JAVA爬虫实践（实践四：webMagic和phantomjs和淘宝爬虫）

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;
    }

}