示例：
属性文件：beans.properties
articleDao=cn.com.leadfar.cms.backend.dao.impl.ArticleDaoImpl
channelDao=cn.com.leadfar.cms.backend.dao.impl.ChannelDaoImpl
使用此属性时类的配置如下：
PropertiesBeanFactory.java
package cn.com.leadfar.cms.utils;import java.io.IOException;import java.util.Properties;import cn.com.leadfar.cms.backend.dao.ArticleDao;import cn.com.leadfar.cms.backend.dao.ChannelDao;public class PropertiesBeanFactory implements BeanFactory {Properties props = new Properties();public PropertiesBeanFactory(){//读取配置文件，得到具体DAO的实现类名try {props.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("beans.properties"));} catch (IOException e) {e.printStackTrace();}}public ArticleDao getArticleDao() {String className = props.getProperty("articleDao");try {Class clz = Class.forName(className);return (ArticleDao)clz.newInstance();} catch (ClassNotFoundException e) {e.printStackTrace();} catch (InstantiationException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}return null;}public ChannelDao getChannelDao() {String className = props.getProperty("channelDao");try {Class clz = Class.forName(className);return (ChannelDao)clz.newInstance();} catch (ClassNotFoundException e) {e.printStackTrace();} catch (InstantiationException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}return null;}}
