1: 首先我们要利用dom4j进行xml的解析，将所有的bean的配置读取出来。

2：利用java的反射机制进行对象的实例化。

3： 直接获得对象

 

package cn.Junit.test;import java.net.URL;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.dom4j.Document;import org.dom4j.Element;import org.dom4j.XPath;import org.dom4j.io.SAXReader;import org.springframework.beans.factory.config.BeanDefinition;public class MyClassPathXmlApplicationContext {	private String filemame;	private List
     
       list = new ArrayList
      
       ();	private Map
       
         singletons = new HashMap
        
         ();	public MyClassPathXmlApplicationContext() {		super();		// TODO Auto-generated constructor stub	}	public MyClassPathXmlApplicationContext(String filemame) {		//1. 读取XML配置文件		this.readXML(filemame);		//2.实例化对象		this.instanceBean();	}	private void instanceBean() {		for (DefBean bean : list) {			try {				singletons.put(bean.getId(), Class.forName(bean.getClassName()).newInstance());			} catch (Exception e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}	}	private void readXML(String filemame) {		SAXReader saxReader = new SAXReader();		Document document = null;		try {			URL xmlpath = this.getClass().getClassLoader()					.getResource(filemame);			document = saxReader.read(xmlpath);						Map
         
           nsMap = new HashMap
          
           (); nsMap.put("ns", "http://www.springframework.org/schema/beans");// 加入命名空间 XPath xsub = document.createXPath("//ns:beans/ns:bean");// 创建beans/bean查询路径 xsub.setNamespaceURIs(nsMap);// 设置命名空间 List
           
             beans = xsub.selectNodes(document);// 获取文档下所有bean节点 for (Element element : beans) { String id = element.attributeValue("id");// 获取id属性值 String clazz = element.attributeValue("class"); // 获取class属性值 DefBean bean = new DefBean(id, clazz); list.add(bean); } } catch (Exception e) { e.printStackTrace(); } } //3. 获得bean对象 public Object getBean(String key) { return singletons.get(key); }}