Web爬虫里的问题

Question

public static ArrayList<String>getSubURLs(String urlString){ArrayList<String>list = new ArrayList<>();try{java.net.URL url =new java.net.URL(urlString);Scanner input =new Scanner(url.openStream());int current = 0;while(input.hasNext()){  String line = input.nextLine();current =line.indexOf("http",current);while(current>0){  int endIndex= line.indexOf("\",current);if(endIndex > 0){    list.add(line.substring(current,endIndex));    current = line.indexOf("http:",endIndex);}   else          current = -1;}}}}求大神指教每一行的意思，注意是每一行，采纳必有谢谢！