基于Go语言和phantomJS的屏幕截图分享微服务

背景

• 前端程序员不愿意(技术不行)使用canvs截取图片分享到微信朋友圈

准备工作

• *unix系统安装phantomJS可执行文件,phantomjs添加到系统环境变量
• 检验phantomjs安装是否成功,在终端中运行$: phantomjs不报错,则安装成功
• 安装go package github.com/benbjohnson/phantomjs,主要功能方便go调用phantomJS二进制文件命令

go调用phantomJS代码解析

• defer函数捕捉panic

  func main() {
      defer func(){
  
          err:= recover()
          if err != nil {
              println(err)
          }
      }()
      var url = "https://www.163.com"

• 创建一个在golang里面phantomJS创建一个phanomJS进程

  if err := phantomjs.DefaultProcess.Open(); err != nil {
      panic(err)
      os.Exit(1)
  }
  defer phantomjs.DefaultProcess.Close()

• 创建phantomJS page设置请求headers和view port

  page, err := phantomjs.CreateWebPage()
  if err != nil {
      panic(err)
  }
  //set request headers 设置UserAgent为iPhone
  requestHeader := http.Header{
      "User-Agent" :[]string{"Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1"},
  }
  
  if err := page.SetCustomHeaders(requestHeader);err != nil {
      panic(err)
  }
  
  // Setup the viewport and render the results view.
  if err := page.SetViewportSize(640, 960); err != nil {
      panic(err)
  }

• 截图并输出png文件

  // Open a URL.
  if err := page.Open(url); err != nil {
      panic(err)
  }
  if err := page.Render("hackernews4.png", "png", 50); err != nil {
      panic(err)
  }}

• 完整代码
  main.go

    package main
  
    import (
        "github.com/benbjohnson/phantomjs"
        "os"
        "net/http"
    )
    
    //https://github.com/benbjohnson/phantomjs
    func main() {
        defer func(){
    
            err:= recover()
            if err != nil {
                println(err)
            }
        }()
    
        var url = "https://www.163.com"
        // Start the process once.
        if err := phantomjs.DefaultProcess.Open(); err != nil {
            panic(err)
            os.Exit(1)
        }
    
        defer phantomjs.DefaultProcess.Close()
    
    
        page, err := phantomjs.CreateWebPage()
        if err != nil {
            panic(err)
        }
        //set request headers
        requestHeader := http.Header{
            "User-Agent" :[]string{"Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1"},
        }
    
        if err := page.SetCustomHeaders(requestHeader);err != nil {
            panic(err)
        }
    
        // Setup the viewport and render the results view.
        if err := page.SetViewportSize(640, 960); err != nil {
            panic(err)
        }
        // Open a URL.
        if err := page.Open(url); err != nil {
            panic(err)
        }
        if err := page.Render("163_news_screen_shot.png", "png", 50); err != nil {
            panic(err)
        }}

使用go标准库创建截图微服务

• main.go完成代码

    // example of HTTP server that uses the captcha package.
package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "os"
    "github.com/benbjohnson/phantomjs"
)

const OutputDir = "screen_shot"

//ConfigJsonBody json request body.
type jsonBody struct {
    Url              string `json:"url"`
    ViewportWidth     int `json:"viewport_width"`
    ViewportHeight     int `json:"viewport_height"`
    OutputFileName     string `json:"output_file_name"`
    OutputFileExt     string  `json:"output_file_ext"`
    Quility int `json:"quility"`
    OutputUri    string `json:"output_uri"`
}

// base64Captcha create http handler
func screen_shot(w http.ResponseWriter, r *http.Request) {
    //parse request parameters
    //接收客户端发送来的请求参数json
    decoder := json.NewDecoder(r.Body)
    var postParameters jsonBody
    err := decoder.Decode(&postParameters)
    if err != nil {
        log.Println(err)
    }
    defer r.Body.Close()
    //截图网页
    phantomjs_screen_shot(&postParameters)
    //set json response
    //设置json响应
    w.Header().Set("Content-Type", "application/json; charset=utf-8")
    body := map[string]interface{}{"code": 1, "data": postParameters, "msg": "success"}
    json.NewEncoder(w).Encode(body)
}

func phantomjs_screen_shot(config *jsonBody)  {
    uri := fmt.Sprintf("%s/%s", OutputDir,config.OutputFileName)
    config.OutputFileName = uri
    config.OutputUri = uri
    // Start the process once.
    if err := phantomjs.DefaultProcess.Open(); err != nil {
        panic(err)
        os.Exit(1)
    }
    defer phantomjs.DefaultProcess.Close()


    page, err := phantomjs.CreateWebPage()
    if err != nil {
        panic(err)
    }
    //set request headers
    requestHeader := http.Header{
        "User-Agent" :[]string{"Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1"},
    }

    if err := page.SetCustomHeaders(requestHeader);err != nil {
        panic(err)
    }

    // Setup the viewport and render the results view.
    if err := page.SetViewportSize(config.ViewportWidth, config.ViewportHeight); err != nil {
        panic(err)
    }
    // Open a URL.
    if err := page.Open(config.Url); err != nil {
        panic(err)
    }
    if err := page.Render(config.OutputFileName, config.OutputFileExt, config.Quility); err != nil {
        panic(err)
    }
}


//start a net/http server
//启动golang net/http 服务器
func main() {
    
    pathPrefix := "/"+OutputDir +"/"
    staticDir := "./"+OutputDir
    http.Handle(pathPrefix,http.StripPrefix(pathPrefix, http.FileServer(http.Dir(staticDir))))

    //api for create captcha
    http.HandleFunc("/api/shot", screen_shot)


    fmt.Println("Server is at localhost:1122")
    if err := http.ListenAndServe("localhost:1122", nil); err != nil {
        log.Fatal(err)
    }
}

• postmanAPI接口

POST /api/shot HTTP/1.1
Host: localhost:1122
Content-Type: application/json
Cache-Control: no-cache

{
    "url":"http://www.163.com",
    "viewport_width":480,
    "viewport_height":960,
    "output_file_name":"awesome.jpg",
    "output_file_ext":"jpg",
    "quility":90
}
- 返回参数

{

"code": 1,
"data": {
    "url": "http://www.163.com",
    "viewport_width": 480,
    "viewport_height": 960,
    "output_file_name": "screen_shot/awesome.jpg",
    "output_file_ext": "jpg",
    "quility": 90,
    "output_uri": "screen_shot/awesome.jpg"
},
"msg": "success"

}

截图图片地址`localhost:1122/` + `output_uri`

使用chromedp 替换phantomjs

欢迎来到我的技术博客mojotv

GitHub源码地址