FatJar.java

package com.ra4king.fatjar;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;

public class FatJar {
    public static void main(String[] args) {
        System.out.println("FatJar 1.0 by Roi Atalla (ra4king)");

        if(args.length != 8) {
            printUsage();
            return;
        }

        String libs[] = null, natives[] = null, main = null, output = null;

        for(int a = 0; a < 8; a++) {
            String s = args[a];

            if(s.length() == 0 || s.charAt(0) != '-') {
                printUsage();
                return;
            }

            s = s.toLowerCase();

            if(s.equalsIgnoreCase("-libs"))
                libs = args[++a].split(";");
            else if(s.equalsIgnoreCase("-natives"))
                natives = args[++a].split(";");
            else if(s.equalsIgnoreCase("-main"))
                main = args[++a];
            else if(s.equalsIgnoreCase("-output"))
                output = args[++a];
        }

        if(libs == null || natives == null || main == null || output == null) {
            printUsage();
            return;
        }

        Manifest manifest = new Manifest();
        Attributes attrib = manifest.getMainAttributes();
        attrib.putValue("Manifest-Version", "1.0");
        attrib.putValue("Main-Class", "com.ra4king.fatjar.FatJarLauncher");
        attrib.putValue("Launcher-Main-Class", main);

        File outputFile;
        JarOutputStream jarOS;
        try {
            outputFile= new File(output);
            outputFile.createNewFile();

            jarOS = new JarOutputStream(new FileOutputStream(outputFile), manifest);
        }
        catch(Exception exc) {
            System.out.println("Output file is invalid.");
            exc.printStackTrace();
            return;
        }

        try {
            ArrayList<String> dirs = new ArrayList<String>();

            for(String lib : libs) {
                File file = new File(lib);

                if(!file.exists())
                    throw new IllegalArgumentException("Lib does not exist: " + lib);

                try {
                    JarFile jar = new JarFile(file);
                    for(Enumeration<JarEntry> e = jar.entries(); e.hasMoreElements();) {
                        JarEntry entry = e.nextElement();

                        if(dirs.contains(entry.getName()))
                            continue;
                        else
                            dirs.add(entry.getName());

                        if(entry.getName().toLowerCase().startsWith("meta-inf"))
                            continue;

                        InputStream in = jar.getInputStream(entry);

                        jarOS.putNextEntry(new JarEntry(entry.getName()));

                        byte[] data = new byte[1024];
                        int len;
                        while((len = in.read(data)) != -1)
                            jarOS.write(data,0,len);

                        in.close();
                        jarOS.closeEntry();
                    }
                    jar.close();
                }
                catch(IOException exc) {
                    throw new IllegalArgumentException("Problem with lib: " + lib,exc);
                }
            }

            for(String n : natives) {
                File file = new File(n);

                if(!file.exists())
                    throw new IllegalArgumentException("Native does not exist: " + n);

                FileInputStream fis = new FileInputStream(file);

                jarOS.putNextEntry(new JarEntry(getFileName(n)));

                byte[] data = new byte[1024];
                int len;
                while((len = fis.read(data)) != -1)
                    jarOS.write(data, 0, len);

                fis.close();
                jarOS.closeEntry();
            }

            InputStream in = FatJar.class.getResourceAsStream("FatJarLauncher.class");
            jarOS.putNextEntry(new JarEntry("com/ra4king/fatjar/FatJarLauncher.class"));

            byte[] data = new byte[1024];
            int len;
            while((len = in.read(data)) != -1)
                jarOS.write(data,0,len);

            in.close();
            jarOS.closeEntry();

            jarOS.close();
        }
        catch(Exception exc) {
            if(exc.getCause() == null)
                System.err.println(exc.getMessage());
            else
                exc.printStackTrace();

            try {
                jarOS.close();
            }
            catch(Exception exc2) {}

            outputFile.delete();
        }
    }

    private static void printUsage() {
        System.err.println("Usage: -libs [libs] -natives [natives] -main [main class] -output [path]");
        System.err.println("Both [libs] and [natives] can be a semi-colon-separated list of files, relative or absolute");
        System.err.println("The [main class] is in this format: com.example.MainExample");
        System.err.println("The output [path] is the path, relative or absolute, of the final Fat Jar");
    }

    private static String getFileName(String path) {
        path = path.replace('\\', '/');
        return path.substring(path.indexOf('/') + 1);
    }
}