Henry Litvin
Henry Litvin
1月前 · 1 人阅读

大家好,我叫谢伟,是一名程序员。

我们已经研究了:

今天的主题:Go 语言语法练习。

我们需要达到一个什么样的目的:目标网站 gocn,抓取所有信息,以我们需要的形式返回信息。

具体结果是这样的:http://localhost:8080/gocn/api/v1/tenants/contents/{page}

项目虽然小,但是有几个要点:

  • 项目的组织
  • go 爬虫
  • restful api 设计

尤其是 restful api 设计,在微服务领域,经常要设计一个组件,提供一些服务,各服务之间通过接口相互访问,同时对组件的编程语言、架构都没有要求,只对外暴露出现接口即可,通过接口访问,组件内部进行相应的处理。

这里我们不细讲,下次专门讲下 restful api 的设计:包括 HTTP 路由设计、状态码设计、返回值设计、错误信息设计。

1. 项目组织

workspace
   domain
       objects.go
   download
      download.go
   engine
      engine.go
  infra
     util_string.go
  main
    main.go
  parse
    gocn
        gocn_parse.go
  ui
    api-server
       api-server.go
       route_function.go

2. 定义字段

domain
   objects.go

定义抓取的字段:

type Content struct {
    URL          string
    Title        string
    Tag          string
    Reporter     string
    ReporterHome string
    Followers    int
    Answers      int
    Answerer     string
    See          int
    Passage      string
}

问题链接、标题、所属板块、楼主、楼主主页、关注数、回复数、浏览数、正文

3. 下载器

   download
      download.go
package download

import (
    "net/http"

    "errors"

    "github.com/PuerkitoBio/goquery"
)

var (
    ErrorHttpRequest  = errors.New("http request error")
    ErrorHttpResponse = errors.New("http response error")
)

func Download(url string) (*goquery.Document, error) {
    var (
        req *http.Request
        err error
    )
    if req, err = http.NewRequest("GET", url, nil); err != nil {
        return nil, ErrorHttpRequest
    }

    client := http.DefaultClient
    req.Header.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36")
    var (
        resp *http.Response
    )
    if resp, err = client.Do(req); err != nil {
        return nil, ErrorHttpResponse
    }

    defer resp.Body.Close()

    return goquery.NewDocumentFromReader(resp.Body)
}

  • 使用了内置的 net/http 库
  • 使用了第三方库 goquery ,主要是它很好的对网页解析

4. 解析器

  parse
    gocn
        gocn_parse.go
package gocn

import (
    "errors"

    "go-example-for-live/nine_learning/infra"

    "go-example-for-live/nine_learning/download"

    "go-example-for-live/nine_learning/domain"

    "github.com/PuerkitoBio/goquery"
)

var (
    ErrorParse = errors.New("parse error")
)

func TitleParse(document *goquery.Document) domain.Contents {

    var (
        AllContents domain.Contents
        OneContent  domain.Content
    )

    document.Find("div.aw-common-list div.aw-item").Each(func(i int, selection *goquery.Selection) {
        var (
            user           string
            userHome       string
            url            string
            passageContent string
            title          string
            tag            string
            lastAnswer     string
            one            int
            two            int
            three          int
        )
        user = infra.StringSplit(selection.Find("a").Eq(0).AttrOr("href", "None"))
        userHome = selection.Find("a").Eq(0).AttrOr("href", "None")
        url = selection.Find("div h4 a").AttrOr("href", "None")
        doc, _ := download.Download(url)
        passageContent, _ = PassageParse(doc)
        title = infra.StringTrim(selection.Find("div h4").Text())
        tag = selection.Find("p a").Eq(0).Text()
        lastAnswer = selection.Find("p a").Eq(1).Text()
        one, two, three = infra.StringSplitByDot(selection.Find("p span").Eq(0).Text())
        //fmt.Println(user, userHome, url, title, tag, lastAnswer, one, two, three, passageContent)

        OneContent = domain.Content{
            URL:          url,
            Title:        title,
            Tag:          tag,
            Reporter:     user,
            ReporterHome: userHome,
            Followers:    one,
            Answers:      two,
            Answerer:     lastAnswer,
            See:          three,
            Passage:      passageContent,
        }
        //fmt.Println(OneContent)
        AllContents = append(AllContents, OneContent)

    })
    return AllContents

}

func PassageParse(document *goquery.Document) (string, error) {
    var content string
    content = infra.StringTrim(document.Find("div.content.markitup-box").Text())
    return infra.StringsReplace(content), nil
}

  • PassageParse 获取正文
  • TitleParse 解析其他字段

5. 调度引擎

   engine
      engine.go
package engine

import (
    "errors"
    "go-example-for-live/nine_learning/download"

    "fmt"

    "go-example-for-live/nine_learning/parse/gocn"

    "go-example-for-live/nine_learning/domain"

    "github.com/PuerkitoBio/goquery"
)

var (
    ErrorRun = errors.New("engine error")
)

var (
    ContentsNil = domain.Contents{}
)

func Run(request domain.Request) (domain.Contents, error) {

    var (
        doc *goquery.Document
        err error
    )
    if doc, err = download.Download(request.Url); err != nil {
        fmt.Println(err)
        return ContentsNil, ErrorRun
    }

    return gocn.TitleParse(doc), nil

}

6. api 服务

  ui
    api-server
       api-server.go
       route_function.go
package apiserver

import (
    "log"
    "net/http"

    "github.com/emicklei/go-restful"
)

type APIServer struct {
    container *restful.Container
}

type APIServers []APIServer

func (a *APIServer) init() {
    wsContainer := restful.NewContainer()
    wsContainer.EnableContentEncoding(true)
    wsContainer.Router(restful.CurlyRouter{})
    a.container = wsContainer
}

func (a *APIServer) register() {
    ws := new(restful.WebService)
    ws.Consumes(restful.MIME_JSON)
    ws.Produces(restful.MIME_JSON)

    ws.Path("/gocn")
    ws.Route(ws.GET("/api/v1/tenants/contents/{page}").To(GetContents))

    a.container.Add(ws)

}

func (a *APIServer) Start() {
    server := &http.Server{Addr: ":8080", Handler: a.container}
    log.Fatal(server.ListenAndServe())
}

func New() *APIServer {
    apiServer := &APIServer{container: nil}
    apiServer.init()
    apiServer.register()
    return apiServer
}

package apiserver

import (
    "go-example-for-live/nine_learning/domain"
    "go-example-for-live/nine_learning/engine"
    "go-example-for-live/nine_learning/parse/gocn"

    "fmt"

    "github.com/emicklei/go-restful"
)

var (
    startURL = "https://gocn.io/sort_type-new__day-0__is_recommend-0"
    rootURL  = "https://gocn.io/sort_type-new__day-0__is_recommend-0__page-%s"
)

func GetContents(request *restful.Request, response *restful.Response) {
    var (
        page string
        url  string
    )
    page = request.PathParameter("page")
    if page == "" {
        url = startURL
    } else {
        url = fmt.Sprintf(rootURL, page)
    }
    contents, _ := engine.Run(
        domain.Request{
            Url:       url,
            ParseFunc: gocn.TitleParse,
        },
    )
    response.WriteEntity(contents)
}

  • 使用了go-restful 库
  • http 主要包含这么几个东西
1. http 方法
2. request 
3. reponse

7. 主函数入口

main
   main.go
package main

import "go-example-for-live/nine_learning/ui/api-server"

func main() {
    apiserver.New().Start()

}

启动http 服务,监听8080 端口。

8. 访问

http://localhost:8080/gocn/api/v1/tenants/contents/{page}

访问源代码:https://github.com/wuxiaoxiaoshen/go-example-for-live

通过本节,希望你能知道,如何组织项目结构,go 常用的用法:变量的用法、错误处理机制、结构体定义、结构体方法、第三方库的使用。

再会,我是谢伟。

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