是的,Java也可以做网络爬虫,不仅可以爬静态网页的图片,也可以爬动态网页的图片,比如采用Ajax技术进行异步加载的百度瀑布流。
以前有写过用Java进行百度图片的抓取,但只能抓取到第一二页,本博文则对此问题进行了深入研究,提出了另外一种思路解决问题。我的思路是这样的:以前人们总认为既然百度瀑布流是采用JavaScript进行异步加载的,那么爬取图片至少要有一个模拟浏览器,比如Java领域中的*面浏览器工具HtmlUnit,但后来我发现其实Jsoup也是可以的,只要用Jsoup去向百度服务器发送Ajax请求就行了,幸运的是我在观察百度图片的ajax请求时还真发现有两个类型的请求方式:avatarjson和acjson,实验告诉我们第一种请求方式已经几乎可以满足我们的所有需求。
本博文所实现的效果是:根据输入的多个关键字,可以按定制的页数把各自关键字的搜索结果下载到本地文件夹中。具体如下所示:
废话不多说,程序满上------->
- package com.kendy.spider;
- import java.io.File;
- import java.io.FileNotFoundException;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.InputStream;
- import java.net.HttpURLConnection;
- import java.net.URL;
- import java.net.URLConnection;
- import java.util.ArrayList;
- import java.util.List;
- import java.util.regex.Matcher;
- import java.util.regex.Pattern;
- import org.apache.commons.lang3.StringEscapeUtils;
- import org.jsoup.Jsoup;
- import org.jsoup.nodes.Document;
- // 爬取百度图片
- public class JsoupBaidu2 {
- public static void main(String[] args) throws Exception{
- String downloadPath = "C:\\Users\\Kendy\\Desktop\\中国明星图";
- List<String> list = nameList("凯莉·布鲁克 詹妮弗·洛佩兹 碧昂斯·诺里斯");
- getPictures(list,1,downloadPath); //1代表下载一页,一页一般有30张图片
- }
- public static void getPictures(List<String> keywordList, int max,String downloadPath) throws Exception{ // key为关键词,max作为爬取的页数
- String gsm=Integer.toHexString(max)+"";
- String finalURL = "";
- String tempPath = "";
- for(String keyword : keywordList){
- tempPath = downloadPath;
- if(!tempPath.endsWith("\\")){
- tempPath = downloadPath+"\\";
- }
- tempPath = tempPath+keyword+"\\";
- File f = new File(tempPath);
- if(!f.exists()){
- f.mkdirs();
- }
- int picCount = 1;
- for(int page=0;page<=max;page++) {
- sop("正在下载第"+page+"页面");
- Document document = null;
- try {
- String url ="http://image.baidu.com/search/avatarjson?tn=resultjsonavatarnew&ie=utf-8&word="+keyword+"&cg=star&pn="+page*30+"&rn=30&itg=0&z=0&fr=&width=&height=&lm=-1&ic=0&s=0&st=-1&gsm="+Integer.toHexString(page*30);
- sop(url);
- document = Jsoup.connect(url).data("query", "Java")//请求参数
- .userAgent("Mozilla/4.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)")//设置urer-agent get();
- .timeout(5000)
- .get();
- String xmlSource = document.toString();
- xmlSource = StringEscapeUtils.unescapeHtml3(xmlSource);
- sop(xmlSource);
- String reg = "objURL\":\"http://.+?\\.jpg";
- Pattern pattern = Pattern.compile(reg);
- Matcher m = pattern.matcher(xmlSource);
- while (m.find()) {
- finalURL = m.group().substring(9);
- sop(keyword+picCount+++":"+finalURL);
- download(finalURL,tempPath);
- sop(" 下载成功");
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
- sop("下载完毕");
- delMultyFile(downloadPath);
- sop("已经删除所有空图");
- }
- public static void delMultyFile(String path){
- File file = new File(path);
- if(!file.exists())
- throw new RuntimeException("File \""+path+"\" NotFound when excute the method of delMultyFile()....");
- File[] fileList = file.listFiles();
- File tempFile=null;
- for(File f : fileList){
- if(f.isDirectory()){
- delMultyFile(f.getAbsolutePath());
- }else{
- if(f.length()==0)
- sop(f.delete()+"---"+f.getName());
- }
- }
- }
- public static List<String> nameList(String nameList){
- List<String> arr = new ArrayList<>();
- String[] list;
- if(nameList.contains(","))
- list= nameList.split(",");
- else if(nameList.contains("、"))
- list= nameList.split("、");
- else if(nameList.contains(" "))
- list= nameList.split(" ");
- else{
- arr.add(nameList);
- return arr;
- }
- for(String s : list){
- arr.add(s);
- }
- return arr;
- }
- public static void sop(Object obj){
- System.out.println(obj);
- }
- //根据图片网络地址下载图片
- public static void download(String url,String path){
- //path = path.substring(0,path.length()-2);
- File file= null;
- File dirFile=null;
- FileOutputStream fos=null;
- HttpURLConnection httpCon = null;
- URLConnection con = null;
- URL urlObj=null;
- InputStream in =null;
- byte[] size = new byte[1024];
- int num=0;
- try {
- String downloadName= url.substring(url.lastIndexOf("/")+1);
- dirFile = new File(path);
- if(!dirFile.exists() && path.length()>0){
- if(dirFile.mkdir()){
- sop("creat document file \""+path.substring(0,path.length()-1)+"\" success...\n");
- }
- }else{
- file = new File(path+downloadName);
- fos = new FileOutputStream(file);
- if(url.startsWith("http")){
- urlObj = new URL(url);
- con = urlObj.openConnection();
- httpCon =(HttpURLConnection) con;
- in = httpCon.getInputStream();
- while((num=in.read(size)) != -1){
- for(int i=0;i<num;i++)
- fos.write(size[i]);
- }
- }
- }
- }catch (FileNotFoundException notFoundE) {
- sop("找不到该网络图片....");
- }catch(NullPointerException nullPointerE){
- sop("找不到该网络图片....");
- }catch(IOException ioE){
- sop("产生IO异常.....");
- }catch (Exception e) {
- e.printStackTrace();
- }finally{
- try {
- fos.close();
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- }
- }