需求分析:

首先访问京东，搜索手机，分析页面，我们抓取以下商品数据：
商品图片、价格、标题、商品详情页

一.开发准备

技术要求:springboot   spring data jpa   httpclient  jsoup

数据库准备:

use crawler;

CREATE TABLE `jd_item` (
  `id` bigint(10) NOT NULL AUTO_INCREMENT COMMENT '主键 id',
  `spu` bigint(15) DEFAULT NULL COMMENT '商品集合 id',
  `sku` bigint(15) DEFAULT NULL COMMENT '商品最小品类单元 id',
  `title` varchar(100) DEFAULT NULL COMMENT '商品标题',
  `price` bigint(10) DEFAULT NULL COMMENT '商品价格',
  `pic` varchar(200) DEFAULT NULL COMMENT '商品图片',
  `url` varchar(200) DEFAULT NULL COMMENT '商品详情地址',
  `created` datetime DEFAULT NULL COMMENT '创建时间',
  `updated` datetime DEFAULT NULL COMMENT '更新时间',
  PRIMARY KEY (`id`),
  KEY `sku` (`sku`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COMMENT='京东商品表'

1.创建springboot 工程  ,导入依赖

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <groupId>com.itheima</groupId>
    <artifactId>crawler</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- HttpClient -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.3</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!-- 日志 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.25</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

        <!--Jsoup-->
        <dependency>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
            <version>1.10.3</version>
        </dependency>


        <!--工具-->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.7</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

    </dependencies>

2.编写配置文件

3.编写启动类

@SpringBootApplication
public class SpringBootRun {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootRun.class,args);
    }
}

4.编写持久化类

@Entity
@Table(name = "jd_item")
public class Item {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String spu;
    private String sku;
    private String title;
    private Long price;
    private String pic;
    private String url;
    private Date created;
    private Date updated;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getSpu() {
        return spu;
    }

    public void setSpu(String spu) {
        this.spu = spu;
    }

    public String getSku() {
        return sku;
    }

    public void setSku(String sku) {
        this.sku = sku;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Long getPrice() {
        return price;
    }

    public void setPrice(Long price) {
        this.price = price;
    }

    public String getPic() {
        return pic;
    }

    public void setPic(String pic) {
        this.pic = pic;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public Date getCreated() {
        return created;
    }

    public void setCreated(Date created) {
        this.created = created;
    }

    public Date getUpdated() {
        return updated;
    }

    public void setUpdated(Date updated) {
        this.updated = updated;
    }

}

5.编写dao接口

public interface ItemDao extends JpaRepository<Item,Long>{

}

6.编写service接口以及实现列

@Service
@Transactional
public class ItemServiceImpl implements ItemService {

    @Autowired
    private ItemDao itemDao;
    @Override
    public void save(Item item) {
        itemDao.save(item);

    }
    //条件查询
    @Override
    public List<Item> findAll(Item item) {
        Example example = Example.of(item);
        List<Item> all = this.itemDao.findAll(example);
        return all;
    }
}

二.代码实现

封装HttpClient

package com.itheima.utils;

import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;
import org.springframework.context.annotation.ComponentScan;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.UUID;

@ComponentScan
public class HttpUtil {
    //http连接池
    private static PoolingHttpClientConnectionManager pool;
    static{
        pool = new PoolingHttpClientConnectionManager();
        pool.setMaxTotal(100);
        pool.setDefaultMaxPerRoute(50);
    }

    /**
     * 获取页面源码
     */
    public String getHtml(String url){
        CloseableHttpClient build = HttpClients.custom().setConnectionManager(pool).build();
        //通过get请求
        HttpGet httpGet = new HttpGet();
        httpGet.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.81 Safari/537.36");
        httpGet.setConfig(this.getConfig());
        //发送请求
        try {
            CloseableHttpResponse response = build.execute(httpGet);
            //判断发送的返回的状态
            if (response.getStatusLine().getStatusCode()==200){
                String string = EntityUtils.toString(response.getEntity(), "UTF-8");
                return string;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return null;
    }
    /**
     * 下载图片
     */
    public String getImage(String imgUrl){
        CloseableHttpClient build = HttpClients.custom().setConnectionManager(pool).build();
        HttpGet httpGet = new HttpGet();
        httpGet.setConfig(this.getConfig());
        try {
            CloseableHttpResponse response = build.execute(httpGet);
            if (response.getStatusLine().getStatusCode()==200){
               //后缀名 .jpg  .png
                String suffix = imgUrl.substring(imgUrl.lastIndexOf("."));
                String newImg = UUID.randomUUID()+suffix;

                //保存图片
                FileOutputStream fileOutputStream = new FileOutputStream(new File("F:\\img\\" + newImg));
                response.getEntity().writeTo(fileOutputStream);
                return newImg;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }

        return null;
    }
    private RequestConfig getConfig(){
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectionRequestTimeout(500)
                .setConnectTimeout(500)
                .setSocketTimeout(1000 * 10)
                .build();
        return requestConfig;
    }
}

使用定时任务编写页面抓取代码

package com.itheima.utils;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.itheima.po.Item;
import com.itheima.service.ItemService;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import java.io.IOException;
import java.util.Date;

@Component
public class ItemTask {

    @Autowired
    private ItemService itemService;

    @Autowired
    private HttpUtil httpUtil;

    public static final ObjectMapper MAPPER = new ObjectMapper();

    //设置定时任务,间隔100秒执行一次
    @Scheduled(fixedDelay = 1000 * 50)
    public void process(){

        //京东的url 地址
        String url = "https://search.jd.com/Search?keyword=%E6%89%8B%E6%9C%BA&enc=utf-8&qrst=1&rt=1&stop=1&vt=2&wq=%E6%89%8B%E6%9C%BA&cid2=653&cid3=655&s=59&click=0&page=";
        for (int i = 1; i < 10; i=i+2) {
            String html = this.httpUtil.getHtml(url+i);
            //解析页面数据保存到数据库
            this.parseHtml(html);
        }
        System.out.println("执行完成");
    }
    //解析页面数据库保存到数据库
    private void parseHtml(String html) {
        //通过Jsoup解析文件
        Document document = Jsoup.parse(html);
        //获取spu 的dom 数据
        Elements spuelements = document.select("div#J_goodsList li.gl-item");
        for (Element spuelement : spuelements) {
            String spuId = spuelement.attr("data-spu");
            Elements skuelements = spuelement.select("div.p-scroll li.ps-item");
            for (Element skuelement : skuelements) {
                Item item = new Item();
                item.setSpu(spuId);
                //获得skuid
                String skuid = skuelement.select("img").attr("data-sku");
                item.setSku(skuid);
                //获得图片的url路径
                String skuUrl = "https://item.jd.com/"+skuid+".html";
                item.setUrl(skuUrl);
                //发送请求获得商品详情页的数据
                String skuHtml = httpUtil.getHtml(skuUrl);
                //获得详情页的dom树
                Document skuDocumet = Jsoup.parse(skuHtml);
                String skuTitle = skuDocumet.select("div.sku-name").text();
                item.setTitle(skuTitle);
                //注意:因为价格是异步请求的,所以我们通过ajax获得
                String priceUrl = "https://p.3.cn/prices/mgets?skuIds=J_"+skuid;
                String parceHtml = httpUtil.getHtml(priceUrl);
                ObjectMapper objectMapper = new ObjectMapper();
                try {
                    long price = objectMapper.readTree(priceUrl).get(0).get("p").asLong();
                    item.setPrice(price);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                //获取路径
                String imgUrl = skuelement.select("img").attr("src");
                if (StringUtils.isEmpty(imgUrl)){
                    imgUrl = skuelement.select("img").attr("data-lazy-img");
                }
                imgUrl = imgUrl.replace("/n9/","/n7/");
                String imageNewName= httpUtil.getImg("http:" + imgUrl);
                item.setPic(imageNewName);
                item.setCreated(new Date());
                itemService.save(item);

            }
        }
    }
}

使用json解析获得的页面

package com.itheima.utils;

import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;
import org.springframework.stereotype.Component;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.UUID;

@Component
public class HttpUtil {
    private static PoolingHttpClientConnectionManager pool;

    static{
        pool = new PoolingHttpClientConnectionManager();
        pool.setMaxTotal(200);
        pool.setDefaultMaxPerRoute(50);
    }
    /**
     * 使用httpclient抓取页面
     * @param url
     * @return
     */
    public String getHtml(String url){
        CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(pool).build();
        HttpGet httpGet = new HttpGet(url);
        httpGet.setHeader("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.81 Safari/537.36");
        httpGet.setConfig(this.getConfig());
        try {
            CloseableHttpResponse response = httpClient.execute(httpGet);
            if(response.getStatusLine().getStatusCode() == 200){
                String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                return content;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return null;
    }
    /**
     * 获取图片，并且保存在本地文件
     * 返回图片的新文件名
     * @param imgUrl
     * @return
     */
    public String getImg(String imgUrl){
        CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(pool).build();
        HttpGet httpGet = new HttpGet(imgUrl);
        httpGet.setConfig(this.getConfig());
        try {
            CloseableHttpResponse response = httpClient.execute(httpGet);
            //获取图片后缀 .jpg .png
            String suffix = imgUrl.substring(imgUrl.lastIndexOf("."));
            //创建新文件名
            String imgNewName = UUID.randomUUID()+suffix;
            if(response.getStatusLine().getStatusCode() ==200){
                //通过流保存图片文件
                FileOutputStream outputStream = new FileOutputStream("F:\\img\\"+imgNewName);
                response.getEntity().writeTo(outputStream);
                return imgNewName;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return null;
    }

    /**
     * 生成配置
     * @return
     */
    private RequestConfig getConfig(){
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectionRequestTimeout(1000)
                .setConnectTimeout(1000)
                .setSocketTimeout(1000 * 10)
                .build();
        return requestConfig;
    }
}