短链接变长链接

public void Test() throws IOException {
   HttpURLConnection conn = (HttpURLConnection) new java.net.URL("https://v.douyin.com/NBnULu2")
         .openConnection();
   conn.setInstanceFollowRedirects(false);
   conn.setConnectTimeout(5000);
   String url = conn.getHeaderField("Location");
   
   System.out.println(url);
}