Extracting Image From A Jar File

[Ashik Uzzaman]

Dear Pals,
I followed the tutorial provided in JavaWorld to to Extract an Image from a JAR File
But in the middle, I am in problem.

 
package jarTest;
import java.io.*;
import java.util.*;
import java.util.zip.*;
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
public final class JarResources {
   public boolean debugOn=false;
   private Hashtable htSizes=new Hashtable();
   private Hashtable htJarContents=new Hashtable();
   private String jarFileName;
   public JarResources(String jarFileName) {
      this.jarFileName=jarFileName;
      init();
   }
   public byte[] getResource(String name) {
      return (byte[])htJarContents.get(name);
   }
   private void init() {
      try {
          // extracts just sizes only.
          ZipFile zf=new ZipFile(jarFileName);
          Enumeration e=zf.entries();
          while (e.hasMoreElements()) {
              ZipEntry ze=(ZipEntry)e.nextElement();
              if (debugOn) {
                 System.out.println(dumpZipEntry(ze));
              }
              htSizes.put(ze.getName(),new Integer((int)ze.getSize()));
          }
          zf.close();
          // extract resources and put them into the hashtable.
          FileInputStream fis=new FileInputStream(jarFileName);
          BufferedInputStream bis=new BufferedInputStream(fis);
          ZipInputStream zis=new ZipInputStream(bis);
          ZipEntry ze=null;
          while ((ze=zis.getNextEntry())!=null) {
             if (ze.isDirectory()) {
                continue;
             }
             if (debugOn) {
                System.out.println(
                   "ze.getName()="+ze.getName()+","+"getSize()="+ze.getSize()
                   );
             }
             int size=(int)ze.getSize();
             // -1 means unknown size.
             if (size==-1) {
                size=((Integer)htSizes.get(ze.getName())).intValue();
             }
             byte[] b=new byte[(int)size];
             int rb=0;
             int chunk=0;
             while (((int)size - rb) > 0) {
                 chunk=zis.read(b,rb,(int)size - rb);
                 if (chunk==-1) {
                    break;
                 }
                 rb+=chunk;
             }
             // add to internal resource hashtable
             htJarContents.put(ze.getName(),b);
             if (debugOn) {
                System.out.println(
                   ze.getName()+"  rb="+rb+
                   ",size="+size+
                   ",csize="+ze.getCompressedSize()
                   );
             }
          }
       } catch (NullPointerException e) {
          System.out.println("done.");
       } catch (FileNotFoundException e) {
          e.printStackTrace();
       } catch (IOException e) {
          e.printStackTrace();
       }
   }
   private String dumpZipEntry(ZipEntry ze) {
       StringBuffer sb=new StringBuffer();
       if (ze.isDirectory()) {
          sb.append("d ");
       } else {
          sb.append("f ");
       }
       if (ze.getMethod()==ZipEntry.STORED) {
          sb.append("stored   ");
       } else {
          sb.append("defalted ");
       }
       sb.append(ze.getName());
       sb.append("\t");
       sb.append(""+ze.getSize());
       if (ze.getMethod()==ZipEntry.DEFLATED) {
          sb.append("/"+ze.getCompressedSize());
       }
       return (sb.toString());
   }
   public static void main(String[] args) throws IOException {
       new DisplayApp();
   }
}// End of JarResources class.
class DisplayApp extends JFrame {
JarResources JR;
Image image, logo;
public DisplayApp () {
JR = new JarResources("allImages.jar");
                System.out.println(JR.toString() + " --- ashik 1");
logo = (Image) Toolkit.getDefaultToolkit().createImage( JR.getResource("ashik.jpg") );
                System.out.println(logo.toString() + " --- ashik 2");
                MyCanvas c = new MyCanvas(logo);
JButton jb = new JButton("Hello", new ImageIcon(logo));
                JButton jb2 = new JButton("Southern", new ImageIcon("scjplogo.gif"));
this.getContentPane().add(jb, BorderLayout.CENTER);
                this.getContentPane().add(jb2, BorderLayout.NORTH);
                this.getContentPane().add(c, BorderLayout.SOUTH);
this.setBounds(20,20,400,400);
this.setVisible(true);
}
}
class MyCanvas extends Canvas {
    private Image img;
    
    public MyCanvas(Image i) {
        img = i;
        this.setBackground(Color.green);
    }
    public void paint(Graphics g) {
        g.drawImage(img,70,70,null);
    }
}

I am seeing the button in the north with image, but the center button is without image and the canvas is totally not displayed. I am expecting the center "Hello" button display an imageicon. My comannd line displays the following
jarTest.JarResources@784386 --- ashik 1 and
sun.awt.windows.WImage@171afc --- ashik 2
Waiting for your response on where did I miss?
:roll:

[Nathan Pruett]

I got your code to work with some small modifications... I'm not sure why your second image isn't displaying. Is there anything special about the images you are trying to display? All the images I displayed from the JAR file displayed correctly... make sure file names are correct, and that the image isn't corrupted.

As far as why the canvas isn't showing up... the default size of a Canvas is 0x0, so just change it to something large enough to display the image in the constructor. (Also, it's a bad idea to mix AWT components like Canvas with Swing components... you will run into problems down the road...)

[Ashik Uzzaman]

Dear Nate,
I am also where I am mistaking...Would you like to mail me your .java file and the .class file at [e-mail]? I would be very pleased to you...

[Nathan Pruett]

The only thing I changed in the JAR reading part were the names of the images and the JAR file...

But I'll go ahead and post the code I have now...

package jarTest;
 
import java.io.*;
import java.util.*;
import java.util.zip.*;
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
 
public final class JarResources {
    
    public boolean debugOn = false;
    private Hashtable htSizes = new Hashtable();
    private Hashtable htJarContents = new Hashtable();
    private String jarFileName;
    
    public JarResources( String jarFileName ) {
        this.jarFileName=jarFileName;
        init();
    }
    
    public byte[] getResource( String name ) {
        return (byte[])htJarContents.get( name );
    }
    
    private void init() {
        try {
            // extracts just sizes only.
            ZipFile zf=new ZipFile( jarFileName );
            Enumeration e = zf.entries();
            while ( e.hasMoreElements() ) {
                ZipEntry ze=(ZipEntry)e.nextElement();
                if ( debugOn ) { 
                    System.out.println( dumpZipEntry( ze ) );
                }
                htSizes.put( ze.getName(), new Integer( (int)ze.getSize() ) );
            }
            zf.close();
            
            // extract resources and put them into the hashtable.
            FileInputStream fis = new FileInputStream( jarFileName );
            BufferedInputStream bis=new BufferedInputStream( fis );
            ZipInputStream zis = new ZipInputStream( bis );
            ZipEntry ze = null;
            while ( (ze = zis.getNextEntry() ) != null ) {
                if ( ze.isDirectory() ) {
                    continue;
                }
                if ( debugOn ) {
                    System.out.println(                   
                            "ze.getName()=" + ze.getName()+ "," + 
                            "getSize()=" + ze.getSize()
                    );
                }
                int size = (int)ze.getSize();
                // -1 means unknown size.
                if ( size == -1 ) {
                    size = ( (Integer)htSizes.get( ze.getName() ) ).intValue();
                }
                byte[] b = new byte[ (int)size ];
                int rb = 0;
                int chunk = 0;
                while ( ( (int)size - rb ) > 0 ) {
                    chunk = zis.read( b, rb, (int)size - rb );
                    if ( chunk == -1 ) {
                        break;
                    }
                    rb += chunk;
                }
                // add to internal resource hashtable
                htJarContents.put( ze.getName(), b );
                if ( debugOn ) {
                    System.out.println(
                            ze.getName() + "  rb=" + rb +
                            ",size=" + size +
                            ",csize=" + ze.getCompressedSize()
                    );
                }
            }
        }
        catch ( NullPointerException e ) {
            System.out.println( "done." );
        }
        catch ( FileNotFoundException e ) {
            e.printStackTrace();
        }
        catch ( IOException e ) {
            e.printStackTrace();
        }
    }
    
    private String dumpZipEntry( ZipEntry ze ) {
        StringBuffer sb = new StringBuffer();
        if ( ze.isDirectory() ) {
            sb.append( "d " );
        }
        else {          
            sb.append( "f " );
        }
        if ( ze.getMethod() == ZipEntry.STORED ) {
            sb.append( "stored   " );
        }
        else {
            sb.append( "defalted " );
        }
        sb.append( ze.getName() );
        sb.append( "\t" );
        sb.append( "" + ze.getSize() );
        if ( ze.getMethod() == ZipEntry.DEFLATED ) {
            sb.append( "/" + ze.getCompressedSize() );
        }
        return ( sb.toString() );
    }
    
    public static void main( String[] args ) throws IOException {
        new DisplayApp();
    }
}
// End of JarResources class.
 
class DisplayApp extends JFrame {  
    JarResources JR;
    Image image, logo;
    
    public DisplayApp () {
        JR = new JarResources( "test.jar" );
        System.out.println( JR.toString() + " --- badstat" );
        logo = (Image)Toolkit.getDefaultToolkit().createImage( JR.getResource( "badstat.gif" ) );
        System.out.println( logo.toString() + " --- javalogo" );
        MyCanvas c = new MyCanvas( logo );
        JButton jb = new JButton( "Hello", new ImageIcon( logo ) );
        JButton jb2 = new JButton( "Southern", new ImageIcon( "javalogo.gif" ) );
        this.getContentPane().add( jb, BorderLayout.CENTER );
        this.getContentPane().add( jb2, BorderLayout.NORTH );
        this.getContentPane().add( c, BorderLayout.SOUTH );
        this.setBounds( 20, 20, 400, 400);
        this.setVisible( true );
    }
}
 
class MyCanvas extends JPanel {
    private Image img;
    
    public MyCanvas( Image i ) {
        img = i;
        this.setBackground( Color.green );
        this.setOpaque( true );
    }
    
    public void paintComponent( Graphics g ) {
        g.drawImage( img, 70, 70, null );
    }
    
    public Dimension getPreferredSize() {
        Dimension d = super.getPreferredSize();
        if ( img != null ) {
            d = new Dimension( 70 + img.getWidth( this ), 
                    70 + img.getHeight( this ) );
        }
        return d;
    }
}

[Ashik Uzzaman]

Nate, thank you very much. Your code is running in my machine. Now I'll find out where did I make the mistake and let you know.

[Ashik Uzzaman]

Nate, thank you very much. Your code is running in my machine. Now I'll find out where did I make the mistake and let you know.