golang源码分析:chromedp

// Command click is a chromedp example demonstrating how to use a selector to
// click on an element.
package main

import (
  "context"
  "log"
  "time"

  "github.com/chromedp/chromedp"
)

func main() {
  // create chrome instance
  ctx, cancel := chromedp.NewContext(
    context.Background(),
    // chromedp.WithDebugf(log.Printf),
  )
  defer cancel()

  // create a timeout
  ctx, cancel = context.WithTimeout(ctx, 15*time.Second)
  defer cancel()

  // navigate to a page, wait for an element, click
  var example string
  err := chromedp.Run(ctx,
    chromedp.Navigate(`https://pkg.go.dev/time`),
    // wait for footer element is visible (ie, page is loaded)
    chromedp.WaitVisible(`body > footer`),
    // find and click "Example" link
    chromedp.Click(`#example-After`, chromedp.NodeVisible),
    // retrieve the text of the textarea
    chromedp.Value(`#example-After textarea`, &example),
  )
  if err != nil {
    log.Fatal(err)
  }
  log.Printf("Go's time.After example:\n%s", example)
}

2023/07/02 23:29:57 Go's time.After example:
package main

import (
        "fmt"
        "time"
)

var c chan int

func handle(int) {}

func main() {
        select {
        case m := <-c:
                handle(m)
        case <-time.After(10 * time.Second):
                fmt.Println("timed out")
        }
}

// Command cookie is a chromedp example demonstrating how to set a HTTP cookie
// on requests.
package main

import (
  "context"
  "encoding/json"
  "flag"
  "fmt"
  "log"
  "net/http"
  "time"

  "github.com/chromedp/cdproto/cdp"
  "github.com/chromedp/cdproto/network"
  "github.com/chromedp/cdproto/storage"
  "github.com/chromedp/chromedp"
)

func main() {
  port := flag.Int("port", 8544, "port")
  flag.Parse()

  // start cookie server
  go cookieServer(fmt.Sprintf(":%d", *port))

  // create context
  ctx, cancel := chromedp.NewContext(context.Background())
  defer cancel()

  // run task list
  var res string
  err := chromedp.Run(ctx, setcookies(
    fmt.Sprintf("http://localhost:%d", *port), &res,
    "cookie1", "value1",
    "cookie2", "value2",
  ))
  if err != nil {
    log.Fatal(err)
  }

  log.Printf("chrome received cookies: %s", res)
}

// cookieServer creates a simple HTTP server that logs any passed cookies.
func cookieServer(addr string) error {
  mux := http.NewServeMux()
  mux.HandleFunc("/", func(res http.ResponseWriter, req *http.Request) {
    cookies := req.Cookies()
    for i, cookie := range cookies {
      log.Printf("from %s, server received cookie %d: %v", req.RemoteAddr, i, cookie)
    }
    buf, err := json.MarshalIndent(req.Cookies(), "", "  ")
    if err != nil {
      http.Error(res, err.Error(), http.StatusInternalServerError)
      return
    }
    fmt.Fprintf(res, indexHTML, string(buf))
  })
  return http.ListenAndServe(addr, mux)
}

// setcookies returns a task to navigate to a host with the passed cookies set
// on the network request.
func setcookies(host string, res *string, cookies ...string) chromedp.Tasks {
  if len(cookies)%2 != 0 {
    panic("length of cookies must be divisible by 2")
  }
  return chromedp.Tasks{
    chromedp.ActionFunc(func(ctx context.Context) error {
      // create cookie expiration
      expr := cdp.TimeSinceEpoch(time.Now().Add(180 * 24 * time.Hour))
      // add cookies to chrome
      for i := 0; i < len(cookies); i += 2 {
        err := network.SetCookie(cookies[i], cookies[i+1]).
          WithExpires(&expr).
          WithDomain("localhost").
          WithHTTPOnly(true).
          Do(ctx)
        if err != nil {
          return err
        }
      }
      return nil
    }),
    // navigate to site
    chromedp.Navigate(host),
    // read the returned values
    chromedp.Text(`#result`, res, chromedp.ByID, chromedp.NodeVisible),
    // read network values
    chromedp.ActionFunc(func(ctx context.Context) error {
      cookies, err := storage.GetCookies().Do(ctx)
      if err != nil {
        return err
      }

      for i, cookie := range cookies {
        log.Printf("chrome cookie %d: %+v", i, cookie)
      }

      return nil
    }),
  }
}

const (
  indexHTML = `<!doctype html>
<html>
<body>
  <div id="result">%s</div>
</body>
</html>`
)