code: public Set<Class<?>> scan() {
  		for (URL url : ResourceUtil.getResourceIter(this.packagePath)) {
  			switch (url.getProtocol()) {
  			case "file":
  				scanFile(new File(URLUtil.decode(url.getFile(), this.charset.name())), null);
  				break;
  			case "jar":
  				scanJar(URLUtil.getJarFile(url));
  				break;
  			}
  		}
  		
  		if(CollUtil.isEmpty(this.classes)) {
  			scanJavaClassPaths();
  		}
  		
  		return Collections.unmodifiableSet(this.classes);
  	}
docs: 扫描包路径下满足class过滤器条件的所有class文件
  
  @return 类集合