模拟Spring扫描注解类

1，编写注解类

import java.lang.annotation.Documented;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.annotation.ElementType;

@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Description {

	public String value();
}

2，扫描指定包下的所有.class结尾的类

        static List<String> list = new ArrayList<String>();
	static String packageDirName = "com.space".replace('.', '/'); 
	static StringBuffer buffer = new StringBuffer("com.space");
	public static void main(String[] args) throws IOException, ClassNotFoundException {
		 
		  
	     Enumeration<URL> dirs=Thread.currentThread().getContextClassLoader().getResources(packageDirName);  
	   
	     while(dirs.hasMoreElements()){
	    	 URL url = dirs.nextElement();
             
	         String protocol = url.getProtocol();  
	         if ("file".equals(protocol)){//文件扫描
	             String filePath = URLDecoder.decode(url.getFile(), "UTF-8"); 
	             File file = new File(filePath);
	             getClassName(file);
	         }  

	        if ("jar".equals(protocol)) {  
	            JarFile jar= ((JarURLConnection) url.openConnection()).getJarFile(); 
	            Enumeration<JarEntry> entries = jar.entries();//获取文件，需要递归处理文件夹

	        }
	     }
	     
	 
	     for(String str:list){
	    	 System.out.println(str);
	    	 Class<?> c = Class.forName(str);
	    	 boolean isAnno = c.isAnnotationPresent(Description.class);
	    	 if(isAnno){
	    		 Description d = c.getAnnotation(Description.class);
	    		 System.out.println(d.value());
	    	 }
	     }

	}
	
	public static void getClassName(File file) throws IOException{
		if(file.isDirectory()){
			File[] files =file.listFiles(new FileFilter() {
				@Override
				public boolean accept(File pathname) {
					return pathname.getName().endsWith(".class")||pathname.isDirectory();
				}
			});
			for(File f:files){
				getClassName(f);
			}
			 
		}else{
			String name =file.getAbsolutePath();
			name = name.substring(name.lastIndexOf("com\\space")).replaceAll("\\\\", ".");
			name = name.substring(0, name.lastIndexOf("."));
			list.add(name);
		}
	}

 如果大家有更好的办法可以相互学习下