Python爬虫 selenium

库的安装

pip3 install selenium

声明浏览器对象

from selenium import webdriver

browser = webdriver.chrome()
browser = webdriver.firefox()
browser = webdriver.edge()
browser = webdriver.phantomjs()
browser = webdriver.safari()

访问页面

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
print(browser.page_source)
browser.close()

查找元素

查找单个元素的 element

* 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

查找多个元素的 elements

* 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

单个元素

第一种方式直接指定通过某种方式查找 find_element_by...

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
input_first = browser.find_element_by_id('q')
input_second = browser.find_element_by_css_selector('#q')
input_third = browser.find_element_by_xpath('//*[@id="q"]')
print(input_first, input_second, input_third)
browser.close()

第二种方式 通过 find_element(by.xx , ' ....')

from selenium import webdriver
from selenium.webdriver.common.by import by

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
input_first = browser.find_element(by.id, 'q')
print(input_first)
browser.close()
"""
<selenium.webdriver.remote.webelement.webelement (session="1f209c0d11551c40d9d20ad964fef244", element="0.07914603542731591-1")>
"""

多个元素

第一种

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
lis = browser.find_elements_by_css_selector('.service-bd li')
print(lis)
browser.close()

打印的结果如下

print(lis)
browser.close()
[<selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-1")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-2")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-3")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-4")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-5")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-6")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-7")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-8")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-9")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-10")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-11")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-12")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-13")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-14")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-15")>, <selenium.webdriver.remote.webelement.webelement (session="c26290835d4457ebf7d96bfab3740d19", element="0.09221044033125603-16")>]

view code

第二种

from selenium import webdriver
from selenium.webdriver.common.by import by

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
lis = browser.find_elements(by.css_selector, '.service-bd li')
print(lis)
browser.close()

元素交互操作

以下操作往淘宝输入框中输入 iphone 然后清空再输入 ipad 在点击搜索

from selenium import webdriver
import time

browser = webdriver.chrome()
browser.get('https://www.taobao.com')
input = browser.find_element_by_id('q')
input.send_keys('iphone')
time.sleep(1)
input.clear()
input.send_keys('ipad')
button = browser.find_element_by_class_name('btn-search')
button.click()

可了解更多可以查看: 

交互动作

from selenium import webdriver
from selenium.webdriver import actionchains

browser = webdriver.chrome()
url = 'http://www.runoob.com/try/try.php?filename=jqueryui-api-droppable'
browser.get(url)
browser.switch_to.frame('iframeresult') # 选择iframe
source = browser.find_element_by_css_selector('#draggable')
target = browser.find_element_by_css_selector('#droppable')
actions = actionchains(browser) # 动作链
actions.drag_and_drop(source, target)
actions.perform()

更多操作: 

执行javascript

通过函数 execute_script()

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.zhihu.com/explore')
browser.execute_script('window.scrollto(0, document.body.scrollheight)')
browser.execute_script('alert("to bottom")')

获取元素信息

1.获取属性 get_attribute()

from selenium import webdriver
from selenium.webdriver import actionchains

browser = webdriver.chrome()
url = 'https://www.zhihu.com/explore'
browser.get(url)
logo = browser.find_element_by_id('zh-top-link-logo')
print(logo)
print(logo.get_attribute('class'))
"""
<selenium.webdriver.remote.webelement.webelement (session="e08c0f28d7f44d75ccd50df6bb676104", element="0.7236390660048155-1")>
zu-top-link-logo
"""

2.获取文本值 text

from selenium import webdriver

browser = webdriver.chrome()
url = 'https://www.zhihu.com/explore'
browser.get(url)
input = browser.find_element_by_class_name('zu-top-add-question')
print(input.text)

打印结果: 

提问

获取id、位置、标签名、大小等

from selenium import webdriver

browser = webdriver.chrome()
url = 'https://www.zhihu.com/explore'
browser.get(url)
input = browser.find_element_by_class_name('zu-top-add-question')
print(input.id)
print(input.location)
print(input.tag_name)
print(input.size)

"""
0.6822924344980397-1
{'y': 7, 'x': 774}
button
{'height': 32, 'width': 66}
"""

frame 

切换 子iframe switch_to.frame("iframe的id值")

切换回来 switch_to.parent_frame()

import time
from selenium import webdriver
from selenium.common.exceptions import nosuchelementexception

browser = webdriver.chrome()
url = 'http://www.runoob.com/try/try.php?filename=jqueryui-api-droppable'
browser.get(url)
browser.switch_to.frame('iframeresult')
source = browser.find_element_by_css_selector('#draggable')
print(source)
try:
    logo = browser.find_element_by_class_name('logo')
except nosuchelementexception:
    print('no logo')
browser.switch_to.parent_frame()
logo = browser.find_element_by_class_name('logo')
print(logo)
print(logo.text)

"""
<selenium.webdriver.remote.webelement.webelement (session="4bb8ac03ced4ecbdefef03ffdc0e4ccd", element="0.44746093888932004-1")>
no logo
<selenium.webdriver.remote.webelement.webelement (session="4bb8ac03ced4ecbdefef03ffdc0e4ccd", element="0.13792611320464965-2")>
runoob.com
"""

等待

由于页面需要时间刷新，防止某些元素未刷新出来就访问导致出错，可设置等待时间

隐式等待

当使用了隐式等待执行测试的时候，如果 webdriver没有在 dom中找到元素，将继续等待，超出设定时间后则抛出找不到元素的异常, 换句话说，当查找元素或元素并没有立即出现的时候，隐式等待将等待一段时间再查找 dom，默认的时间是0

from selenium import webdriver

browser = webdriver.chrome()
browser.implicitly_wait(10) # 等待时间
browser.get('https://www.zhihu.com/explore')
input = browser.find_element_by_class_name('zu-top-add-question')
print(input)

打印结果:

<selenium.webdriver.remote.webelement.webelement (session="b29214772d59e912f1ac52e96ed29abe", element="0.12886805191194894-1")>

显示等待

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

browser = webdriver.chrome()
browser.get('https://www.taobao.com/')
wait = webdriverwait(browser, 10) # 最长的等待时间
input = wait.until(ec.presence_of_element_located((by.id, 'q')))
button = wait.until(ec.element_to_be_clickable((by.css_selector, '.btn-search')))
print(input, button)

打印结果:

<selenium.webdriver.remote.webelement.webelement (session="07dd2fbc2d5b1ce40e82b9754aba8fa8", element="0.5642646294074107-1")> <selenium.webdriver.remote.webelement.webelement (session="07dd2fbc2d5b1ce40e82b9754aba8fa8", element="0.5642646294074107-2")>

元素动作判断

title_is 标题是某内容
title_contains 标题包含某内容
presence_of_element_located 元素加载出，传入定位元组，如(by.id, 'p')
visibility_of_element_located 元素可见，传入定位元组
visibility_of 可见，传入元素对象
presence_of_all_elements_located 所有元素加载出
text_to_be_present_in_element 某个元素文本包含某文字
text_to_be_present_in_element_value 某个元素值包含某文字
frame_to_be_available_and_switch_to_it frame加载并切换
invisibility_of_element_located 元素不可见
element_to_be_clickable 元素可点击
staleness_of 判断一个元素是否仍在dom，可判断页面是否已经刷新
element_to_be_selected 元素可选择，传元素对象
element_located_to_be_selected 元素可选择，传入定位元组
element_selection_state_to_be 传入元素对象以及状态，相等返回true，否则返回false
element_located_selection_state_to_be 传入定位元组以及状态，相等返回true，否则返回false
alert_is_present 是否出现alert

详细内容：

前进与后退 

与浏览器的交互 back() 后退   froward() 前进

import time
from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.baidu.com/')
browser.get('https://www.taobao.com/')
browser.get('https://www.python.org/')
browser.back()
time.sleep(1)
browser.forward()
browser.close()

获取cookies 以及添加cookies

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.zhihu.com/explore')
print(browser.get_cookies())
browser.add_cookie({'name': 'name', 'domain': 'www.zhihu.com', 'value': 'germey'})
print(browser.get_cookies())
browser.delete_all_cookies()
print(browser.get_cookies())

打印结果:

[{'secure': false, 'value': '"ngm0ztm5ndawmweyndqwndk5odlkzwy3otkxy2i0ndy=|1491604091|236e34290a6f407bfbb517888849ea509ac366d0"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'l_cap_id', 'expiry': 1494196091.403418}, {'secure': false, 'value': '"yweyogy4mmi1mzq2ngy5mmfimjgzzguzzwjjytgwyjy=|1491604091|ff946847ddb5881245bdb7a5e6401b70dc61013f"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'cap_id', 'expiry': 1494196091.402855}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'l_n_c'}, {'secure': false, 'value': '"mjcxmde3yzu1yji4ndljzjljntq4zdiyowjjztbhnmy=|1491604091|8da4722b56a1545c2020dba97394a220c0eca8d9"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'r_cap_id', 'expiry': 1494196091.402525}, {'secure': false, 'value': '51854390', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmc'}, {'secure': false, 'value': '"aadco7e1kguptqveomieruzwka7zubhv-vy=|1491604091"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'd_c0', 'expiry': 1586212091.344773}, {'secure': false, 'value': '51854390.1491604091.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmz', 'expiry': 1507372091}, {'secure': false, 'value': '3cc99fc5-8706-43fc-90ac-3ad991bd1a25', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '_zap', 'expiry': 1554676091}, {'secure': false, 'value': '97cb00128ccb46659728f7c69cc191b0|1491604091000|1491604091000', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'q_c1', 'expiry': 1586212091.401644}, {'secure': false, 'value': '51854390.2.10.1491604091', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmb', 'expiry': 1491605891}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'n_c'}, {'secure': false, 'value': '51854390.000--|3=entry_date=20170408=1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmv', 'expiry': 1554676091}, {'secure': false, 'value': '51854390.669300758.1491604091.1491604091.1491604091.1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utma', 'expiry': 1554676091}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmt', 'expiry': 1491604691}, {'secure': false, 'value': 'aqaaalczuwh+dgiaeu3ppha+csdpnxvt', 'domain': 'www.zhihu.com', 'path': '/', 'httponly': true, 'name': 'aliyungf_tc'}]
[{'secure': false, 'value': 'germey', 'domain': '.www.zhihu.com', 'path': '/', 'httponly': false, 'name': 'name'}, {'secure': false, 'value': '"ngm0ztm5ndawmweyndqwndk5odlkzwy3otkxy2i0ndy=|1491604091|236e34290a6f407bfbb517888849ea509ac366d0"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'l_cap_id', 'expiry': 1494196091.403418}, {'secure': false, 'value': '"yweyogy4mmi1mzq2ngy5mmfimjgzzguzzwjjytgwyjy=|1491604091|ff946847ddb5881245bdb7a5e6401b70dc61013f"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'cap_id', 'expiry': 1494196091.402855}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'l_n_c'}, {'secure': false, 'value': '"mjcxmde3yzu1yji4ndljzjljntq4zdiyowjjztbhnmy=|1491604091|8da4722b56a1545c2020dba97394a220c0eca8d9"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'r_cap_id', 'expiry': 1494196091.402525}, {'secure': false, 'value': '51854390', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmc'}, {'secure': false, 'value': '"aadco7e1kguptqveomieruzwka7zubhv-vy=|1491604091"', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'd_c0', 'expiry': 1586212091.344773}, {'secure': false, 'value': '51854390.1491604091.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmz', 'expiry': 1507372091}, {'secure': false, 'value': '3cc99fc5-8706-43fc-90ac-3ad991bd1a25', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '_zap', 'expiry': 1554676091}, {'secure': false, 'value': '97cb00128ccb46659728f7c69cc191b0|1491604091000|1491604091000', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'q_c1', 'expiry': 1586212091.401644}, {'secure': false, 'value': '51854390.2.10.1491604091', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmb', 'expiry': 1491605891}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': 'n_c'}, {'secure': false, 'value': '51854390.000--|3=entry_date=20170408=1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmv', 'expiry': 1554676091}, {'secure': false, 'value': '51854390.669300758.1491604091.1491604091.1491604091.1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utma', 'expiry': 1554676091}, {'secure': false, 'value': '1', 'domain': '.zhihu.com', 'path': '/', 'httponly': false, 'name': '__utmt', 'expiry': 1491604691}, {'secure': false, 'value': 'aqaaalczuwh+dgiaeu3ppha+csdpnxvt', 'domain': 'www.zhihu.com', 'path': '/', 'httponly': true, 'name': 'aliyungf_tc'}]
[]

view code

浏览器选项卡的管理

通过switch_to_window(browser.window_handles[])

import time
from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.baidu.com')
browser.execute_script('window.open()')
print(browser.window_handles)
browser.switch_to_window(browser.window_handles[1])
browser.get('https://www.taobao.com')
time.sleep(1)
browser.switch_to_window(browser.window_handles[0])
browser.get('https://python.org')

打印结果:

['cdwindow-4f58e3a7-7167-4587-bedf-9cd8c867f435', 'cdwindow-6e05f076-6d77-453a-a36c-32baacc447df']

异常处理

比如下面的元素不存在的处理 打印肯定会报错的啦

from selenium import webdriver

browser = webdriver.chrome()
browser.get('https://www.baidu.com')
browser.find_element_by_id('hello')

处理方式:

from selenium import webdriver
from selenium.common.exceptions import timeoutexception, nosuchelementexception

browser = webdriver.chrome()
try:
    browser.get('https://www.baidu.com')
except timeoutexception:
    print('time out')
try:
    browser.find_element_by_id('hello')
except nosuchelementexception:
    print('no element')
finally:
    browser.close()

打印结果:

no element

详细文档：