code: public InputStream getInputStream(String innerPath) throws IOException {
          JarEntry entry = file.getJarEntry(innerPath);
          if( entry == null )
              throw new IllegalArgumentException("Can't find " + innerPath + " from " + file.getName());
          //class loader可能还没有正确配置好,此时直接从file里面获取
          try {
              return super.getResource(innerPath).getInputStream();
          } catch (IOException e) {
              return file.getInputStream(entry);
          }
      }
docs: //////////////////////////////////////////////////////////////////////////////////////////////////////////