code: private void readConfig() {
          //避免循环引用，Log初始化的时候不使用相关工具类
          InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("logging.properties");
          if (null == in) {
              System.err.println("not found logging.properties, use internal config!");
              return;
          }
  
          try {
              LogManager.getLogManager().readConfiguration(in);
          } catch (Exception e) {
              e.printStackTrace();
              try {
                  LogManager.getLogManager().readConfiguration();
              } catch (Exception e1) {
                  e.printStackTrace();
              }
          } finally {
              if (in != null) {
                  try {
                      in.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
          }
      }
docs: 读取ClassPath下的logging.properties配置文件