public static ClassLoader getAppClassLoader(final ClassLoader extcl)
            throws IOException
        {

  {- -------------------------------------------
  (1) (変数宣言など)
      (s は, クラスパス)
      ---------------------------------------- -}

                final String s = System.getProperty("java.class.path");
                final File[] path = (s == null) ? new File[0] : getClassPath(s);

  {- -------------------------------------------
  (1) java.security.AccessController.doPrivileged() を用いて, 
      特権付きの AppClassLoader インスタンスを生成し, 
      返値としてリターンする
      (なお, この AppClassLoader のパスは, 上記の System.getProperty("java.class.path") により取得したクラスパス)
      ---------------------------------------- -}

                // Note: on bugid 4256530
                // Prior implementations of this doPrivileged() block supplied
                // a rather restrictive ACC via a call to the private method
                // AppClassLoader.getContext(). This proved overly restrictive
                // when loading  classes. Specifically it prevent
                // accessClassInPackage.sun.* grants from being honored.
                //
                return AccessController.doPrivileged(
                    new PrivilegedAction<AppClassLoader>() {
                        public AppClassLoader run() {
                        URL[] urls =
                            (s == null) ? new URL[0] : pathToURLs(path);
                        return new AppClassLoader(urls, extcl);
                    }
                });
            }