Question

调用PageFacade的正确方法是什么，或PageFacade如何修改，以便调用PageJpaController.create()？我不太确定如何将通用AbstractFacade类用于此目的。虽然我知道以下类是相关的，但我并不完全确定如何组织和调用方法。

数据库操作位于library：

AggregatorJpaLibrary/src/net/bounceme/dur/selenium/jpa/
├── AbstractFacade.java
├── exceptions
│   ├── IllegalOrphanException.java
│   └── NonexistentEntityException.java
├── Feed.java
├── FeedJpaController.java
├── LinkFacade.java
├── Link.java
├── LinkJpaController.java
├── PageFacade.java
├── Page.java
└── PageJpaController.java

client迭代数据库中的网址：

package net.bounceme.dur.aggregator.client;

import java.util.Date;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.logging.Logger;
import net.bounceme.dur.selenium.jpa.Link;
import net.bounceme.dur.selenium.jpa.LinkFacade;
import net.bounceme.dur.selenium.jpa.Page;
import net.bounceme.dur.selenium.jpa.PageFacade;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class SeleniumWebPageIterator {

    private final static Logger log = Logger.getLogger(SeleniumWebPageIterator.class.getName());
    private final PageFacade pageFacade = new PageFacade();
    private final LinkFacade linkFacade = new LinkFacade();

    public SeleniumWebPageIterator() {
    }

    public void processLinks() {
        List<Link> links = linkFacade.findAll();
        for (Link l : links) {
            processLink(l);
        }
    }

    private void processLink(Link l) {
        log.fine(l.toString());
        WebDriver driver = new FirefoxDriver();
        driver.get(l.getLink());
        driver.manage().timeouts().implicitlyWait(9, TimeUnit.SECONDS);
        String s = driver.getPageSource();
        createPage(l, s);
        driver.close();
    }

    private void createPage(Link l, String s) {
        Page p = new Page();
        p.setCreated(new Date());
        p.setLinkId(l.getId());
        p.setPage(s);
        pageFacade.create(p);
    }
}

数据库中有链接（URL＆＃39; s），Selenium访问了网页。但是，页面的源HTML不会保留。

PageFacade很简单：

package net.bounceme.dur.selenium.jpa;

import java.util.logging.Logger;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class PageFacade extends AbstractFacade {

    private final static Logger log = Logger.getLogger(PageFacade.class.getName());
    private final EntityManagerFactory emf = Persistence.createEntityManagerFactory("SeleniumIteratorPU");
//    @PersistenceContext(unitName = "SeleniumReaderPU")

    public PageFacade() {
        super(Page.class);
    }

    @Override
    protected EntityManager getEntityManager() {
        return emf.createEntityManager();
    }
}

并扩展，当然，AbstractFacade：

package net.bounceme.dur.selenium.jpa;

import java.util.List;
import java.util.logging.Logger;
import javax.persistence.EntityManager;

public abstract class AbstractFacade<T> {

    private final static Logger log = Logger.getLogger(AbstractFacade.class.getName());
    private Class<T> entityClass;

    public AbstractFacade(Class<T> entityClass) {
        this.entityClass = entityClass;
    }

    protected abstract EntityManager getEntityManager();

    //how to invoke the JpaController create method?
    public void create(T entity) {
        getEntityManager().persist(entity);
        log.info("..persisted!");
    }

    public void edit(T entity) {
        getEntityManager().merge(entity);
    }

    public void remove(T entity) {
        getEntityManager().remove(getEntityManager().merge(entity));
    }

    public T find(Object id) {
        return getEntityManager().find(entityClass, id);
    }

    public List<T> findAll() {
        javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
        cq.select(cq.from(entityClass));
        return getEntityManager().createQuery(cq).getResultList();
    }

    public List<T> findRange(int[] range) {
        javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
        cq.select(cq.from(entityClass));
        javax.persistence.Query q = getEntityManager().createQuery(cq);
        q.setMaxResults(range[1] - range[0] + 1);
        q.setFirstResult(range[0]);
        return q.getResultList();
    }

    public int count() {
        javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
        javax.persistence.criteria.Root<T> rt = cq.from(entityClass);
        cq.select(getEntityManager().getCriteriaBuilder().count(rt));
        javax.persistence.Query q = getEntityManager().createQuery(cq);
        return ((Long) q.getSingleResult()).intValue();
    }

}

使用或应该使用PageJpaController实际持久保存到数据库：

package net.bounceme.dur.selenium.jpa;

import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Query;
import javax.persistence.EntityNotFoundException;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import net.bounceme.dur.selenium.jpa.exceptions.NonexistentEntityException;

public class PageJpaController implements Serializable {

    public PageJpaController(EntityManagerFactory emf) {
        this.emf = emf;
    }
    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

    public void create(Page page) {
        EntityManager em = null;
        try {
            em = getEntityManager();
            em.getTransaction().begin();
            em.persist(page);
            em.getTransaction().commit();
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void edit(Page page) throws NonexistentEntityException, Exception {
        EntityManager em = null;
        try {
            em = getEntityManager();
            em.getTransaction().begin();
            page = em.merge(page);
            em.getTransaction().commit();
        } catch (Exception ex) {
            String msg = ex.getLocalizedMessage();
            if (msg == null || msg.length() == 0) {
                Integer id = page.getId();
                if (findPage(id) == null) {
                    throw new NonexistentEntityException("The page with id " + id + " no longer exists.");
                }
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void destroy(Integer id) throws NonexistentEntityException {
        EntityManager em = null;
        try {
            em = getEntityManager();
            em.getTransaction().begin();
            Page page;
            try {
                page = em.getReference(Page.class, id);
                page.getId();
            } catch (EntityNotFoundException enfe) {
                throw new NonexistentEntityException("The page with id " + id + " no longer exists.", enfe);
            }
            em.remove(page);
            em.getTransaction().commit();
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public List<Page> findPageEntities() {
        return findPageEntities(true, -1, -1);
    }

    public List<Page> findPageEntities(int maxResults, int firstResult) {
        return findPageEntities(false, maxResults, firstResult);
    }

    private List<Page> findPageEntities(boolean all, int maxResults, int firstResult) {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            cq.select(cq.from(Page.class));
            Query q = em.createQuery(cq);
            if (!all) {
                q.setMaxResults(maxResults);
                q.setFirstResult(firstResult);
            }
            return q.getResultList();
        } finally {
            em.close();
        }
    }

    public Page findPage(Integer id) {
        EntityManager em = getEntityManager();
        try {
            return em.find(Page.class, id);
        } finally {
            em.close();
        }
    }

    public int getPageCount() {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            Root<Page> rt = cq.from(Page.class);
            cq.select(em.getCriteriaBuilder().count(rt));
            Query q = em.createQuery(cq);
            return ((Long) q.getSingleResult()).intValue();
        } finally {
            em.close();
        }
    }

}

如何确保实际使用PageJpaController？

Answer 1

从提供的设计看来，AbstractFacade的子类，PageFacade默认将使用EntityManager的原始jpa持久性方法。要调用jpa控制器实现，可以覆盖AbstractFacade的方法。

例如，

....
public class PageFacade extends AbstractFacade<Page> {

private final static Logger log = Logger.getLogger(PageFacade.class.getName());
private final EntityManagerFactory emf = Persistence.createEntityManagerFactory("SeleniumIteratorPU");
private PageJpaController controller;

public PageFacade() {
    super(Page.class);
    controller = new PageJpaController(emf);
}

@Override
protected EntityManager getEntityManager() {
    return emf.createEntityManager();
}

@Override
public void create(Page entity) {
    controller.create(entity);
    log.info("..persisted!");
}

@Override
public void edit(Page entity) {
   controller.edit(entity);
}
....

如何从Facade调用PageJpaController.create？

1 个答案: