public static String expand(String value) throws ExpandException 
{
        return expand(value, false);
}

 public static String expand(String value,
    boolean encodeURL) throws ExpandException 
{
        if (value == null)
            return null;
        int p = value.indexOf("${", 0);
        // no special characters
        if (p == -1) return value;
        StringBuffer sb = new StringBuffer(value.length());
        int max = value.length();
        int i = 0;  // index of last character we copied
    scanner:
        while (p <  max) {
            if (p  > i) {
                // copy in anything before the special stuff
                sb.append(value.substring(i, p));
                i = p;
            }
            int pe = p+2;
            // do not expand ${{ ... }}
            if (pe <  max && value.charAt(pe) == '{') {
                pe = value.indexOf("}}", pe);
                if (pe == -1 || pe+2 == max) {
                    // append remaining chars
                    sb.append(value.substring(p));
                    break scanner;
                } else {
                    // append as normal text
                    pe++;
                    sb.append(value.substring(p, pe+1));
                }
            } else {
                while ((pe <  max) && (value.charAt(pe) != '}')) {
                    pe++;
                }
                if (pe == max) {
                    // no matching '}' found, just add in as normal text
                    sb.append(value.substring(p, pe));
                    break scanner;
                }
                String prop = value.substring(p+2, pe);
                if (prop.equals("/")) {
                    sb.append(java.io.File.separatorChar);
                } else {
                    String val = System.getProperty(prop);
                    if (val != null) {
                        if (encodeURL) {
                            // encode 'val' unless it's an absolute URI
                            // at the beginning of the string buffer
                            try {
                                if (sb.length()  > 0 ||
                                    !(new URI(val)).isAbsolute()) {
                                    val = sun.net.www.ParseUtil.encodePath(val);
                                }
                            } catch (URISyntaxException use) {
                                val = sun.net.www.ParseUtil.encodePath(val);
                            }
                        }
                        sb.append(val);
                    } else {
                        throw new ExpandException(
                                             "unable to expand property " +
                                             prop);
                    }
                }
            }
            i = pe+1;
            p = value.indexOf("${", i);
            if (p == -1) {
                // no more to expand. copy in any extra
                if (i <  max) {
                    sb.append(value.substring(i, max));
                }
                // break out of loop
                break scanner;
            }
        }
        return sb.toString();
}