code: public static String getAbsolutePath(String classPath) {
          URL configUrl = Thread.currentThread().getContextClassLoader().getResource(classPath.substring(1));
          if (configUrl == null) {
              configUrl = ResourceUtil.class.getResource(classPath);
          }
          if (configUrl == null) {
              return null;
          }
          try {
              return configUrl.toURI().getPath();
          } catch (URISyntaxException e) {
              throw new RuntimeException(e);
          }
      }
docs: Get absolute path in file system from a classPath. If this resource not exists, return null.