下面代码，已经实现网页抓取，但是小弟我想用indexOf选取其中的代码

import java.io.*;import java.net.HttpURLConnection;import jxl.*;import java.net.*;import jxl.Cell;import jxl.Sheet;import jxl.Workbook;public class URLUtil {    static int x;    static int y;    static String ip=null;    static String input1=null;    static String input2=null;    public static String getHtml(String urlString){        try{            StringBuffer html= new StringBuffer();            URL url=new URL(urlString);            HttpURLConnection conn=(HttpURLConnection)url.openConnection();            InputStreamReader isr=new InputStreamReader(conn.getInputStream());            BufferedReader br = new BufferedReader(isr);            String temp;                        while((temp = br.readLine())!=null){                html.append(temp).append("\n");            }            br.close();            isr.close();            return html.toString();        }catch (Exception e){            e.printStackTrace();            return null;        }            }            public static void main(String[] args){                 try{            Workbook book=Workbook.getWorkbook(new File("产品分类.map.xls"));            Sheet sheet=book.getSheet(0);            for(int i=1;i<sheet.getRows();i++){                Cell c=sheet.getCell(5,i);        System.out.println(URLUtil.getHtml(sheet.getCell(5,i).getContents()));    }book.close();    }catch(Exception e){                System.out.println(e);    }        }}        

 
  Parser parser = new Parser("http://****"); 
  NodeFilter filter = new AndFilter(new TagNameFilter("a"),new HasParentFilter(new TagNameFilter("li"))) ; 
  
 	NodeList nodes = parser.extractAllNodesThatMatch(filter); 
 	int resultNum = nodes.size(); 
 	if (resulNum > 0) { 
 		for (NodeIterator ni = nodes.elements(); ni.hasMoreNodes();) { 
 			System.out.println(ni.nextNode().toHtml()); 
 		} 
 				}