webdriver(处理select下拉框元素)

 """处理下拉框"""

 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 ES
 from selenium.webdriver.common.action_chains import ActionChains
 from selenium.webdriver.support.select import Select
 import time

 def elementFind(driver, way, str):
     """
     封装具有等待时间加判断的定位方法
     :param driver:
     :param way: 定位方式
     :param str: 要定位的元素
     :return:
     """
     try:
         element = WebDriverWait(driver, 5, 0.5).until(ES.presence_of_element_located((way, str)))
         return element
     except:
         return False

 driver = webdriver.Chrome()
 driver.get("http://www.baidu.com")

 el = elementFind(driver, By.LINK_TEXT, '设置')
 ActionChains(driver).move_to_element(el).perform()

 time.sleep(1)
 driver.find_element(By.CSS_SELECTOR, '.setpref').click()

 """
 1 select_by_index          # 通过索引定位
 2 select_by_value          # 通过value值定位
 3 select_by_visible_text   # 通过文本值定位
 """
 time.sleep(1)
 s = driver.find_element_by_css_selector("#nr")
 Select(s).select_by_value('')

 # 二次定位方式
 time.sleep(1)
 driver.find_element_by_id("nr").find_element_by_xpath("//option[@value='20']").click()

 time.sleep(3)
 driver.quit()