哪位高手有截取url中 一级域名的 java代码

String s = "topic.csdn.net/u/20120604/22/2479ec15-887a-4a7f-9ca6-042d37214302.html";Pattern p = Pattern.compile("(?<=//|)((\\w)+\\.)+\\w+");Matcher m = p.matcher(s);if(m.find()){      System.out.println(m.group());}