尽可能地优化BillBB, BillDAO, BillEO

现在还有个缺陷就是每次都要new一个BillDAO来执行，而且在BillDAO中每次都要生成一个emf，然后又emf.close()。

明天要完善一下！

BillBB:

/*

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*/

package com.pz.backing;

import com.pz.dao.BillDAO;

import com.pz.entity.BillEO;

import java.util.List;

import javax.faces.component.UIComponent;

import javax.faces.component.html.HtmlInputText;

import javax.faces.event.ActionEvent;

/**

*

* @author bache

public class BillBB {

        private List<BillEO> billEOs;

        public void act_Add(ActionEvent e) {

                UIComponent comp = e.getComponent().getParent();

                int id = Integer.parseInt(((HtmlInputText) comp.findComponent("id")).getValue().toString());

                BillEO billEO = new BillEO();

                billEO.setId(id);

                add(billEO);

        }

        public List<BillEO> getBillEOs() {

                flushList();

                return billEOs;

        public void setBillEOs(List<BillEO> billEOs) {

                this.billEOs = billEOs;

                reset();

        private void add(BillEO billEOs) {

                new BillDAO().add(billEOs);

        private void flushList() {

                if(billEOs == null){

                        billEOs = new BillDAO().findAll();

                }

        private void reset(){

                billEOs = null;

}

BillDAO:

package com.pz.dao;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.Persistence;

import javax.persistence.PersistenceUnit;

import javax.persistence.Query;

public class BillDAO {

        List<BillEO> billEOs;

        private EntityManager em;

        @PersistenceUnit(unitName="JPAtestPU")

        private EntityManagerFactory emf;

        public void add(BillEO billEOs) {

                em = getEntityManager();

                em.getTransaction().begin();

                em.persist(billEOs);

                em.getTransaction().commit();

                em.close();emf.close();

        private EntityManager getEntityManager(){

                if(null == emf){

                        emf = Persistence.createEntityManagerFactory("JPAtestPU");

                return emf.createEntityManager();

        public List<BillEO> findAll(){

                Query query = em.createQuery("SELECT b FROM BillEO b");

                billEOs = query.getResultList();

                em.close();

                emf.close();