public static void registerInterceptor（Interceptor interceptor）{
 interceptorThread.set（interceptor）; 
} 
 
 / ** 
 *获取注册的Hibernate拦截器。
 * @return 
 * / 
 public static Interceptor getInterceptor（）{
 return interceptorThread.get（）; 
 
 
 
 
 
 
 
在我的DAO中，我只是将会话检索为 HibernateUtils.getSession（）; 。 
这样，我的MVC应用程序就没有提及我特定的DAO实现。
 
 
 
我希望这有助于。
 
I have created a DAO like this: This is based from: Hibernate: CRUD Generic DAO
public class Dao{
    SessionFactory sessionFactory;
    // initialise session factory
    public User save(User o){
        return (User) sessionFactory.getCurrentSession().save(o);
    }

    public User get(Long id){
        return (User) sessionFactory.getCurrentSession().get(User.class, id);
    }

    public User void saveOrUpdate(User o){
                    sessionFactory.getCurrentSession().saveOrUpdate(o);
    }
Now, this is all fine, if my sessionFactory is in the DAO or in other classes. But my problem is calling SessionFactory from the servletContextListener: Here is my code in the listener:
public void contextInitialized(ServletContextEvent event)  {
    StandardServiceRegistry registry = new StandardServiceRegistryBuilder().configure().build();
    try {
        sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();
        event.getServletContext().setAttribute("factory", sessionFactory);
    } catch(Exception e) {
        e.printStackTrace();
        StandardServiceRegistryBuilder.destroy( registry );
    }
}
How would I call SessionFactory from the DAO in this case aside from actually wrapping a servletRequest inside the DAO?
解决方案
I strongly discourage storing Hibernate SessionFactory into Servlet's ServletContext. Also, have your DAO use your Hibernate Session instead.

To tackle your issue of having your Hibernate SessionFactory instantiated once, I created a singleton class to manage this:
/**
 * 
 */
package za.co.sindi.persistence.util;

import java.util.logging.Level;
import java.util.logging.Logger;

import org.hibernate.HibernateException;
import org.hibernate.Interceptor;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

/**
 * This is a Hibernate utility class that strictly uses the Hibernate 4.x library.
 * 
 * @author Buhake Sindi
 * @since 26 November 2012
 *
 */
public final class HibernateUtils {

    private static final Logger logger = Logger.getLogger(HibernateUtils.class.getName());
    private static Configuration configuration;
    private static SessionFactory sessionFactory;
    private static ServiceRegistry serviceRegistry;
    private static final ThreadLocal<Session> sessionThread = new ThreadLocal<Session>();
    private static final ThreadLocal<Interceptor> interceptorThread = new ThreadLocal<Interceptor>();

    static {
        try {
            configuration = new Configuration();
            serviceRegistry = new StandardServiceRegistryBuilder().build();
            sessionFactory = configuration.configure().buildSessionFactory(serviceRegistry);
        } catch (HibernateException e) {
            logger.log(Level.SEVERE, "Error intializing SessionFactory.", e.getLocalizedMessage());
            throw new ExceptionInInitializerError(e);
        }
    }

    /**
     * Private constructor
     */
    private HibernateUtils() {}

    /**
     * @return the sessionFactory
     */
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    /**
     * Retrieves the current session local to the thread.
     * 
     * @return Hibernate {@link Session} for current thread.
     * @throws HibernateException when Hibernate has a problem opening a new session.
     */
    public static Session getSession() {
        Session session = sessionThread.get();
        if (session == null) {
            Interceptor interceptor = getInterceptor();
            if (interceptor != null) {
                session = getSessionFactory().withOptions().interceptor(interceptor).openSession();
            } else {
                session = getSessionFactory().openSession();
            }

            if (session != null) {
                sessionThread.set(session);
            }
        }

        return session;
    }

    /**
     * Closes the Hibernate Session (created from the <code>getSession()</code> session.
     */
    public static void closeSession() {
        Session session = sessionThread.get();
        sessionThread.set(null);
        if (session != null && session.isOpen()) {
            session.close();
        }
    }

    /**
     * Registers a Hibernate {@link Interceptor}.
     * @param interceptor
     */
    public static void registerInterceptor(Interceptor interceptor) {
        interceptorThread.set(interceptor);
    }

    /**
     * Get the registered Hibernate Interceptor.
     * @return
     */
    public static Interceptor getInterceptor() {
        return interceptorThread.get();
    }
}
And in my DAO, I just retrieve the session as HibernateUtils.getSession();.
That way, my MVC application has no reference to my specific DAO implementation.

I hope this helps.

                        
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