IOUtils

public static void copy(File source, File target) throws IOException
    {
        if (source.isDirectory())
        {
            if (!target.exists())
                target.mkdir();

            String[] children = source.list();
            for (int i = 0; i < children.length; i++)
                copy(new File(source, children[i]), new File(target, children[i]));
        }
        else
        {
            InputStream in = new FileInputStream(source);
            OutputStream out = new FileOutputStream(target);

            byte[] buf = new byte[1024];
            int len;
            while ((len = in.read(buf)) > 0)
                out.write(buf, 0, len);

            in.close();
            out.close();
        }
    }