Python数据分析及可视化实例之Selenium、PantomJS

Python数据分析及可视化实例之Selenium、PantomJS

系列文章总目录:Python数据分析及可视化实例目录


一直以来我觉得用在运维的Selenium、PantomJS是一个重器,

不到万不得已的时候不要祭出这个大杀器,

但是涉及到JavaScript及Ajax渲染的时候,Requests就完全懵逼了!


最近回过头来重新审视这货,

这个重器用反倒轻便了很多。


1.安装Selenium、PantomJS

Selenium可以直接通过pip安装,PantomJS则是一个exe可执行文件,需要下载解压。在使用的时候指定exe的绝对路径即可。

2.Selenium、PantomJS基本设置

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
dcap = DesiredCapabilities.PHANTOMJS
dcap[ "phantomjs.page.settings.userAgent"] = "Mozilla / 4.0(Windows NT 10.0; Win64;x64) AppleWebKit / 537.36(KHTML, like Gecko) Chrome/51.0.2704.79 Safari/ 537.36Edge/14.14393"
# 请求头不一样,自适应的窗口不一样,卧槽,坑爹!
driver = webdriver.PhantomJS(desired_capabilities=dcap)
driver.set_page_load_timeout(10)
driver.set_script_timeout(10) # 设置页面退出时间,没有必要等一个网页加载完了采集
# 采集网页源码
    try:
        driver.get(inurl)
        content = driver.page_source
        # print(content)
        time.sleep(1)
    except:
        driver.execute_script('window.stop()')
driver.close()


3.Selenium、PantomJS基本操作

如果你的网络和机子足够好,基本上就不用等待网页渲染,

否则,还需要等待,如果用time.sleep(),则有点笨拙,

#等待页面渲染完成
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
...
try:
    element = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, "loadedButton")))
# 等某个标签元素出来,不见鸭子不撒鹰。

finally:  # 撒鹰
    print(driver.find_element_by_id("content").text)
    driver.close()

或者用

try:
    elem == driver.find_element_by_tag_name("html")
    # 抛出StaleElementReferenceException异常说明elem元素已经消失了,也就说明页面已经跳转了。
except StaleElementReferenceException:  
    return

其他driver内置函数,可以通过查看源代码或者在pycharm提示获取。


4.Xpath定位Html标签

1.id定位:find_element_by_id(self, id_)
2.name定位:find_element_by_name(self, name)
3.class定位:find_element_by_class_name(self, name)
4.tag定位:find_element_by_tag_name(self, name)
5.link定位:find_element_by_link_text(self, link_text)
6.partial_link定位find_element_by_partial_link_text(self, link_text)
7.xpath定位:find_element_by_xpath(self, xpath)
8.css定位:find_element_by_css_selector(self, css_selector)
9.id复数定位find_elements_by_id(self, id_)
10.name复数定位find_elements_by_name(self, name)
11.class复数定位find_elements_by_class_name(self, name)
12.tag复数定位find_elements_by_tag_name(self, name)
13.link复数定位find_elements_by_link_text(self, text)
14.partial_link复数定位find_elements_by_partial_link_text(self, link_text)
15.xpath复数定位find_elements_by_xpath(self, xpath)
16.css复数定位find_elements_by_css_selector(self, css_selector
17.find_element(self, by='id', value=None)
18.find_elements(self, by='id', value=None)

其中element方法定位到是是单数,是直接定位到元素;elements方法是复数,这个学过英文的都知道,定位到的是一组元素,返回的是list队列。可参照Re函数中的findall理解。

如果定位不了标签,只能上JS大法:Selenium2+python自动化46-js解决click失效问题 - 上海-悠悠 - 博客园该作者已经出书,很便宜,可以考虑入一本。如果还想深入练习本节大法,同时推荐博客园ID:虫师虫师 - 博客园,这位兄台是做运维的,我最初就是用他的PDF教材入门Selenium,而且也已经出书了,是不是听这ID,就不是一般的牛逼,哈哈...


5.完整例子

这个例子属于标准化操作,在实际中可以适当简化,并结合上面的Xpath定位完成。

from selenium import webdriver
import time
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
 
dcap = dict(DesiredCapabilities.PHANTOMJS)
dcap["phantomjs.page.settings.userAgent"] = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36"

driver = webdriver.PhantomJS(executable_path=r'C:\Users\taojw\Desktop\pywork\phantomjs-2.1.1-windows\bin\phantomjs.exe', desired_capabilities=dcap)
driver.get("http://pythonscraping.com/pages/javascript/ajaxDemo.html")
time.sleep(3)
print(driver.find_element_by_id("content").text)
driver.close()

#设置PHANTOMJS的USER-AGENT
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
 
dcap = dict(DesiredCapabilities.PHANTOMJS)
dcap["phantomjs.page.settings.userAgent"] = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36"

 
driver = webdriver.PhantomJS(executable_path='./phantomjs.exe', desired_capabilities=dcap)
driver.get("http://dianping.com/")

cap_dict = driver.desired_capabilities  #查看所有可用的desired_capabilities属性。
for key in cap_dict:
    print('%s: %s' % (key, cap_dict[key]))
print(driver.current_url)
driver.quit()

#等待页面渲染完成
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

driver = webdriver.PhantomJS(executable_path=r'C:\Users\taojw\Desktop\pywork\phantomjs-2.1.1-windows\bin\phantomjs.exe')
driver.get("http://pythonscraping.com/pages/javascript/ajaxDemo.html")
try:
    element = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, "loadedButton")))
finally:
    print(driver.find_element_by_id("content").text)
    driver.close()

#处理Javascript重定向
from selenium import webdriver
import time
from selenium.webdriver.remote.webelement import WebElement
from selenium.common.exceptions import StaleElementReferenceException

def waitForLoad(driver):
    elem = driver.find_element_by_tag_name("html")
    count = 0
    while True:
        count += 1
        if count > 20:
            print("Timing out after 10 seconds and returning")
            return
        time.sleep(.5)
        try:
            elem == driver.find_element_by_tag_name("html")
        except StaleElementReferenceException:
            return

driver = webdriver.PhantomJS(executable_path=r'C:\Users\taojw\Desktop\pywork\phantomjs-2.1.1-windows\bin\phantomjs.exe')
driver.get("http://pythonscraping.com/pages/javascript/redirectDemo1.html")
waitForLoad(driver)
print(driver.page_source)
######
from selenium import webdriver
from selenium.webdriver.remote.webelement import WebElement
from selenium.webdriver import ActionChains

driver = webdriver.PhantomJS(executable_path='phantomjs/bin/phantomjs')
driver.get('http://pythonscraping.com/pages/javascript/draggableDemo.html')

print(driver.find_element_by_id("message").text)

element = driver.find_element_by_id("draggable")
target = driver.find_element_by_id("div2")
actions = ActionChains(driver)
actions.drag_and_drop(element, target).perform()

print(driver.find_element_by_id("message").text)
#######
#截屏
driver.get_screenshot_as_file('tmp/pythonscraping.png')

####
#登陆知乎,然后能自动点击页面下方的“更多”,以载入更多的内容
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver import ActionChains
import time
import sys

driver = webdriver.PhantomJS(executable_path='C:\Users\Gentlyguitar\Desktop\phantomjs-1.9.7-windows\phantomjs.exe')
driver.get("http://www.zhihu.com/#signin")
#driver.find_element_by_name('email').send_keys('your email')
driver.find_element_by_xpath('//input[@name="password"]').send_keys('your password')
#driver.find_element_by_xpath('//input[@name="password"]').send_keys(Keys.RETURN)
time.sleep(2)
driver.get_screenshot_as_file('show.png')
#driver.find_element_by_xpath('//button[@class="sign-button"]').click()
driver.find_element_by_xpath('//form[@class="zu-side-login-box"]').submit()

try:
    #等待页面加载完毕
    dr=WebDriverWait(driver,5)
    dr.until(lambda the_driver:the_driver.find_element_by_xpath('//a[@class="zu-top-nav-userinfo "]').is_displayed())
except:
    print('登录失败')
    sys.exit(0)
driver.get_screenshot_as_file('show.png')
#user=driver.find_element_by_class_name('zu-top-nav-userinfo ')
#webdriver.ActionChains(driver).move_to_element(user).perform() #移动鼠标到我的用户名
loadmore=driver.find_element_by_xpath('//a[@id="zh-load-more"]')
actions = ActionChains(driver)
actions.move_to_element(loadmore)
actions.click(loadmore)
actions.perform()
time.sleep(2)
driver.get_screenshot_as_file('show.png')
print(driver.current_url)
print(driver.page_source)
driver.quit()
##################################################################################

关于本节更多的实战技巧将会放在实例中。



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Python数据分析及可视化实例目录



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编辑于 2017-10-13

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