1. 爬虫框架webmagic

WebMagic是一个简单灵活的爬虫框架。基于WebMagic，你可以快速开发出一个高效、易维护的爬虫。

1.1 官网地址

官网文档写的比较清楚，建议大家直接阅读官方文档，也可以阅读下面的内容。地址如下：

官网：http://webmagic.io

中文文档地址: http://webmagic.io/docs/zh/

English: http://webmagic.io/docs/en

2. webmagic与spring boot框架集成

spring boot与webmagic的结合主要有三个模块，分别为爬取模块Processor,入库模块Pipeline，向数据库存入爬取数据，和定时任务模块Scheduled,复制定时爬取网站数据。

2.1 maven添加

<dependency> 
    <groupId>us.codecraft</groupId>
    <artifactId>webmagic-core</artifactId>
    <version>0.5.3</version>
</dependency>
<dependency>
    <groupId>us.codecraft</groupId>
    <artifactId>webmagic-extension</artifactId>
    <version>0.5.3</version>
</dependency>

2.2 爬取模块Processor

爬取简书首页Processor，分析简书首页的页面数据，获取响应的简书链接和标题，放入wegmagic的Page中，到入库模块取出添加到数据库。代码如下：

package com.shang.spray.common.processor;

import com.shang.spray.entity.News;
import com.shang.spray.entity.Sources;
import com.shang.spray.pipeline.NewsPipeline;
import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Spider;
import us.codecraft.webmagic.processor.PageProcessor;
import us.codecraft.webmagic.selector.Selectable;

import java.util.List;

/**
 * info:简书首页爬虫
 * Created by shang on 16/9/9.
 */
public class JianShuProcessor implements PageProcessor {

    private Site site = Site.me()
            .setDomain("jianshu.com")
            .setSleepTime(100)
            .setUserAgent("Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36");
    ;

    public static final String list = "http://www.jianshu.com";

    @Override
    public void process(Page page) {
        if (page.getUrl().regex(list).match()) {
            List<Selectable> list=page.getHtml().xpath("//ul[@class=‘article-list thumbnails‘]/li").nodes();
            for (Selectable s : list) {
                String title=s.xpath("//div/h4/a/text()").toString();
                String link=s.xpath("//div/h4").links().toString();
                News news=new News();
                news.setTitle(title);
                news.setInfo(title);
                news.setLink(link);
                news.setSources(new Sources(5));
                page.putField("news"+title, news);
            }
        }
    }

    @Override
    public Site getSite() {
        return site;
    }

    public static void main(String[] args) {
        Spider spider=Spider.create(new JianShuProcessor());
        spider.addUrl("http://www.jianshu.com");
        spider.addPipeline(new NewsPipeline());
        spider.thread(5);
        spider.setExitWhenComplete(true);
        spider.start();
    }
}

2.3 入库模块Pipeline

入库模块结合spring boot的Repository模块一起组合成入库方法，继承webmagic的Pipeline，然后实现方法，在process方法中获取爬虫模块的数据，然后调用spring boot的save方法。代码如下：

package com.shang.spray.pipeline;

import com.shang.spray.entity.News;
import com.shang.spray.entity.Sources;
import com.shang.spray.repository.NewsRepository;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Repository;
import us.codecraft.webmagic.ResultItems;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.pipeline.Pipeline;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;

/**
 * info:新闻
 * Created by shang on 16/8/22.
 */
@Repository
public class NewsPipeline implements Pipeline {

    @Autowired
    protected NewsRepository newsRepository;

    @Override
    public void process(ResultItems resultItems, Task task) {
        for (Map.Entry<String, Object> entry : resultItems.getAll().entrySet()) {
            if (entry.getKey().contains("news")) {
                News news=(News) entry.getValue();
                Specification<News> specification=new Specification<News>() {
                    @Override
                    public Predicate toPredicate(Root<News> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                        return criteriaBuilder.and(criteriaBuilder.equal(root.get("link"),news.getLink()));
                    }
                };
                if (newsRepository.findOne(specification) == null) {//检查链接是否已存在
                    news.setAuthor("水花");
                    news.setTypeId(1);
                    news.setSort(1);
                    news.setStatus(1);
                    news.setExplicitLink(true);
                    news.setCreateDate(new Date());
                    news.setModifyDate(new Date());
                    newsRepository.save(news);
                }
            }

        }
    }
}

2.4 定时任务模块Scheduled

使用spring boot自带的定时任务注解@Scheduled(cron = "0 0 0/2 * * ? "),每天从0天开始，每两个小时执行一次爬取任务，在定时任务里调取webmagic的爬取模块Processor。代码如下：

package com.shang.spray.common.scheduled;

import com.shang.spray.common.processor.DevelopersProcessor;
import com.shang.spray.common.processor.JianShuProcessor;
import com.shang.spray.common.processor.ZhiHuProcessor;
import com.shang.spray.entity.Config;
import com.shang.spray.pipeline.NewsPipeline;
import com.shang.spray.service.ConfigService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import us.codecraft.webmagic.Spider;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;


/**
 * info:新闻定时任务
 * Created by shang on 16/8/22.
 */
@Component
public class NewsScheduled {
    @Autowired
    private NewsPipeline newsPipeline;

    /**
     * 简书
     */
    @Scheduled(cron = "0 0 0/2 * * ? ")//从0点开始,每2个小时执行一次
    public void jianShuScheduled() {
        System.out.println("----开始执行简书定时任务");
        Spider spider = Spider.create(new JianShuProcessor());
        spider.addUrl("http://www.jianshu.com");
        spider.addPipeline(newsPipeline);
        spider.thread(5);
        spider.setExitWhenComplete(true);
        spider.start();
        spider.stop();
    }

}

2.5 spring boot启用定时任务

在spring boot的Application里启用定时任务注解，@EnableScheduling。代码如下：

package com.shang.spray;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.web.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableScheduling;

/**
 * info:
 * Created by shang on 16/7/8.
 */
@Configuration
@EnableAutoConfiguration
@ComponentScan
@SpringBootApplication
@EnableScheduling
public class SprayApplication extends SpringBootServletInitializer{

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SprayApplication.class);
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SprayApplication.class, args);
    }
}

3. 结束语

使用webmagic是我在水花一现项目中爬取网站数据时使用的的爬虫框架，在综合比较的其他几个爬虫框架后，选择了这个框架，这个框架比较简单易学，且功能强大，我这里只使用了基本的功能，还有许多强大的功能都没有使用。有兴趣的可以去看看官方文档！