chromedp模拟浏览器基础入门

    opts := append(chromedp.DefaultExecAllocatorOptions[:],
        chromedp.Flag("headless", false),  // 不开启图像界面
        chromedp.ProxyServer("http://10.10.1.1:21869"), // 设置代理访问
        chromedp.Flag("mute-audio", false), // 关闭声音
    )
    allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
    defer cancel()

熟悉最常用的几个方法：

chromedp.NewContext() 初始化chromedp的上下文，后续这个页面都使用这个上下文进行操作

chromedp.Run() 运行一个chrome的一系列操作

chromedp.Navigate() 将浏览器导航到某个页面

chromedp.WaitVisible() 等候某个元素可见，再继续执行。

chromedp.Click() 模拟鼠标点击某个元素

chromedp.Value() 获取某个元素的value值

chromedp.ActionFunc() 再当前页面执行某些自定义函数

chromedp.Text() 读取某个元素的text值

chromedp.Evaluate() 执行某个js，相当于控制台输入js

network.SetExtraHTTPHeaders() 截取请求，额外增加header头

chromedp.SendKeys() 模拟键盘操作，输入字符

chromedp.Nodes() 根据xpath获取某些元素，并存储进入数组

chromedp.NewRemoteAllocator

chromedp.OuterHTML() 获取元素的outer html

chromedp.Screenshot() 根据某个元素截图

page.CaptureScreenshot() 截取整个页面的元素

chromedp.Submit() 提交某个表单

chromedp.WaitNotPresent() 等候某个元素不存在，比如“正在搜索。。。”

package main

import (
    "context"
    "log"
    "time"

    "github.com/chromedp/chromedp"
)

func main() {

    // 禁用chrome headless
    opts := append(chromedp.DefaultExecAllocatorOptions[:],
        chromedp.Flag("headless", false),
    )
    allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
    defer cancel()

    // create chrome instance
    ctx, cancel := chromedp.NewContext(
        allocCtx,
        chromedp.WithLogf(log.Printf),
    )
    defer cancel()

    // create a timeout
    ctx, cancel = context.WithTimeout(ctx, 5*time.Second)
    defer cancel()

    // navigate to a page, wait for an element, click
    var example string
    sel := `//*[@id="username"]`
    err := chromedp.Run(ctx,
        chromedp.Navigate(`https://github.com/awake1t`),
        chromedp.WaitVisible("body"),
        //缓一缓
        chromedp.Sleep(2*time.Second),

        chromedp.SendKeys(sel, "username", chromedp.BySearch), //匹配xpath

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

    log.Printf("Go's time.After example:\n%s", example)

}

package main

import (
    "context"
    "io/ioutil"
    "log"
    "math"
    "time"

    "github.com/chromedp/cdproto/emulation"
    "github.com/chromedp/cdproto/page"
    "github.com/chromedp/chromedp"
)

func main() {

    // 禁用chrome headless
    opts := append(chromedp.DefaultExecAllocatorOptions[:],
        chromedp.Flag("headless", false),
    )
    allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
    defer cancel()

    // create chrome instance
    ctx, cancel := chromedp.NewContext(
        allocCtx,
        chromedp.WithLogf(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

    // capture screenshot of an element
    var buf []byte
    // capture entire browser viewport, returning png with quality=90
    if err := chromedp.Run(ctx, fullScreenshot(`https://github.com/awake1t`, 90, &buf)); err != nil {
        log.Fatal(err)
    }
    if err := ioutil.WriteFile("./Screenshot.png", buf, 0644); err != nil {
        log.Fatal(err)
    }
    log.Println("图片写入完成")

}

// fullScreenshot takes a screenshot of the entire browser viewport.
// Liberally copied from puppeteer's source.
// Note: this will override the viewport emulation settings.
func fullScreenshot(urlstr string, quality int64, res *[]byte) chromedp.Tasks {
    return chromedp.Tasks{
        chromedp.Navigate(urlstr),
        chromedp.ActionFunc(func(ctx context.Context) error {
            // get layout metrics
            _, _, contentSize, err := page.GetLayoutMetrics().Do(ctx)
            if err != nil {
                return err
            }

            width, height := int64(math.Ceil(contentSize.Width)), int64(math.Ceil(contentSize.Height))

            // force viewport emulation
            err = emulation.SetDeviceMetricsOverride(width, height, 1, false).
                WithScreenOrientation(&emulation.ScreenOrientation{
                    Type:  emulation.OrientationTypePortraitPrimary,
                    Angle: 0,
                }).
                Do(ctx)
            if err != nil {
                return err
            }

            // capture screenshot
            *res, err = page.CaptureScreenshot().
                WithQuality(quality).
                WithClip(&page.Viewport{
                    X:      contentSize.X,
                    Y:      contentSize.Y,
                    Width:  contentSize.Width,
                    Height: contentSize.Height,
                    Scale:  1,
                }).Do(ctx)
            if err != nil {
                return err
            }
            return nil
        }),
    }
}