Golang爬虫框架colly使用浅析

Golang 是一门非常适合编写网络爬虫的语言，它有着高效的并发处理能力和丰富的网络编程库。下面是一个简单的 Golang 网络爬虫示例：

package main
import (
    "fmt"
    "net/http"
    "io/ioutil"
    "regexp"
)
func main() {
    resp, err := http.Get("https://www.example.com")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    defer resp.Body.Close()
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    re := regexp.MustCompile("<title>(.*)</title>")
    title := re.FindStringSubmatch(string(body))[1]
    fmt.Println("Title:", title)
}

package main
import (
  "fmt"
  colly "github.com/gocolly/colly/v2"
  "github.com/gocolly/colly/v2/debug"
)
func main() {
  mUrl := "http://www.ifeng.com/"
  //colly的主体是Collector对象，管理网络通信和负责在作业运行时执行附加的回掉函数
  c := colly.NewCollector(
    // 开启本机debug
    colly.Debugger(&debug.LogDebugger{}),
  )
  //发送请求之前的执行函数
  c.OnRequest(func(r *colly.Request) {
    fmt.Println("这里是发送之前执行的函数")
  })
  //发送请求错误被回调
  c.OnError(func(_ *colly.Response, err error) {
    fmt.Print(err)
  })
  //响应请求之后被回调
  c.OnResponse(func(r *colly.Response) {
    fmt.Println("Response body length：", len(r.Body))
  })
  //response之后会调用该函数，分析页面数据
  c.OnHTML("div#newsList h1 a", func(e *colly.HTMLElement) {
    fmt.Println(e.Text)
  })
  //在OnHTML之后被调用
  c.OnScraped(func(r *colly.Response) {
    fmt.Println("Finished", r.Request.URL)
  })
  //这里是执行访问url
  c.Visit(mUrl)
}

[000001] 1 [ 1 - request] map["url":"http://www.ifeng.com/"] (0s)
[000002] 1 [ 1 - responseHeaders] map["status":"OK" "url":"http://www.ifeng.com/"] (64.9485ms)
Response body length：250326
Finished http://www.ifeng.com/
[000003] 1 [ 1 - response] map["status":"OK" "url":"http://www.ifeng.com/"] (114.9949ms)
[000004] 1 [ 1 - html] map["selector":"div#newsList h1 a" "url":"http://www.ifeng.com/"] (118.9926ms)
[000005] 1 [ 1 - html] map["selector":"div#newsList h1 a" "url":"http://www.ifeng.com/"] (118.9926ms)
[000006] 1 [ 1 - scraped] map["url":"http://www.ifeng.com/"] (118.9926ms)