January 21, 2009 12:13 PM

HostJ2ME.com uses the code below to extract application icons from Midlet jars and display them in the HostJ2ME.com midlet directory.

package com.astrientlabs.hostj2me.util;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;

import com.astrientlabs.files.AstrientFile;
import com.astrientlabs.util.Strings;

public class IconExtractor
{
    private String MANIFEST = "META-INF/MANIFEST.MF";
    
    public byte[] extract(String path) throws ZipException, IOException
    {
        return extract(new File(path));
    }
    
    public byte[] extract(File jarFile) throws ZipException, IOException
    {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
        ZipFile zipFile = new ZipFile(jarFile);
        try
        {
            /*for ( Enumeration? extends ZipEntry> e = zipFile.entries(); e.hasMoreElements(); )
            {
                System.out.println(e.nextElement().getName());
            }*/
            
            ZipEntry entry = zipFile.getEntry(MANIFEST);

            InputStream is = zipFile.getInputStream(entry);
            if ( is != null )
            {
                Properties props = new Properties();
                props.load(is);
                
                String iconFile = props.getProperty("MIDlet-Icon");
                if ( Strings.isNull(iconFile) )
                {
                    props.list(System.out);
                    String midlet1 = props.getProperty("MIDlet-1");
                    if ( !Strings.isNull(midlet1) )
                    {
                        String[] parts = midlet1.split(",");
                        if ( parts.length > 2 )
                        {
                            iconFile = parts[1].trim();
                            if ( iconFile.startsWith("/") )
                            {
                                iconFile = iconFile.substring(1);
                            }
                        }
                    }
                }
                
                if ( iconFile != null )
                {
                    ZipEntry iconEntry = zipFile.getEntry(iconFile);
                    
                    if ( iconEntry != null )
                    {
                        FileOutputStream fos = new FileOutputStream("/tmp/icon.png");
                        InputStream zis = zipFile.getInputStream(iconEntry);
                        int r = 0;
                        byte[] buffer = new byte[4*1024];
                        while( (r = zis.read(buffer)) != -1 )
                        {
                            baos.write(buffer,0,r);
                            fos.write(buffer,0,r);
                        }
                        
                        fos.close();
                        zis.close();
                    }
                }
            }    
        }
        finally
        {
            zipFile.close();    
        }
                
        return baos.toByteArray();
    }
    
    public static void main(String[] args)
    {
        
        File jarFile = new File("/projects/workspace/cliqmobile/builds/cliqmobile.jar");
        IconExtractor extractor = new IconExtractor();
        try
        {
            byte[] data = extractor.extract(jarFile);
            System.out.println(data.length + " " + AstrientFile.fileType(data));
        }
        catch (ZipException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        System.exit(0);
    }
}