Bereich aus Quellcode auslesen - 403

import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
 
public class IdGenerator {
  public static void main(String[] args) { 
    IdGenerator meinScanner = new IdGenerator();
    String quellcode = meinScanner.fetchPage(); //du hast den Quellcode in einer Variable  
    int anfang = quellcode.indexOf("address" );
    int ende = quellcode.indexOf("adr" );    //Jetzt hole den String aus dem Quellcode
    String gesuchterText = quellcode.substring(anfang, ende);
    JOptionPane.showMessageDialog(null,gesuchterText);
  }
  public String fetchPage(){ //(String url)    
    StringBuilder sb = new StringBuilder();   
    try{
      URL url = new URL("http://...");
      URLConnection conn = url.openConnection();
      conn.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:43.0) Gecko/20100101 Firefox/43.0");
      conn.addRequestProperty("Connection", "keep-alive");     
      Scanner scanner = new Scanner(url.openConnection().getInputStream());
      while (scanner.hasNextLine()) 
      {
        sb.append(scanner.nextLine() + "\n");
      }
      scanner.close();
    } catch (MalformedURLException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return sb.toString();    
  }// fetchPage
}