code: public static ApplicationClassLoader getJarApplicationClassLoader(String jarFilePath) {
          ApplicationClassLoader jarApplicationClassLoader = jarApplicationClassLoaderCache.get(jarFilePath);
          if (jarApplicationClassLoader != null) {
              return jarApplicationClassLoader;
          }
          synchronized (jarApplicationClassLoaderCache) {
              jarApplicationClassLoader = jarApplicationClassLoaderCache.get(jarFilePath);
              if (jarApplicationClassLoader != null) {
                  return jarApplicationClassLoader;
              }
              jarApplicationClassLoader = new ApplicationClassLoader(nodeApplicationClassLoader, false);
              jarApplicationClassLoader.addJarFiles(jarFilePath);
              jarApplicationClassLoaderCache.put(jarFilePath, jarApplicationClassLoader);
              return jarApplicationClassLoader;
          }
      }
docs: 获取jar包对应的类加载器,对于一个固定的jar包来说,该类加载器唯一
  
  @param jarFilePath jar包的本地文件路径
  @return jar包对应的类加载器