对Spring中注解怎么实现的一些基本原理

package org.springframework.context; import java.io.File; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import org.dom4j.Document; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.springframew0rk.context.Autowired; import org.springframew0rk.context.Controller; import org.springframew0rk.context.Repository; import org.springframew0rk.context.Service; import com.spring.service.StudentService; public class AnnotationXmlApplicationContext implements ApplicationContext { private Map<String , Object> map0 = new HashMap<String,Object>(); //存放(id,class产生的对象) public AnnotationXmlApplicationContext(String xml){ try { this.parse(xml); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void parse(String xml) throws Exception{ // TODO Auto-generated method stub SAXReader sx = new SAXReader(); Document doc = sx.read(new File("src/"+xml)); Element ele = doc.getRootElement(); Element com = ele.element("component-scan"); String packname = com.attributeValue("base-package"); String realpackname = packname.replaceAll("\\.", "/"); File file = new File("src/"+realpackname); componentscan(file.listFiles());//扫描所有的类 discan(map0); } //扫描所有类后，对其方法进入注入 private void discan(Map<String, Object> map02) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException { // TODO Auto-generated method stub for(Object obj : map02.values()){ //得到map中的所有值 Class c = obj.getClass(); //查找方法，哪个方法有@Autowired Method[] ms = c.getMethods(); for(Method m : ms){ //setSS(StudentService ss); if(m.getAnnotation(Autowired.class)!=null){ //找到要注入的方法后，再找到方法中要注入的类型 Class cc = m.getParameterTypes()[0]; System.out.println(cc); //在map中找到和这个类型匹配的进行注入 for(Object o : map02.values()){ Class clazz[] = o.getClass().getInterfaces(); if(clazz.length != 0){ if(cc == clazz[0]){//因为方法中的参数是接口，所以我们要找到注入对象的接口相匹配的 m.invoke(obj, new Object[]{o}); } } } } } } } //扫描所有的组件,即扫描所有指定包下面的类 private void componentscan(File[] files) throws Exception { // TODO Auto-generated method stub for(File file : files){ if(file.isFile()){ String filePath = file.getPath(); //得到类的全路径 String path = filePath.substring(4).split("\\.")[0].replaceAll("\\\\", "\\."); Class c = Class.forName(path); if(c.getAnnotation(Service.class)!=null || c.getAnnotation(Controller.class)!=null || c.getAnnotation(Repository.class)!=null ){ Object obj = c.newInstance(); //产生一个实例 ，加入到map中 String id = c.getSimpleName().substring(0,1).toLowerCase()+c.getSimpleName().substring(1); map0.put(id, obj); } }else{ componentscan(file.listFiles()); } } } @Override public Object getBean(String id) { // TODO Auto-generated method stub return map0.get(id); } public static void main(String[] args) { new AnnotationXmlApplicationContext("spring_annotation.xml"); } }