模仿spring 获取dao
public final class BeanFactory {private static Map<String,Object> map = null;static {load();}public static Object getBean(String beanName) {return map.get(beanName);}public static void load() {map = new HashMap<String,Object>();try {Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(Thread.currentThread().getContextClassLoader().getResource("beanfactory.xml").getPath());NodeList daos = doc.getElementsByTagName("bean");Element e=null;int length=daos.getLength();for (int i = 0; i < length; i++) {e = (Element) daos.item(i);map.put(e.getAttribute("name"), Class.forName(e.getAttribute("class")).newInstance());}e=null;daos=null;doc=null;} catch (Exception ex) {ex.printStackTrace();}}}