code: public static boolean isUrl(CharSequence value) {
  		try {
  			new java.net.URL(StrUtil.str(value));
  		} catch (MalformedURLException e) {
  			return false;
  		}
  		return true;
  	}
docs: 验证是否为URL
  
  @param value 值
  @return 是否为URL