判斷一個url是否合法

public class Tools {
    private static String pattern = "^([hH][tT]{2}[pP]://|[hH][tT]{2}[pP][sS]://)(([A-Za-z0-9-~]+).)+([A-Za-z0-9-~\\/])+$";

    /**
     * 判斷 url 是否合法
     */
    public static boolean isUrl(String url) {
        Pattern httpPattern = Pattern.compile(pattern);
        if (httpPattern.matcher(url).matches()) {
            return true;
        }
        return false;
    }
}