为什么抓取不到还报空指针，希望各路大神能帮忙解决下

Question

package com;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

/**

• 网页数据抓取工具类 * */

public class Damo {

/**
 * 获取网页源代码
 * @throws IOException 
 * @throws IOException 
 *
 */

public static String getHtmlResouceByUrl(String url,String encoding) {
    URL urlObj=null;
    URLConnection uc=null;
    InputStreamReader isr=null;
    BufferedReader reader=null;
    StringBuffer buffer=null;
    try {
        //建立网络连接
        urlObj=new URL(url);
        //打开网络连接
        try {
            uc=urlObj.openConnection();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //建立文件输入流
        try {
            isr=new InputStreamReader(uc.getInputStream(),encoding);
        } catch (UnsupportedEncodingException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        //建立缓存写入
        reader = new BufferedReader(isr);
        //临时
        String temp=null;
        try {
            while ((temp=reader.readLine())!=null) {

// buffer.append(temp+"\n");
System.out.println(temp+"\n");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{

        if(isr!=null){
            //关闭流
            try {
                isr.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            }


    }


    return buffer.toString();
}

/*

• 爬取互动值
  */
  public static List> getInFo(String url,String encoding){
  //拿到源代码
  String html = getHtmlResouceByUrl(url, encoding);
  //解析代码文件
  Document document = Jsoup.parse(html);
  //获取代码的具体内容
  Element element = document.getElementById("1");
  //获取结果
  Elements elements = document.getElementsByClass("f_card_lricon");

  List<HashMap<String, String>> maps =new ArrayList<HashMap<String,String>>();    
  
  HashMap<String, String> map =null;
   for (Element el : elements) {
      map = new HashMap<String, String>();
      //获取评论数
      String comment=el.getElementsByClass("comment").text();
  
      //获取标题
      String comment1=el.getElementsByClass("f_card_h4").text();
  
      map.put(comment, "f_card_lricon");
      map.put(comment1,"f_card_h4");
  
      maps.add(map);
  }
  
  return maps;
  

  }

  public static void main(String[] args) {
  // String webString=getHtmlResouceByUrl("http://news.baidu.com/","utf-8");
  // String webString=getHtmlResouceByUrl("http://www.163.com/","gbk");
  // System.out.println(webString);
  String urlString = "http://k.sina.cn/article_1707602817_65c7f381001002v4u.html?kfrome=auto&local=&subch=3&vt=4";
  List> list =getInFo(urlString, "utf-8");
  System.out.println(list);

  }
  }
  

Answer 1

空指针你先判断哈，判断是否为空，不为空执行，为空执行为空的逻辑，这样就不会报错了