colly 自动抓取资讯

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colly 在golang中的地位,比之scrapy在python的作用,都是爬虫界的大佬。本文用其抓取博文资讯, 从收集器实例配置,goQuery进行dom节点数据抓取,自动分页访问,到csv数据持久化,json控制台输出,全程简单直观。

Code

抓取数据入口为社区某用户博客列表页,比如 https://learnku.com/blog/pardon

package main

import (
    "encoding/csv"
    "encoding/json"
    "log"
    "os"
    "regexp"
    "strconv"
    "strings"

    "github.com/gocolly/colly"
)

// Article 抓取blog数据
type Article struct {
    ID       int    `json:"id,omitempty"`
    Title    string `json:"title,omitempty"`
    URL      string `json:"url,omitempty"`
    Created  string `json:"created,omitempty"`
    Reads    string `json:"reads,omitempty"`
    Comments string `json:"comments,omitempty"`
    Feeds    string `json:"feeds,omitempty"`
}

// 数据持久化
func csvSave(fName string, data []Article) error {
    file, err := os.Create(fName)
    if err != nil {
        log.Fatalf("Cannot create file %q: %s\n", fName, err)
    }
    defer file.Close()
    writer := csv.NewWriter(file)
    defer writer.Flush()
    
    writer.Write([]string{"ID", "Title", "URL", "Created", "Reads", "Comments", "Feeds"})
    for _, v := range data {
        writer.Write([]string{strconv.Itoa(v.ID), v.Title, v.URL, v.Created, v.Reads, v.Comments, v.Feeds})
    }
    return nil
}

func main() {
    articles := make([]Article, 0, 200)
   // 1.准备收集器实例
    c := colly.NewCollector(
        // 开启本机debug
        // colly.Debugger(&debug.LogDebugger{}),
        colly.AllowedDomains("learnku.com"),
        // 防止页面重复下载
        // colly.CacheDir("./learnku_cache"),
    )

    // 2.分析页面数据
    c.OnHTML("div.blog-article-list > .event", func(e *colly.HTMLElement) {
        article := Article{
            Title: e.ChildText("div.content > div.summary"),
            URL:   e.ChildAttr("div.content a.title", "href"),
            Feeds: e.ChildText("div.item-meta > a:first-child"),
        }
        // 查找同一集合不同子项
        e.ForEach("div.content > div.meta > div.date>a", func(i int, el *colly.HTMLElement) {
            switch i {
            case 1:
                article.Created = el.Attr("data-tooltip")
            case 2:
                // 用空白切割字符串
                article.Reads = strings.Fields(el.Text)[1]
            case 3:
                article.Comments = strings.Fields(el.Text)[1]
            }
        })
        // 正则匹配替换,字符串转整型
        article.ID, _ = strconv.Atoi(regexp.MustCompile(`\d+`).FindAllString(article.URL, -1)[0])
        articles = append(articles, article)
    })

    // 下一页
    c.OnHTML("a[href].page-link", func(e *colly.HTMLElement) {
        e.Request.Visit(e.Attr("href"))
    })

    // 启动
    c.Visit("https://learnku.com/blog/pardon")

    // 输出
    csvSave("pardon.csv", articles)
    enc := json.NewEncoder(os.Stdout)
    enc.SetIndent("", "  ")
    enc.Encode(articles)
    
    // 显示收集器的打印信息
    log.Println(c)
}

Output

控制台输出

....
    "id": 30604,
    "title": "教程: TodoMVC 与 director 路由",
    "url": "https://learnku.com/articles/30604",
    "created": "2019-07-01 12:42:01",
    "reads": "650",
    "comments": "0",
    "feeds": "0"
  },
  {
    "id": 30579,
    "title": "flaskr 进阶笔记",
    "url": "https://learnku.com/articles/30579",
    "created": "2019-06-30 19:01:04",
    "reads": "895",
    "comments": "0",
    "feeds": "0"
  },
  {
    "id": 30542,
    "title": "教程 Redis+ flask+vue 在线聊天",
    "url": "https://learnku.com/articles/30542",
    "created": "2019-06-29 12:19:45",
    "reads": "2760",
    "comments": "1",
    "feeds": "2"
  }
]
2019/12/20 15:50:14 Requests made: 5 (5 responses) | Callbacks: OnRequest: 0, OnHTML: 2, OnResponse: 0, OnError: 0

csv 文本输出

ID,Title,URL,Created,Reads,Comments,Feeds
37991,ferret 爬取动态网页,https://learnku.com/articles/37991,2019-12-15 10:43:03,219,0,3
37803,匿名类 与 索引重建,https://learnku.com/articles/37803,2019-12-09 19:35:09,323,1,0
37476,大话并发,https://learnku.com/articles/37476,2019-12-08 21:17:55,612,0,4
37738,三元运算符,https://learnku.com/articles/37738,2019-12-08 09:44:36,606,0,0
37719,笔试之 模板变量替换,https://learnku.com/articles/37719,2019-12-07 18:30:42,843,0,0
37707,笔试之 连续数增维,https://learnku.com/articles/37707,2019-12-07 13:50:17,872,0,0
37616,笔试之 一行代码求重,https://learnku.com/articles/37616,2019-12-05 12:10:24,792,0,0
....

Colly

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