class URL implements Serializable {

    public static URL valueOf(String url) {
        if (url == null || (url = url.trim()).length() == 0) {
            throw new IllegalArgumentException("url == null");
        }
        String protocol = null;
        String username = null;
        String password = null;
        String host = null;
        int port = 0;
        String path = null;
        Map<String, String> parameters = null;
        int i = url.indexOf("?"); // seperator between body and parameters 
        if (i >= 0) {
            String[] parts = url.substring(i + 1).split("\\&");
            parameters = new HashMap<String, String>();
            for (String part : parts) {
                part = part.trim();
                if (part.length() > 0) {
                    int j = part.indexOf('=');
                    if (j >= 0) {
                        parameters.put(part.substring(0, j), part.substring(j + 1));
                    } else {
                        parameters.put(part, part);
                    }
                }
            }
            url = url.substring(0, i);
        }
        i = url.indexOf("://");
        if (i >= 0) {
            if (i == 0) throw new IllegalStateException("url missing protocol: \"" + url + "\"");
            protocol = url.substring(0, i);
            url = url.substring(i + 3);
        } else {
            // case: file:/path/to/file.txt
            i = url.indexOf(":/");
            if (i >= 0) {
                if (i == 0) throw new IllegalStateException("url missing protocol: \"" + url + "\"");
                protocol = url.substring(0, i);
                url = url.substring(i + 1);
            }
        }

        i = url.indexOf("/");
        if (i >= 0) {
            path = url.substring(i + 1);
            url = url.substring(0, i);
        }
        i = url.lastIndexOf("@");
        if (i >= 0) {
            username = url.substring(0, i);
            int j = username.indexOf(":");
            if (j >= 0) {
                password = username.substring(j + 1);
                username = username.substring(0, j);
            }
            url = url.substring(i + 1);
        }
        i = url.indexOf(":");
        if (i >= 0 && i < url.length() - 1) {
            port = Integer.parseInt(url.substring(i + 1));
            url = url.substring(0, i);
        }
        if (url.length() > 0) host = url;
        return new URL(protocol, username, password, host, port, path, parameters);
    }

    protected  URL();
    public  URL(String protocol, String host, int port);
    public  URL(String protocol, String host, int port, String[] pairs);
    public  URL(String protocol, String host, int port, Map<String, String> parameters);
    public  URL(String protocol, String host, int port, String path);
    public  URL(String protocol, String host, int port, String path, String... pairs);
    public  URL(String protocol, String host, int port, String path, Map<String, String> parameters);
    public  URL(String protocol, String username, String password, String host, int port, String path);
    public  URL(String protocol, String username, String password, String host, int port, String path, String... pairs);
    public  URL(String protocol, String username, String password, String host, int port, String path, Map<String, String> parameters);

}