Selenium 下载与浏览器中不同的验证码图像

Question

我正在尝试使用 Selenium 下载验证码图像，但是，我下载的图像与浏览器中显示的图像不同。 如果我尝试再次下载图像，而不更改浏览器，我会得到一个不同的。

有什么想法吗？

from selenium import webdriver
import urllib


driver = webdriver.Firefox()
driver.get("http://sistemas.cvm.gov.br/?fundosreg")

# Change frame.
driver.switch_to.frame("Main")


# Download image/captcha.
img = driver.find_element_by_xpath(".//*[@id='trRandom3']/td[2]/img")
src = img.get_attribute('src')
urllib.request.urlretrieve(src, "captcha.jpeg")

Answer 1

因为图像的src 的链接在您打开该链接后会给您一个随机的新验证码图像！

除了从图片的src 下载文件外，您还可以截屏以在浏览器中获取该文件。不过需要下载Pillow(pip install Pillow)，按照this answer中提到的方式使用：

from PIL import Image
from selenium import webdriver

def get_captcha(driver, element, path):
    # now that we have the preliminary stuff out of the way time to get that image :D
    location = element.location
    size = element.size
    # saves screenshot of entire page
    driver.save_screenshot(path)

    # uses PIL library to open image in memory
    image = Image.open(path)

    left = location['x']
    top = location['y'] + 140
    right = location['x'] + size['width']
    bottom = location['y'] + size['height'] + 140

    image = image.crop((left, top, right, bottom))  # defines crop points
    image.save(path, 'jpeg')  # saves new cropped image


driver = webdriver.Firefox()
driver.get("http://sistemas.cvm.gov.br/?fundosreg")

# change frame
driver.switch_to.frame("Main")

# download image/captcha
img = driver.find_element_by_xpath(".//*[@id='trRandom3']/td[2]/img")
get_captcha(driver, img, "captcha.jpeg")



driver = webdriver.Firefox()
driver.get("http://sistemas.cvm.gov.br/?fundosreg")

# change frame
driver.switch_to.frame("Main")

# download image/captcha
img = driver.find_element_by_xpath(".//*[@id='trRandom3']/td[2]/img")
get_captcha(driver, img, "captcha.jpeg")

（请注意，我已经稍微更改了代码，以便它适用于您的情况。）

Answer 2

您可以使用一段 Javascript 获取验证码的渲染图像。它比截取和裁剪屏幕截图更快：

import base64
from selenium import webdriver

driver = webdriver.Firefox()
driver.set_script_timeout(10)

driver.get("http://sistemas.cvm.gov.br/?fundosreg")

driver.switch_to.frame("Main")

# find the captcha element
ele_captcha = driver.find_element_by_xpath("//img[contains(./@src, 'RandomTxt.aspx')]")

# get the captcha as a base64 string
img_captcha_base64 = driver.execute_async_script("""
    var ele = arguments[0], callback = arguments[1];
    ele.addEventListener('load', function fn(){
      ele.removeEventListener('load', fn, false);
      var cnv = document.createElement('canvas');
      cnv.width = this.width; cnv.height = this.height;
      cnv.getContext('2d').drawImage(this, 0, 0);
      callback(cnv.toDataURL('image/jpeg').substring(22));
    }, false);
    ele.dispatchEvent(new Event('load'));
    """, ele_captcha)

# save the captcha to a file
with open(r"captcha.jpg", 'wb') as f:
    f.write(base64.b64decode(img_captcha_base64))

Answer 3

如果您已经加载了图像，而不是 execute_async_script，请使用

import base64
img_base64 = browser.execute_script("""
    var ele = arguments[0];
    var cnv = document.createElement('canvas');
    cnv.width = ele.width; cnv.height = ele.height;
    cnv.getContext('2d').drawImage(ele, 0, 0);
    return cnv.toDataURL('image/jpeg').substring(22);    
    """, browser.find_element_by_xpath("//your_xpath"))
with open(r"image.jpg", 'wb') as f:
    f.write(base64.b64decode(img_base64))