code: public static ClassLoader getClassLoader(Class<?> clazz) {
          ClassLoader loader = Thread.currentThread().getContextClassLoader();
          if (loader != null) {
              return loader;
          }
          if (clazz != null) {
              loader = clazz.getClassLoader();
              if (loader != null) {
                  return loader;
              }
          }
          return ClassLoader.getSystemClassLoader();
      }
docs: 得到当前ClassLoader
  
  @param clazz 某个类
  @return ClassLoader