HttpURLConnection 사용시 http ~ https 간의 리다이렉션 처리

HttpURLConnection을 이용하여 요청을 처리하는데, 이 URL이 http -> https 나 https -> http로 리다이렉션 되는 경우 넘겨받는 InputStream에 원하는 결과가 들어있지 않다.

다음은 http - https 간의 리다이렉션을 처리하여 InputStream을 넘겨주는 코드이다.

출처 : http://docs.oracle.com/javase/1.4.2/docs/guide/deployment/deployment-guide/upgrade-guide/article-17.html

private InputStream openConnectionCheckRedirects(URLConnection c) throws IOException
{
   boolean redir;
   int redirects = 0;
   InputStream in = null;
   do
   {
      if (c instanceof HttpURLConnection)
      {
         ((HttpURLConnection) c).setInstanceFollowRedirects(false);
      }
      // We want to open the input stream before getting headers
      // because getHeaderField() et al swallow IOExceptions.
      in = c.getInputStream();
      redir = false;
      if (c instanceof HttpURLConnection)
      {
         HttpURLConnection http = (HttpURLConnection) c;
         int stat = http.getResponseCode();
         if (stat >= 300 && stat <= 307 && stat != 306 &&
            stat != HttpURLConnection.HTTP_NOT_MODIFIED)
         {
            URL base = http.getURL();
            String loc = http.getHeaderField("Location");
            URL target = null;
            if (loc != null)
            {
               target = new URL(base, loc);
            }
            http.disconnect();
            // Redirection should be allowed only for HTTP and HTTPS
            // and should be limited to 5 redirections at most.
            if (target == null || !(target.getProtocol().equals("http")
               || target.getProtocol().equals("https"))
               || redirects >= 5)
            {
               throw new SecurityException("illegal URL redirect");
            }
            redir = true;
            c = target.openConnection();
            redirects++;
         }
      }
   }
   while (redir);
   return in;
}