Can't get ImageIcon to show up from captcha

[Anders Kviback]

Hello!

I have an assigment were I'm supposed to validate a captcha. But I can't get the captcha image to get loaded into my GUI. I have two classes so far. First the ParsCaptcha.java class that contains the method getImage()

package Lektion4_uppgift1;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

public class ParsCaptcha {
	
	private final String content;
	
	public ParsCaptcha(String content){
		this.content = content;
	}
	
	public ImageIcon getImage() throws IOException{
		
		BufferedImage img = null;
		ImageIcon captcha = null;
		// Letar först efter texten mellan taggarna image
		// därefter plockar vi URL till bilden mellan taggarna url
		String s = getTextBetween("<image>", "</image>");
		s = getTextBetween("<url>", "</url>");

		if (s.length() == 0)
			return null;

		try
		{
			// Skapa ett URL-objekt
			URL imageURL = new URL(s);

			// Skapar en BufferedImage från URLn
			img = ImageIO.read(imageURL);
		captcha = new ImageIcon(img);
		}
		catch (MalformedURLException urlFel)
		{}
		
		return captcha;
	}
	
	// Returnera en delsträng från innehållet (content)
	private String getTextBetween(String start, String end)
	{
		return getTextBetween(content, start, end);
	}

	// Returnerar en delsträng från text som finns mellan strängarna start och end
	private String getTextBetween(String text, String start, String end)
	{
		// Om någon av strängarna refererar till null returnera tomt
		if (start == null || end == null)
			return "";

		// Tar reda på vilka index strängarna start och end finns på
		int startindex = text.indexOf(start);
		int endindex = text.indexOf(end, startindex);

		// Om något av index är -1 eller om slutindex är mindre än starindex returnera tomt
		if (startindex < 0 || endindex < 0 || endindex < startindex)
			return "";

		// Returnera strängen mellan index startindex och endindex
		return text.substring(startindex + start.length(), endindex);
	}

}

And the GUI:

package Lektion4_uppgift1;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;
import javax.swing.border.EtchedBorder;


import java.net.*;
import java.io.*;
import java.util.*;
import java.text.*;
@SuppressWarnings("serial")
public class GUICaptchaTest extends JFrame implements ActionListener{
	
	
	// Komponenter m.m.
	private URL url = new URL("http://dt066g.programvaruteknik.nu/captcha.php");
	private ParsCaptcha parser;
	private JLabel label;
	JTextField text;
	private JButton validate;
	private JMenuItem quitMenuItem;
	//private JFrame frame;
	
	public GUICaptchaTest() throws IOException{
		
		//Sätter titel på fönstret
		setTitle("Captcha validator");
		
		//Sätter storlek och placering av fönstret
		setSize(400, 480);
		setLocation(200, 200);
	
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		label = new JLabel();
		label.setEnabled(true);
		
		label.setLayout(new GridLayout(1,1));
		
		createParser();
		update();
		
		EtchedBorder e = new EtchedBorder();
		label.setBorder(e);
		add(label);
		label.setPreferredSize(new Dimension(200,200));
		System.out.println("TestKonstruktor");
		//pack();
		setVisible(true);
		
				
	}
	// ***************************************************************
	// Ta hand om ActionEvent från knapp 
	// ***************************************************************
	public void actionPerformed(ActionEvent ae){
		
		if(ae.getSource() == validate){
			createCaptcha("http://dt066g.programvaruteknik.nu/captcha.php");
		}
		else if (ae.getSource() == quitMenuItem)
		{
			System.exit(0);
		}
		createParser();
		update();
		
	}
	// ***************************************************************
	// Skapar en ny URL 
	// ***************************************************************
	private void createCaptcha(String url){
		try{
			this.url = new URL(url);
		}
		
		catch (MalformedURLException fel){
			text.setText("<b>Kunde inte skapa URL:</b>" + fel.toString());
		}
	}
	
	private void createParser(){
		
		try{
			
			BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
			StringBuffer sb = new StringBuffer();
			String s;

			while((s = in.readLine()) != null)
				sb.append(s);

			in.close();

			parser = new ParsCaptcha(sb.toString());
		}
		catch (IOException fel)
		{
			text.setText("<b>Fel vid läsning från URL:</b><br>" + fel.toString());
		}
	}
	
	private void update(){
		
		try{
		label.setIcon(parser.getImage());
		}
		catch (IOException fel)
		{
			text.setText("<b>Fel vid läsning från URL:</b><br>" + fel.toString());
		}; 
	}
	
	public static void main(String[] args) throws IOException
	{
		new GUICaptcha();
	}
}

But I can't get the image to show up in the frame that my GUI creates. At the end of the GUIconstructor I have put a system.out.println("TestKonstruktor"); just to check that the program goes through the methods. And I do get TestKonstruktor in the console. And there is n NullPointerException. The method getTextBetween returns "" if startindex is null. But with System.out.println("start:" + start); the console prints out
start:<image>
start:<url>

So, it seems to be OK there as well. Does anyone understand were to find the solution? Or, is there something with the GUI?
( I am not using the actionPerformed method right now )

Anders

[Anders Kviback]

Just after submitting I saw that in the method getTextBetween startindex and endindex do get values -1 so getTextBetween will return "". But why then do they get the values -1?

Anders

[Tina Smith]

Because of how indexOf behaves. If it can find the string, it will return the index. If it can't find the string it returns garbage data (-1), which means that the substring you're looking for doesn't exist.
What is the content of sb (line 99) and does it contain the text "<image>"?

[Anders Kviback]

Thank you for answering,

If I do a System.out.println(sb.toString()); after line 100 ie

parser = new ParsCaptcha(sb.toString());
System.out.println("sb.toString()" + sb.toString());

Nothing happens ie it doesn't seem to be a string there. ?? So , for some reason, my piece of code isn't reading what I want it to. I can't figure out what?

Anders

[Anders Kviback]

I saw a mistake here. I had the wrong class in main in the GUI class. Now I've fixed that. So, here is what I get when putting in system.out.println(sb.toString()) at createParser():

ÿØÿà a lot of squares CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), default qualityÿÛ a lot of asquares plus much more

So, there is something being read. But I'm obviously not getting the imageicon. So, am I not using the correct code to read the stream, in createPareser() ie:

uc.getInputStream();

or should I change the tags, to read inbetween, ie should it be something else instead of <image> and <url> in the getImage() method.
Or, is it something wrong in my handling in GUI?

Someone?

[Michael Dunn]

> Or, is it something wrong in my handling in GUI?

easy to test.

put an image in the same folder, then change

//label.setIcon(parser.getImage());
label.setIcon(new ImageIcon("Test.gif"));//your image name e.g test.gif

also, comment out
//createParser();

so, when run, it's only job is to set the label's icon

if image appears OK, then GUI is not the problem

[Tina Smith]

It's something fundamentally wrong with your assumption of what you are reading. It's not HTML (check the content-type of the HTTP header below).

I used Fiddler to check the content that is sent over the HTTP connection: it returned the following:

HTTP/1.1 200 OK
Date: Sun, 12 Feb 2012 22:44:56 GMT
Server: Apache/2.2.20 (FreeBSD) PHP/5.3.5 with Suhosin-Patch mod_ssl/2.2.20 OpenSSL/0.9.8q
X-Powered-By: PHP/5.3.5
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Sun, 12 Feb 2012 22:44:56 GMT
Content-Length: 6266
Connection: close
Content-Type: image/jpeg

...

[Darryl Burke]

Tina Smith wrote:It's something fundamentally wrong with your assumption of what you are reading. It's not HTML (check the content-type of the HTTP header below).

I used Fiddler to check the content that is sent over the HTTP connection: it returned the following:

HTTP/1.1 200 OK
Date: Sun, 12 Feb 2012 22:44:56 GMT
Server: Apache/2.2.20 (FreeBSD) PHP/5.3.5 with Suhosin-Patch mod_ssl/2.2.20 OpenSSL/0.9.8q
X-Powered-By: PHP/5.3.5
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Sun, 12 Feb 2012 22:44:56 GMT
Content-Length: 6266
Connection: close
Content-Type: image/jpeg

...

Hmm...

import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JOptionPane;

public class CaptchaIcon {

  public static void main(String[] args) throws Exception {
    JOptionPane.showMessageDialog(
            null, new ImageIcon(
            new URL("http://dt066g.programvaruteknik.nu/captcha.php")));
  }
}

[Anders Kviback]

Yes, the picture is there. So, the GUI is working, but this is not HTML code. I compared this to another piece of code I have were I read RSS. And in that code I saw the HTML tags. But here there are no html tags. I'm stuck. I have to read the captcha code but I do not understand how?
Anyone?

[Darryl Burke]

Did you really think you would read the captcha code from whatever the server serves up? That would defeat the very purpose of a captcha, which is to verify that a human is responding.

What exactly are you trying to achieve?

[Anders Kviback]

hello, again!

I misunderstood the assignment. The captcha was created at a server and we had to use a special webaddress to get the captcha and then to validate the captcha with another address. Thanks a lot though that you've taken you're time here. Though, I solved the assignment.

Anders