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！