Here you can find the source of isURL(String url)
public static boolean isURL(String url)
//package com.java2s; //License from project: Apache License import java.util.regex.Pattern; public class Main { public static boolean isURL(String url) { Pattern pattern = Pattern.compile( "^(https?|ftp):\\/\\/(((([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-f]{2})|[!\\$&'\\(\\)\\*\\+,;=]|:)*@)?(((\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5]))|((([a-z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(([a-z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])*([a-z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])))\\.)+(([a-z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(([a-z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])*([a-z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])))\\.?)(:\\d*)?)(\\/((([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-f]{2})|[!\\$&'\\(\\)\\*\\+,;=]|:|@)+(\\/(([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-f]{2})|[!\\$&'\\(\\)\\*\\+,;=]|:|@)*)*)?)?(\\?((([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-f]{2})|[!\\$&'\\(\\)\\*\\+,;=]|:|@)|[\\uE000-\\uF8FF]|\\/|\\?)*)?(\\#((([a-z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-f]{2})|[!\\$&'\\(\\)\\*\\+,;=]|:|@)|\\/|\\?)*)?$"); return pattern.matcher(url).matches(); }/* w w w. j a v a 2 s . co m*/ }