fatory的模拟

package com.wenwen.drp.beanfactory;import java.util.HashMap;import java.util.Map;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.io.SAXReader;import com.wenwen.drp.basedata.dao.ItemDao;import com.wenwen.drp.basedata.manager.ItemManager;public class BeanFactory {/* *装下所用的dao对象 * */ private Map daoMap = new HashMap(); /*  * 装下所有的service对象  * */ private Map serviceMap = new HashMap(); private static BeanFactory factory = new BeanFactory(); private final String config_file="bean_config.xml"; private Document doc; /*  * 初始化时将bean_config.xml读取到内存当中  * */public BeanFactory(){SAXReader reader=new SAXReader();try {doc = reader.read(Thread.currentThread().getContextClassLoader().getResourceAsStream(config_file));} catch (DocumentException e) {e.printStackTrace();}}/* * 单例化创建工厂 * */public static BeanFactory newInstanse(){return factory;}/* * 拿到dao的完全路径，反射机制创建对象 * *////Element beanElt = (Element)doc.selectSingleNode("//service[@id=\"" + serviceId + "\"]");public Object getInstanceDao(String daoId){Object dao = null;//若daoMap中存在daoId,说明已经有了这个dao,则直接返回这个daoMap即可if(daoMap.containsKey("daoId"))return daoMap;Element elt = (Element) doc.selectSingleNode("//dao[@id=\""+daoId+"\"]");String className = elt.attributeValue("class");try {dao=Class.forName(className).newInstance();daoMap.put(daoId, dao);} catch (Exception e) {e.printStackTrace();}//将创建好多的对象放到Map中return dao;}/* * 创建mservice * */public Object getInstanceService(String serviceId){Object service = null;//若serviceMap中存在serviceId,说明已经有了这个service,则直接返回这个serviceMap即可if(serviceMap.containsKey("serviceId"))return serviceMap;Element elt = (Element) doc.selectSingleNode("//service[@id=\""+serviceId+"\"]");String className = elt.attributeValue("class");try {service=Class.forName(className).newInstance();serviceMap.put(serviceId, service);} catch (Exception e) {e.printStackTrace();}//将创建好多的对象放到Map中return service;}public static void main(String[] args){ItemDao itemdao = (ItemDao) factory.newInstanse().getInstanceDao("itemdao");System.out.println(itemdao);ItemManager manager = (ItemManager) factory.newInstanse().getInstanceService("itemManager");System.out.println(manager);}}

<?xml version="1.0" encoding="UTF-8"?><bean><dao id="itemdao" class="com.wenwen.drp.basedata.dao.Dao4OracleImpl"/><service id="itemManager" class="com.wenwen.drp.basedata.manager.ItemManager"/></bean>