Here you can find the source of isAbsoluteURL(String url)
public static boolean isAbsoluteURL(String url)
//package com.java2s; //License from project: LGPL public class Main { public static boolean isAbsoluteURL(String url) { String urlLC = url.toLowerCase().trim(); return urlLC.startsWith("http://") || urlLC.startsWith("https://") || urlLC.startsWith("ftp://") || urlLC.startsWith("file://") || urlLC.startsWith("//"); }// ww w . j av a2s. c o m }