Untitled

import java.io.*;
import java.util.jar.JarOutputStream;
import java.util.jar.Pack200;
import java.util.zip.GZIPInputStream;

public class RSUnpacker
{

    public RSUnpacker()
    {
    }

    public static final void main(String args[])
    {
        if(args.length < 2)
        {
            System.out.println("Usage: RSUnpacker [input] [output]");
            System.out.println("Eg: RSUnpacker runescape.pack200 runescape.jar");
            System.exit(2);
        }
        byte abyte0[] = readfile(args[0]);
        byte abyte1[] = new byte[abyte0.length + 2];
        abyte1[0] = 31;
        abyte1[1] = -117;
        System.arraycopy(abyte0, 0, abyte1, 2, abyte0.length);
        try
        {
            FileOutputStream fileoutputstream = new FileOutputStream(args[1]);
            JarOutputStream jaroutputstream = new JarOutputStream(fileoutputstream);
            java.util.jar.Pack200.Unpacker unpacker = Pack200.newUnpacker();
            unpacker.unpack(new GZIPInputStream(new ByteArrayInputStream(abyte1)), jaroutputstream);
            jaroutputstream.close();
            System.out.println((new StringBuilder()).append("Extracted ").append(args[0]).append(" to: ").append(args[1]).toString());
        }
        catch(IOException ioexception)
        {
            ioexception.printStackTrace();
        }
    }

    public static final byte[] readfile(String s)
    {
        File file = new File(s);
        if(!file.exists())
        {
            return null;
        }
        byte abyte0[];
        int i = (int)file.length();
        abyte0 = new byte[i];
        try {
           DataInputStream datainputstream = new DataInputStream(new BufferedInputStream(new FileInputStream(s)));
           datainputstream.readFully(abyte0, 0, i);
           datainputstream.close();
           return abyte0;
        } catch (Throwable throwable){
           throwable.printStackTrace();
        }
        return null;
    }
}