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Go1.19 crawler compage: simpliciorem reddere automated reptans situs templates

2024-07-12

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introductio

Tela Scraper instrumentum est quod statim notitias e websites extrahit. Late usi sunt in notitia collectionis, inquisitionis optimiizationis, investigationis mercatus et aliorum agrorum. Articulus hic singillatim introducebit quomodo utatur Go 1.19 ad efficiendum simpliciorem locum automated template reptans instrumentum ad auxilium tincturae colligere notitia efficienter.

Tabula contentorum

  1. Praeparatio Environmental
  2. Praecipuae notiones interretiales reptilia
  3. Ite reptans compage lectio
  4. Basic processus designing a crawler
  5. Simplex efficiendi telam crawler
  6. Parse HTML content
  7. Concurrency processus of crawlers
  8. notitia repono
  9. Error pertractatio et Retry mechanism
  10. Casus practicus: reptans nuntium websites
  11. Provectus features and optimizations
  12. finitione

1. Praeparatio Opera

Priusquam incipias, fac te Ire 1.19 institutum in systemate tuo. Ite versionem cum imperio sequenti potes reprehendo:

go version

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Si nondum inauguratus es Ite adhuc, extrahere potes Ite rutrum Download and install the latest version.

2. Praecipuae notiones interretiales reptilia

Fundamentalis fluxus interretiantis talis est:

  1. mittam petitionem: Rogationem HTTP ad scopum paginae mitte.
  2. Get responsum: Accipe responsum HTTP a servo redditum.
  3. parse content: Extract ex responsione data inquisita.
  4. Thesaurizantes data: Serva data extracta ad fasciculum localem vel datorum.
  5. Palpate nexus: Nexus e paginis excerptis et alias paginas repere pergunt.

3. Ite crawler compage lectio

In lingua Ire plura sunt compages vulgaris reptans, ut:

  • Colly: Ieiunium et elegans compage reptans, quod dives functionality et bonum perficiendi praebet.
  • Goquery: A jQuery-like library for parsing and manipulating HTML documents.
  • HTTP client: Rete/http sarcina normae bibliothecae simplicissimae HTTP postulationi occurrere potest.

Hic articulus maxime Colly et Goquery utetur ad interretiales et contentos parsing.

4. Basic processus designandi a crawler

Formam simpliciorem automated instrumentum situs reptans designabimus. Processus fundamentalis talis est:

  1. Configuratione initialize crawler.
  2. Rogationem HTTP mitte ut pagina contenta obtineatur.
  3. Goquery utere ad HTML contentum parse et data requisita extrahendi.
  4. Serva data ad locum fasciculi vel database.
  5. Erroris tractatio et retry machinationes.
  6. Utere processui concurrentes ad efficientiam reptantium emendandam.

5. deducendi simplici telam crawler

Primum, novum consilium crea;

mkdir go_scraper
cd go_scraper
go mod init go_scraper

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Deinde, Colly et Goquery install:

go get -u github.com/gocolly/colly
go get -u github.com/PuerkitoBio/goquery

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Deinde scribe simplicem trahentem ad contenta telae repere:

package main

import (
    "fmt"
    "github.com/gocolly/colly"
)

func main() {
    // 创建一个新的爬虫实例
    c := colly.NewCollector()

    // 设置请求时的回调函数
    c.OnRequest(func(r *colly.Request) {
        fmt.Println("Visiting", r.URL.String())
    })

    // 设置响应时的回调函数
    c.OnResponse(func(r *colly.Response) {
        fmt.Println("Visited", r.Request.URL)
        fmt.Println("Response:", string(r.Body))
    })

    // 设置错误处理的回调函数
    c.OnError(func(r *colly.Response, err error) {
        fmt.Println("Error:", err)
    })

    // 设置HTML解析时的回调函数
    c.OnHTML("title", func(e *colly.HTMLElement) {
        fmt.Println("Title:", e.Text)
    })

    // 开始爬取
    c.Visit("http://example.com")
}

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Praedictus currens codice contentum http://example.com nudabit et titulum paginae imprimet.

6. Parse HTML content

Ut data inquisita ex pagina extrahantur, opus est Goquery uti ad contentum HTML parse. Hoc exemplum ostendit quomodo Goquery utatur ad nexus et textum e pagina extrahendum:

package main

import (
    "fmt"
    "github.com/gocolly/colly"
    "github.com/PuerkitoBio/goquery"
)

func main() {
    c := colly.NewCollector()

    c.OnHTML("body", func(e *colly.HTMLElement) {
        e.DOM.Find("a").Each(func(index int, item *goquery.Selection) {
            link, _ := item.Attr("href")
            text := item.Text()
            fmt.Printf("Link #%d: %s (%s)n", index, text, link)
        })
    })

    c.Visit("http://example.com")
}

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7. Concurrentes processus of crawlers

Ut ad efficientiam trahentis melioretur, uti possumus munus concursus Colly:

package main

import (
    "fmt"
    "github.com/gocolly/colly"
    "github.com/PuerkitoBio/goquery"
    "log"
    "time"
)

func main() {
    c := colly.NewCollector(
        colly.Async(true), // 启用异步模式
    )

    c.Limit(&colly.LimitRule{
        DomainGlob:  "*",
        Parallelism: 2, // 设置并发数
        Delay:       2 * time.Second,
    })

    c.OnHTML("body", func(e *colly.HTMLElement) {
        e.DOM.Find("a").Each(func(index int, item *goquery.Selection) {
            link, _ := item.Attr("href")
            text := item.Text()
            fmt.Printf("Link #%d: %s (%s)n", index, text, link)
            c.Visit(e.Request.AbsoluteURL(link))
        })
    })

    c.OnRequest(func(r *colly.Request) {
        fmt.Println("Visiting", r.URL.String())
    })

    c.OnError(func(r *colly.Response, err error) {
        log.Println("Error:", err)
    })

    c.Visit("http://example.com")

    c.Wait() // 等待所有异步任务完成
}

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8. Data repono

Servo datam captam ad fasciculum localem vel database. Hic fasciculus CSV exemplum:

package main

import (
    "encoding/csv"
    "fmt"
    "github.com/gocolly/colly"
    "github.com/PuerkitoBio/goquery"
    "log"
    "os"
    "time"
)

func main() {
    file, err := os.Create("data.csv")
    if err != nil {
        log.Fatalf("could not create file: %v", err)
    }
    defer file.Close()

    writer := csv.NewWriter(file)
    defer writer.Flush()

    c := colly.NewCollector(
        colly.Async(true),
    )

    c.Limit(&colly.LimitRule{
        DomainGlob:  "*",
        Parallelism: 2,
        Delay:       2 * time.Second,
    })

    c.OnHTML("body", func(e *colly.HTMLElement) {
        e.DOM.Find("a").Each(func(index int, item *goquery.Selection) {
            link, _ := item.Attr("href")
            text := item.Text()
            fmt.Printf("Link #%d: %s (%s)n", index, text, link)
            writer.Write([]string{text, link})
            c.Visit(e.Request.AbsoluteURL(link))
        })
    })

    c.OnRequest(func(r *colly.Request) {
        fmt.Println("Visiting", r.URL.String())
    })

    c.OnError(func(r *colly.Response, err error) {
        log.Println("Error:", err)
    })

    c.Visit("http://example.com")

    c.Wait()
}

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9. Error pertractatio et Retry mechanism

Ut ad stabilitatem trahentis melioretur, necesse est ut errores petant et retry mechanismum efficiant;

package main

import (
    "fmt"
    "github.com/gocolly/colly"
    "github.com/PuerkitoBio/goquery"
    "log"
    "os"
    "time"
)

func main() {
    file, err := os.Create("data.csv")
    if err != nil {
        log.Fatalf("could not create file: %v", err)
    }
    defer file.Close()

    writer := csv.NewWriter(file)
    defer writer.Flush()

    c := colly.NewCollector(
        colly.Async(true),
        colly.MaxDepth(1),
    )

    c.Limit(&colly.LimitRule{
        DomainGlob:  "*",
        Parallelism: 2,
        Delay:       2 * time.Second,
    })

    c.OnHTML("body", func(e *colly.HTMLElement) {
        e.DOM.Find("a").Each(func(index int, item *goquery.Selection) {
            link, _ := item.Attr("href")
            text := item.Text()
            fmt.Printf("Link #%d: %s (%s)

n", index, text, link)
            writer.Write([]string{text, link})
            c.Visit(e.Request.AbsoluteURL(link))
        })
    })

    c.OnRequest(func(r *colly.Request) {
        fmt.Println("Visiting", r.URL.String())
    })

    c.OnError(func(r *colly.Response, err error) {
        log.Println("Error:", err)
        // 重试机制
        if r.StatusCode == 0 || r.StatusCode >= 500 {
            r.Request.Retry()
        }
    })

    c.Visit("http://example.com")

    c.Wait()
}

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10. De casu: reptans nuntium websites

Hoc exemplum ostendit quomodo titulos et nexus percontationum rasurarum et in fasciculo CSV servaveris:

package main

import (
    "encoding/csv"
    "fmt"
    "github.com/gocolly/colly"
    "log"
    "os"
    "time"
)

func main() {
    file, err := os.Create("news.csv")
    if err != nil {
        log.Fatalf("could not create file: %v", err)
    }
    defer file.Close()

    writer := csv.NewWriter(file)
    defer writer.Flush()

    writer.Write([]string{"Title", "Link"})

    c := colly.NewCollector(
        colly.Async(true),
    )

    c.Limit(&colly.LimitRule{
        DomainGlob:  "*",
        Parallelism: 5,
        Delay:       1 * time.Second,
    })

    c.OnHTML(".news-title", func(e *colly.HTMLElement) {
        title := e.Text
        link := e.ChildAttr("a", "href")
        writer.Write([]string{title, e.Request.AbsoluteURL(link)})
        fmt.Printf("Title: %snLink: %sn", title, e.Request.AbsoluteURL(link))
    })

    c.OnRequest(func(r *colly.Request) {
        fmt.Println("Visiting", r.URL.String())
    })

    c.OnError(func(r *colly.Response, err error) {
        log.Println("Error:", err)
        if r.StatusCode == 0 || r.StatusCode >= 500 {
            r.Request.Retry()
        }
    })

    c.Visit("http://example-news-site.com")

    c.Wait()
}

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11. Provectus functiones et optimizations

Utere procuratorem

Ad ne interclusus a website scopo, procuratorem uti potes:

c.SetProxy("http://proxyserver:port")

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User agente transgredi

Fingunt aliud esse navigatrum ponendo utentis agentis:

c.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3"

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Distribuit crawler

Potes uti bibliotheca Colly-Redis extensione Colly-Redis ad efficiendum reptilia distributa:

import (
    "github.com/gocolly/redisstorage"
)

func main() {
    c := colly.NewCollector()
    redisStorage := &redisstorage.Storage{
        Address:  "localhost:6379",
        Password: "",
        DB:       0,
        Prefix:   "colly",
    }
    c.SetStorage(redisStorage)
}

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Dynamica tela rasurae

Ad paginas dynamicas, sine capite navigatro uti potes ut chromedp:

import (
    "context"
    "github.com/chromedp/chromedp"
)

func main() {
    ctx, cancel := chromedp.NewContext(context.Background())
    defer cancel()

    var res string
    err := chromedp.Run(ctx,
        chromedp.Navigate("http://example.com"),
        chromedp.WaitVisible(`#some-element`),
        chromedp.InnerHTML(`#some-element`, &res),
    )

    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(res)
}

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12. Conclusio

Per accuratam huius articuli introductionem didicimus uti Go 1.19 ad efficiendum simpliciorem automated locum templates reptans instrumentum. Processus designati a basic trahens incepimus et paulatim in aspectus claves venimus ut parsing HTML, processus concurrentis, notitia repono et errorum tractatio, et demonstravimus quomodo perrepere ac percurrere notitias interretiales per exempla certa codicis.

The Go linguae validae concursus processus facultatum ac locuples bibliothecae tertiae factionis eam faciunt optimam electionem ad efficaces et stabilis interretiales reptilia aedificandi. Per continuam optimizationem et dilatationem, functiones magis implicatae et provectae reptans fieri possunt ut solutiones pro variis notitiarum collectionibus necessitatibus provideant.

Spero hunc articulum tibi valide referendum praebere ad exsequendam lingua reptilia in Go et inspirare te ad explorationem et innovationem magis in hoc campo peragendam.

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