数据分析案例——51job爬虫

介绍一个java爬虫的案例，使用jsoup进行HTML解析，进而获得数据。

简介

爬虫为获取数据的一种方式，目前流行Python爬虫，Python具有许多支持爬虫的框架。本文中使用java做一个简单的爬虫。

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需求

爬取51job网站的信息数据，爬取大数据相关岗位，主要爬取公司名称，职位名称，地区，薪资情况，发布日期。

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工具jsoup

jsoup 是一款Java 的HTML解析器，可直接解析某个URL地址、HTML文本内容。它提供了一套非常省力的API，可通过DOM，CSS以及类似于jQuery的操作方法来取出和操作数据。

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pom.xml导入依赖

<dependency>
	<groupId>org.jsoupgroupId>
	<artifactId>jsoupartifactId>
	<version>1.11.3version>
dependency>

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代码实现

JobBean.java

public class JobBean {
	private String jobName;
	private String companyName;
	private String addr;
	private String salary;
	private String date;

	public void set(String jobName, String companyName, String addr, String salary, String date) {
		this.jobName = jobName;
		this.companyName = companyName;
		this.addr = addr;
		this.salary = salary;
		this.date = date;
	}

	@Override
	public String toString() {
		return "JobBean [jobName=" + jobName + ", companyName=" + companyName + ", addr=" + addr + ", salary=" + salary
				+ ", date=" + date + "]";
	}

	public String getJobName() {
		return jobName;
	}

	public void setJobName(String jobName) {
		this.jobName = jobName;
	}

	public String getCompanyName() {
		return companyName;
	}

	public void setCompanyName(String companyName) {
		this.companyName = companyName;
	}

	public String getAddr() {
		return addr;
	}

	public void setAddr(String addr) {
		this.addr = addr;
	}

	public String getSalary() {
		return salary;
	}

	public void setSalary(String salary) {
		this.salary = salary;
	}

	public String getDate() {
		return date;
	}

	public void setDate(String date) {
		this.date = date;
	}
}

PageBean.java

import org.jsoup.nodes.Document;

/**
 * 封装页面信息
 * @author Administrator
 *
 */
public class PageBean {
private Document dom;
private String url;
private boolean hasNextPage;
public Document getDom() {
	return dom;
}
public void setDom(Document dom) {
	this.dom = dom;
}
public String getUrl() {
	return url;
}
public void setUrl(String url) {
	this.url = url;
}
public boolean isHasNextPage() {
	return hasNextPage;
}
public void setHasNextPage(boolean hasNextPage) {
	this.hasNextPage = hasNextPage;
}
@Override
public String toString() {
	return "PageBean [dom=" + dom + ", url=" + url + ", hasNextPage=" + hasNextPage + "]";
}
public PageBean(Document dom, String url, boolean hasNextPage) {
	super();
	this.dom = dom;
	this.url = url;
	this.hasNextPage = hasNextPage;
}
public PageBean() {
	super();
}

}

TestJsoup

public class TestJsoup {
	/**
	 * 得到element之后，获取指定的值
	 * 1.标签对的值
	 * 2.属性值
	 * @param args
	 */
	public static void main(String[] args) {
		Document document = getDom();

		Elements select = document.select("#languagelist li a");
		for (Element element : select) {
			//得到每一个元素element
			//标签对的值
			String text = element.text();
			System.out.println(text);
			
			//获取属性值
			String attr = element.attr("href");
			System.out.println(attr);
		}
	}

	/**
	 * 查找标签 1.id 2.class 3.tag（标签） select css选择形式
	 */
	private void getElement() {
		Document document = getDom();
		// 通过id查找 （唯一的）
		Element elementById = document.getElementById("languagelist");
		Elements elementsByTag2 = elementById.getElementsByTag("li");
		

		Elements elementsByTag = document.getElementsByTag("div");
		
		// 通过class查找数据
		Elements elementsByClass = document.getElementsByClass("e");
		
		// 通过css选择器 id class tag 联合形式 （空格）
		Elements select = document.select("#languagelist li a");
		
	}

	/**
	 * 得到网站的所有数据
	 * 
	 * @return
	 */
	private static Document getDom() {
		URL url;
		try {
			url = new URL(
					"https://search.51job.com/list/010000,000000,0000,00,9,99,%25E5%25A4%25A7%25E6%2595%25B0%25E6%258D%25AE,2,1.html?lang=c&stype=&postchannel=0000&workyear=99&cotype=99°reefrom=99&jobterm=99&companysize=99&providesalary=99&lonlat=0%2C0&radius=-1&ord_field=0&confirmdate=9&fromType=&dibiaoid=0&address=&line=&specialarea=00&from=&welfare=");
			Document dom = Jsoup.parse(url, 4000);
			//System.out.println(dom);
			return dom;
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}
}

主程序

public class TestMain {
	public static void main(String[] args) {
		String url = "https://search.51job.com/list/010000,000000,0000,00,9,99,%25E5%25A4%25A7%25E6%2595%25B0%25E6%258D%25AE,2,1.html?lang=c&stype=&postchannel=0000&workyear=99&cotype=99°reefrom=99&jobterm=99&companysize=99&providesalary=99&lonlat=0%2C0&radius=-1&ord_field=0&confirmdate=9&fromType=&dibiaoid=0&address=&line=&specialarea=00&from=&welfare=";
		Document document = getDocument(url);
		PageBean page = new PageBean();
		page.setDom(document);

		while (true) {
			List<JobBean> job = getJob(page);
			for (JobBean jobBean : job) {
				System.out.println(jobBean);
			}
			getNextPage(page);
			if (page.isHasNextPage()) {
				Document document2 = getDocument(page.getUrl());
				page.setDom(document2);
			} else {
				break;
			}
			try {
				Thread.sleep(1000);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * 获取/判断是否有下一页
	 */
	private static void getNextPage(PageBean page) {
		Document dom = page.getDom();
		Element select = dom.select(".bk").get(1);
		Elements select2 = select.select("a");
		if (select2 != null && select2.size() > 0) {
			String url = select2.get(0).attr("href");
			page.setUrl(url);
			page.setHasNextPage(true);
		} else {
			page.setHasNextPage(false);
		}
	}

	/**
	 * 通过document获取具体的岗位数据
	 */
	private static List<JobBean> getJob(PageBean page) {
		List<JobBean> list = new ArrayList<>();
		Document dom = page.getDom();
		Elements select = dom.select("#resultList .el");
		select.remove(0);
		for (Element element : select) {
			Elements select1 = element.select(".t1 a");
			String jobName = select1.text();
			Elements select2 = element.select(".t2 a");
			String companyName = select2.attr("title");
			String addr = element.select(".t3").text();
			String salary = element.select(".t4").text();
			String date = element.select(".t5").text();
			JobBean jobBean = new JobBean();
			jobBean.set(jobName, companyName, addr, salary, date);
			list.add(jobBean);
		}
		return list;
	}

	/**
	 * 获取document
	 * 
	 * @param url
	 * @return
	 */
	private static Document getDocument(String url) {
		try {
			Document document = Jsoup.parse(new URL(url), 4000);
			return document;
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;

	}
}

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运行结果概览