code: @Override
  	protected Class<?> findClass(final String name) throws ClassNotFoundException {
  		log.trace("findClass:" + name);
  		Class<?> clazz = findLoadedClass(name);
  		if (clazz != null) {
  			return clazz;
  		}
  		return super.findClass(name);
  	}
docs: 查找类,这个方法一般多用于依赖类的查找,如果之前已经加载过,则重复加载会报错,所以需要添加findLoadedClass判断