ByteArrayIn/OutputStream

[Jase Jones]

Hi, I want to save a BufferedImage to hard disk, as well as transmission across a network. Since it isn't serializable I want to shove it into a byte array using the ByteArrayOutputStream, and read it back as a ByteArrayInputStream. I tried simply using ImageIcon instead, but the file-size is very large when I serialize it.

Anyways, I was stuck and found some sample code a nice guy called Christen posted called "WrapBufferedImage". I wrote a test harness around it and tested it but can't get it to work correctly. I now believe I understand it, and could write it from scratch myself, but I cannot see the flaw in it so feel it would be a waste of time until I can get this to work.

The test harness loads a picture into a JFrame, and saves this image as a byte array from a BufferedImage. Then you click the LoadBack button and it is supposed load the saved file back into a BufferedImage and display it. Unfortunately it only displays about 5% of the image, and the rest looks corrupt. I did a System.out.print of the byte array immediately after it was created and everything seems fine, but when I do the same as soon as it's loaded back, 95% of the array are zeroes.

So I can presume that either the array isn't saving correctly (though as I say, its being created fine), or the data is on the hard disk ok, it just isn't loading it back fully.

I'll post the code, the main class here is the WrapBufferedImage, whereas the test harness is MyFrame. If anyone could just paste this into their editor and have a quick look it'd be great. This has been frying my head for a week now.

Thanks in advance.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.filechooser.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.imageio.*;
import java.awt.image.BufferedImage;
 
public class MyFrame extends JFrame
{
ImageIcon icon;
boolean bool;
JFileChooser fc;
BufferedImage bimage;
String imname = "ImageNameHere.jpg";
    
public static void main(String [] args)
{
MyFrame frame = new MyFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(700, 700);
frame.setLocation(100,100);
frame.setVisible(true);
}
 
public MyFrame()
{
fc = new JFileChooser();
 bool=false; 
 bimage = null;
 
JPanel panel = new JPanel()
{
public void paintComponent(Graphics g)
{
  if(bool)
  {
 Dimension d = getSize();
 g.drawImage(icon.getImage(), 0, 0, d.width, d.height, null);
 setOpaque( false ); 
  }
  else
  {
  setOpaque( true ); 
  }
   
}
};
panel.setBackground(Color.RED);
 
JButton button = new JButton( "Load " + imname );
button.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){
                                                                       loadImage();
                                       }});
   
JButton button1 = new JButton( "Clear Window" );

button1.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){
bool = false;
repaint();
}});
JButton button2 = new JButton( "Load ByteArray" );
   
button2.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){
loadFromFile();
}});   


panel.add( button );
panel.add( button1 );
panel.add( button2 ); 
getContentPane().add(panel);
}

public void loadImage()
{
    try{
    File pic = new File(imname);
    bimage = ImageIO.read(pic);}catch(IOException e){System.out.println(":-(");}

    Image image = new ImageIcon(bimage).getImage();

    icon = new ImageIcon(image);    
    
    bool=true;
    repaint();
    
try{
ObjectOutputStream oos;
      File theFile = new File("MyBufferedImage.buf");
      
oos = new ObjectOutputStream( new FileOutputStream(theFile));
WrapBufferedImage wbi = new WrapBufferedImage();
    wbi.setIm(bimage);    
    
    wbi.writeObject(oos);
}
catch (IOException e)  { System.out.println("IOEx");}    
}

public void loadFromFile()
{
WrapBufferedImage wbi=null;

try{
ObjectInputStream ois;
      File theFile = new File("MyBufferedImage.buf");
      
ois = new ObjectInputStream( new FileInputStream(theFile));
wbi = new WrapBufferedImage();    
    
    wbi.readObject(ois);
}
catch (IOException e)  { System.out.println("IOEx");} 
catch (ClassNotFoundException e)  { System.out.println("CNFEx");} 
 
bimage = wbi.getIm();
    
    icon = new ImageIcon(bimage);
    
    bool=true;
    repaint();
}
}
 
class WrapBufferedImage implements Serializable{

private BufferedImage im = null;

public WrapBufferedImage() {
super();
}

public BufferedImage getIm() {
return im;
}
 
public void setIm(BufferedImage im) {
this.im = im;
}

    private BufferedImage fromByteArray(byte[] imagebytes) {
        try {
            if (imagebytes != null && (imagebytes.length > 0)) {
            System.out.println("We're Here");
                BufferedImage im = ImageIO.read(new ByteArrayInputStream(imagebytes));
                return im;
            }
            return null;
        } catch (IOException e) 
        {
            throw new IllegalArgumentException(e.toString());
        }
    }    
    
    private byte[] toByteArray(BufferedImage o) {
        if(o != null) {
            BufferedImage image = (BufferedImage)o;
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            try {
                ImageIO.write(image, "jpeg", baos);
            } catch (IOException e) {
                throw new IllegalStateException(e.toString());
            }
            byte[] b = baos.toByteArray();
            return b;
        }
        return new byte[0];
    }
    
    public void writeObject(java.io.ObjectOutputStream out)throws IOException 
    {
    byte[] b = toByteArray(im);
    out.writeInt(b.length);
    out.write(b);
    }

    public void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException 
    {    
    int length = in.readInt();
    byte[] b = new byte[length];    
    in.read(b);    
    im = fromByteArray(b);
    }
}

[James Carman]

Try closing your output stream when you write the object out. I didn't see where you were closing the stream.

[Jase Jones]

Thanks for the advice,

I tagged on

 out.close() 

in WrapBufferedImage, but there wasn't a difference unfortunately.

[James Carman]

I wouldn't close your stream in your writeObject() method. I'd close it after you call it...

  
wbi.writeObject(oos);
oos.close();

That, however, won't solve your problem. Make sure it's actually filling up your byte array when you read in the data from your file. The read method returns an integer indicating how many bytes it actually read. That should be equal to your length, right?

[Jase Jones]

Good point, and this does seem wierd.

I changed the

read(byte[])
to
read(byte[], offset, length)

where the length should be 86409, but the return value from read(..) is 1020. This would definately seem to be the problem. Do you think its a problem in the save section?
But I don't see how it would be reading only 1020 bytes if I'm specifically supplying 86409?, but at the same time, I can't see any problem in the save section either?

[Jase Jones]

I just threw the byte array into a basic class, saved the object to HDD, and it worked fine. Should have just done that from the start.

Thanks.