正文
JAVA爬虫实践（实践四：webMagic和phantomjs和淘宝爬虫）
提示：扫一扫查出行【扫一扫了解最新限行尾号】
复制提示
webMagic虽然方便，但是也有它不适用的地方，比如定向的某个单页面爬虫，或者存在大量ajax请求，页面的跳转请求全都混淆在js里。
这时可以用webMagic结合phantomjs来真实模拟页面请求，即不仅仅获取数据，而是将整个页面完整渲染出来。虽然这样会使爬虫速度变慢很多，但是不失为一种快捷方便的解决方法。
PhantomJS 是一个基于 WebKit 的服务器端JavaScript API。它全面支持web而不需浏览器支持，其快速，原生支持各种Web标准： DOM 处理, CSS 选择器, JSON, Canvas, 和 SVG。 PhantomJS 可以用于页面自动化 ， 网络监测， 网页截屏，以及 无界面测试 等。
淘宝就是这种难以用普通爬虫方法爬取的网站。直接发送GET请求到淘宝基本获取不到什么有效的内容和链接。
还好webMagic虽然默认使用httpClient获取网页，但是它也将它获取网页的方法Downloader开放出来。这样可以在Downloader里使用phantomjs获取页面。
phantomjs使用方法
1.下载安装phantomjs
2.编写js脚本
system = require('system') //传递一些需要的参数给js文件
address = system.args[1];//获得命令行第二个参数 ，也就是指定要加载的页面地址，接下来会用到
var page = require('webpage').create();
var url = address;
page.open(url, function (status) {
if (status !== 'success') {
console.log('Unable to post!');
} else {
var encodings = ["euc-jp", "sjis", "utf8", "System"];//这一步是用来测试输出的编码格式，选择合适的编码格式很重要，不然你抓取下来的页面会乱码o(╯□╰)o，给出的几个编码格式是官网上的例子，根据具体需要自己去调整。
for (var i = 3; i < encodings.length; i++) {//我这里只要一种编码就OK啦
phantom.outputEncoding = encodings[i];
console.log(phantom.outputEncoding+page.content);//最后返回webkit加载之后的页面内容
}
}
phantom.exit();
});
3.测试
package util; import java.io.BufferedReader;
import java.io.File;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter; import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.selector.PlainText; public class GetAjaxHtml {
public static String getAjaxContent(String url) throws Exception {
Runtime rt = Runtime.getRuntime();
Process p = rt
.exec("D:/phantomjs-2.1.1-windows/bin/phantomjs.exe D:/s.js "
+ url);
InputStream is = p.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
StringBuffer sbf = new StringBuffer();
String tmp = "";
while ((tmp = br.readLine()) != null) {
sbf.append(tmp + "\n");
}
return sbf.toString();
} public static Page download(Request request) {
Page page = new Page();
try {
String url = request.getUrl();
String html = getAjaxContent(url);
page.setRawText(html);
page.setUrl(new PlainText(url));
page.setRequest(request);
return page;
} catch (Exception e) {
System.out.println("download出错了!");
return page;
}
} public static void main(String[] args) throws Exception {
long start = System.currentTimeMillis();
String result = getAjaxContent("http://www.taobao.com");
System.out.println(result);
// 创建新文件
String path = "D:\\testFile\\taobao.html";
PrintWriter printWriter = null;
printWriter = new PrintWriter(new FileWriter(new File(path)));
printWriter.write(result);
printWriter.close();
long end = System.currentTimeMillis();
System.out.println("===============耗时：" + (end - start)
+ "===============");
}
}
webMagic结合phantomjs淘宝爬虫
package taobao; import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Spider;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.downloader.Downloader;
import us.codecraft.webmagic.processor.PageProcessor;
import util.GetAjaxHtml;
import util.UuidUtil;
import csdnblog.dao.TaobaoDao;
import csdnblog.model.Taobao; public class TaobaoPageProcessor implements PageProcessor { private TaobaoDao taobaoDao = new TaobaoDao(); // 抓取网站的相关配置，包括：编码、抓取间隔、重试次数等
private Site site = Site.me().setRetryTimes(3).setSleepTime(1000); @Override
public Site getSite() {
return site;
} @Override
public void process(Page page) {
page.addTargetRequests(page.getHtml().links()
.regex(".*item\\.taobao\\.com/item\\.htm\\?id=.*")
.all());
page.addTargetRequests(page.getHtml().links()
.regex("https://s\\.taobao\\.com/list.*")
.all()); //如果是详情页
if(page.getUrl().regex("https://item\\.taobao\\.com/item\\.htm\\?id=.*").match()) { Taobao taobao = new Taobao();
taobao.setId(UuidUtil.getId());
taobao.setUrl(page.getUrl().toString());
taobao.setMaintitle(page.getHtml().xpath("//h3[@class='tb-main-title']/text()").get());
taobao.setSubtitle(page.getHtml().xpath("//p[@class='tb-subtitle']/text()").get());
taobao.setPrice(page.getHtml().xpath("//strong[@id='J_StrPrice']/em[@class='tb-rmb-num']/text()").get());
taobao.setTaobaoprice(page.getHtml().xpath("//em[@id='J_PromoPriceNum']/text()").get());
taobao.setRatecounter(page.getHtml().xpath("//strong[@id='J_RateCounter']/text()").get());
taobao.setSellcounter(page.getHtml().xpath("//strong[@id='J_SellCounter']/text()").get());
// 把对象存入数据库
taobaoDao.addTaobao(taobao);
// 把对象输出控制台
System.out.println(taobao.toString());
}
} public static void main(String[] args) {
Spider.create(new TaobaoPageProcessor()).setDownloader(new Downloader() { @Override
public void setThread(int threadNum) {
} @Override
public Page download(Request request, Task task) {
return GetAjaxHtml.download(request);
}
}).addUrl("https://s.taobao.com/list?q=%E5%A4%B9%E5%85%8B&cat=50344007&style=grid&seller_type=taobao").thread(5).run();
}
}
Model
package csdnblog.model;
public class Taobao {
private String id;
private String maintitle;
private String subtitle;
// url
private String url;
// 价格
private String price;
// 淘宝价
private String taobaoprice;
// 累计评价
private String ratecounter;
// 交易成功
private String sellcounter;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getMaintitle() {
return maintitle;
}
public void setMaintitle(String maintitle) {
this.maintitle = maintitle;
}
public String getSubtitle() {
return subtitle;
}
public void setSubtitle(String subtitle) {
this.subtitle = subtitle;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getTaobaoprice() {
return taobaoprice;
}
public void setTaobaoprice(String taobaoprice) {
this.taobaoprice = taobaoprice;
}
public String getRatecounter() {
return ratecounter;
}
public void setRatecounter(String ratecounter) {
this.ratecounter = ratecounter;
}
public String getSellcounter() {
return sellcounter;
}
public void setSellcounter(String sellcounter) {
this.sellcounter = sellcounter;
}
public Taobao(String id, String maintitle, String subtitle, String url,
String price, String taobaoprice, String ratecounter,
String sellcounter) {
super();
this.id = id;
this.maintitle = maintitle;
this.subtitle = subtitle;
this.url = url;
this.price = price;
this.taobaoprice = taobaoprice;
this.ratecounter = ratecounter;
this.sellcounter = sellcounter;
}
public Taobao() {
super();
}
@Override
public String toString() {
return "Taobao [id=" + id + ", maintitle=" + maintitle + ", subtitle="
+ subtitle + ", url=" + url + ", price=" + price
+ ", taobaoprice=" + taobaoprice + ", ratecounter="
+ ratecounter + ", sellcounter=" + sellcounter + "]";
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
}
