前言
本节学习selenium
得说一句这节课程讲的不行
很多讲明白
就先记一笔
准备后续自己再看看
可参考的几篇
官方文档
针对python的文档
详解
1、简介
浏览器的工作原理
网页三元素
- html负责内容
- css负责样式
- JavaScript负责动作
从数据的角度考虑，网页上呈现出来的数据的来源：
- html文件
- ajax接口
- javascript加载
可参考
原理详解
Selenium
诞生于2014年，创造者是ThoughtWorks公司的测试工程师Jason Huggins
目的就是做自动化测试，用以检测网页交互，避免重复劳动。
这个工具可以用来自动加载网页，供爬虫抓取数据。
支持哪些浏览器和系统：
- Google Chrome
- Internet Explorer 7, 8, 9, 10, and 11 on appropriate combinations of Vista, Windows 7, Windows 8, and Windows 8.1.
- Firefox
- Safari
- Opera
- phantomjs（一款无头浏览器，已停止维护）
- Android (with Selendroid or appium)
- IOS (with ios-driver or appium)
2、安装与使用
# 安装selenium:
pip install selenium
# 引入webdriver：
from selenium import webdriver
# 设置选项：
option = webdriver.ChromeOptions()
option.add_argument('headless')
# 添加驱动
driver = webdriver.Chrome('./chromedriver',chrome_options=option)3、页面交互
# 查找元素：
element = driver.find_element_by_id("passwd-id")
element = driver.find_element_by_name("passwd")
element = driver.find_element_by_xpath("//input[@id='passwd-id']")
# 输入文字：
element.send_keys("some text")
# 点击
element.click()
# 动作链
from selenium.webdriver import ActionChains
action_chains = ActionChains(driver)
action_chains.drag_and_drop(element, target).perform()
# 在页面间切换
window_handles = driver.window_handles
driver.switch_to.window(window_handles[-1])
# 保存网页截图
driver.save_screenshot('screen.png')4、定位元素
# 查找一个元素
find_element_by_id
find_element_by_name
find_element_by_xpath
find_element_by_link_text
find_element_by_partial_link_text
find_element_by_tag_name
find_element_by_class_name
find_element_by_css_selector
# 查找多个元素
find_elements_by_name
find_elements_by_xpath
find_elements_by_link_text
find_elements_by_partial_link_text
find_elements_by_tag_name
find_elements_by_class_name
find_elements_by_css_selector
# 通过id定位
<html>
<body>
<form id="loginForm">
<input name="username" type="text" />
<input name="password" type="password" />
<input name="continue" type="submit" value="Login" />
</form>
</body>
<html>
login_form = driver.find_element_by_id('loginForm')
# 通过name定位
<html>
<body>
<form id="loginForm">
<input name="username" type="text" />
<input name="password" type="password" />
<input name="continue" type="submit" value="Login" />
<input name="continue" type="button" value="Clear" />
</form>
</body>
<html>
username = driver.find_element_by_name('username')
password = driver.find_element_by_name('password')
# 通过链接文本定位
<html>
<body>
<p>Are you sure you want to do this?</p>
<a href="continue.html">Continue</a>
<a href="cancel.html">Cancel</a>
</body>
<html>
continue_link = driver.find_element_by_link_text('Continue')
continue_link = driver.find_element_by_partial_link_text('Conti')
# 通过标签名定位
<html>
<body>
<h1>Welcome</h1>
<p>Site content goes here.</p>
</body>
<html>
heading1 = driver.find_element_by_tag_name('h1')
# 通过类名定位
<html>
<body>
<p class="content">Site content goes here.</p>
</body>
<html>
content = driver.find_element_by_class_name('content')
# 通过CSS选择器定位
<html>
<body>
<p class="content">Site content goes here.</p>
</body>
<html>
content = driver.find_element_by_css_selector('p.content')
# 两个私有方法
from selenium.webdriver.common.by import By
driver.find_element(By.XPATH, '//button[text()="Some text"]')
driver.find_elements(By.XPATH, '//button')
# By后面可以用来定位的属性
ID = "id"
XPATH = "xpath"
LINK_TEXT = "link text"
PARTIAL_LINK_TEXT = "partial link text"
NAME = "name"
TAG_NAME = "tag name"
CLASS_NAME = "class name"
CSS_SELECTOR = "css selector"
# 推荐使用xpath定位
username = driver.find_element_by_xpath("//form[input/@name='username']")
username = driver.find_element_by_xpath("//form[@id='loginForm']/input[1]")
username = driver.find_element_by_xpath("//input[@name='username']")
# 推荐使用链接文本定位
continue_link = driver.find_element_by_link_text('Continue')
continue_link = driver.find_element_by_partial_link_text('Conti')5、等待
# 等待
from selenium import webdriver
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.Firefox()
driver.get("http://somedomain/url_that_delays_loading")
try:
element = WebDriverWait(driver, 10).until(
EC.presence_of_element_located((By.ID, "myDynamicElement"))
)
finally:
driver.quit()
# 条件
title_is
title_contains
presence_of_element_located
visibility_of_element_located
visibility_of
presence_of_all_elements_located
text_to_be_present_in_element
text_to_be_present_in_element_value
frame_to_be_available_and_switch_to_it
invisibility_of_element_located
element_to_be_clickable
staleness_of
element_to_be_selected
element_located_to_be_selected
element_selection_state_to_be
element_located_selection_state_to_be
alert_is_present6、例子
与百度的交互
from selenium import webdriver
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
option = webdriver.ChromeOptions()
option.add_argument('headless')
# 要换成适应自己操作系统的chromedriver
driver = webdriver.Chrome(
executable_path='/Users/seancheney/Documents/kkb_python/headless/chromedriver', #绝对路径
chrome_options=option #上面设置的option
)
url = 'https://www.baidu.com'
# 打开网站
driver.get(url)
# 打印当前页面标题
print(driver.title)
# 在搜索框中输入文字
timeout = 5
search_content = WebDriverWait(driver, timeout).until(
# lambda d: d.find_element_by_xpath('//input[@id="kw"]')
EC.presence_of_element_located((By.XPATH, '//input[@id="kw"]'))
)
search_content.send_keys('python')
# 等待页面
import time
time.sleep(3)
# 模拟点击“百度一下”
search_button = WebDriverWait(driver, timeout).until(
lambda d: d.find_element_by_xpath('//input[@id="su"]'))
search_button.click()
# 打印搜索结果
search_results = WebDriverWait(driver, timeout).until(
# lambda d: d.find_elements_by_xpath('//h3[@class="t c-title-en"] | //h3[@class="t"]')
lambda e: e.find_elements_by_xpath('//h3[contains(@class,"t")]/a[1]')
)
print(search_results)
for item in search_results:
print(item.text)
driver.close()抓取头条新闻
from selenium import webdriver
from selenium.webdriver.support.wait import WebDriverWait
option = webdriver.ChromeOptions()
driver = webdriver.Chrome(
executable_path='/Users/seancheney/Documents/kkb_python/headless/chromedriver',
chrome_options=option
)
# 今日头条
url = 'https://www.toutiao.com'
driver.get(url)
print(driver.page_source)
timeout = 5
coin_links = WebDriverWait(driver, timeout).until(
lambda d: d.find_elements_by_xpath('//div[@ga_event="article_title_click"]/a')
)
for item in coin_links:
print(item.text)
print(item.get_attribute('href'))结语
selenium这个自动化工具确实好用
笔者准备后续多看看官方文档