知识大全简单模拟spring的容器管理bean

Posted 2022-07-18 知

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package spring;import java io IOException;import URL;import java util ArrayList;import java util HashMap;import java util List;import java util Map;import jdom Document;import jdom Element;import jdom JDOMException;import jdom input SAXBuilder;import jdom xpath XPath;import vo BeanDefinition;/** * 简单模拟spring的ClassPathXmlApplicationContext spring容器管理bean * * @author zdw * */@SuppressWarnings( unchecked )public class MyApplicationContext private List<BeanDefinition> list = new ArrayList<BeanDefinition>(); private Map<String Object> sigletons = new HashMap<String Object>(); public MyApplicationContext(String fileName) this readXML(fileName); try instanceBeans(); catch (Exception e) e printStackTrace(); /** * 实例化所有bean * * @throws InstantiationException * @throws IllegalAccessException * @throws ClassNotFoundException */ private void instanceBeans() throws InstantiationException IllegalAccessException ClassNotFoundException for (BeanDefinition bean : list) if (null != bean getClassName() && bean getClassName() length() > ) sigletons put(bean getId() Class forName(bean getClassName()) newInstance()); /** * 读取xml配置 * * @param fileName */ public void readXML(String fileName) SAXBuilder builder = new SAXBuilder(); URL url = this getClass() getClassLoader() getResource(fileName); try Document doc = builder build(url); XPath xpath = XPath newInstance( //ns:beans/ns:bean ); xpath addNamespace( ns ); List<Element> beans = xpath selectNodes(doc); for (Element bean : beans) String id = bean getAttributeValue( id ); String className = bean getAttributeValue( class ); BeanDefinition beanDefinition = new BeanDefinition(id className); list add(beanDefinition); catch (JDOMException e) e printStackTrace(); catch (IOException e) e printStackTrace(); /** * 得到指定id的bean * * @param id * @return */ public Object getBean(String id) return sigletons get(id);

　　测试

@Test public void testMyUserService() MyApplicationContext ctx = new MyApplicationContext( beans xml ); UserService us = (UserService) ctx getBean( userService ); us print(); cha138/Article/program/Java/ky/201311/28759

知识大全 简单模拟spring的容器管理bean

知识大全简单模拟spring的容器管理bean