Selenium 模拟浏览器动态加载页面的实现方法

相信爬取大公司的数据时，常常会遇到页面信息动态加载的问题，

如果仅仅使用content = urllib2.urlopen(URL).read()，估计信息是获取不全的，这时候就需要模拟浏览器加载页面的过程，

selenium提供了方便的方法，我也是菜鸟，试了很多种方式，下面提供觉得最靠谱的（已经证明对于爬取新浪微博的topic、twitter under topic完全没问题）。

至于下面的browser变量是什么，看前面的几篇文章。

首先是请求对应的URL：

right_URL = URL.split("from")[0] + "current_page="+str(current_page) + "&since_id="+str(since_id) + "&page="+str(page_index) + "#Pl_Third_App__"+str(Pl_Third_App) 
print right_URL 
try: 
browser.get(right_URL) 
print "loading more, sleep 3 seconds ... 0" 
time.sleep(3) # NO need for this sleep, but we add ... 
browser = selenuim_loading_more(browser, method_index=0) 
except: 
print "one exception happen ==> get_tweeter_under_topic 2 ..." 
pass

然后模拟浏览器，加载更多（推荐使用method_index=0，已经证明比其他好用很多）：

def selenuim_loading_more(browser, method_index=0): 
  if method_index==0: 
    browser.implicitly_wait(3) # 为了快速滑动，先设置超时时间为1秒 
    # while True: 
    for i in range(1, 4): # at most 3 times 
      print "loading more, window.scrollTo bettom for the", i,"time ..." 
      browser.execute_script("window.scrollTo(0,document.body.scrollHeight);") 
      try: 
        # 定位页面底部的换页tab 
        browser.find_element_by_css_selector("div[class='W_pages']") 
        break # 如果没抛出异常就说明找到了底部标志，跳出循环 
      except NoSuchElementException: 
        pass # 抛出异常说明没找到底部标志，继续向下滑动 
    browser.implicitly_wait(4) # 将超时时间改回10秒 
  elif method_index==1: 
    browser.find_element_by_css_selector("div[class='empty_con clearfix']").click() # loading more 
    print "loading more, sleep 4 seconds ... 1" 
    time.sleep(4) 
    browser.find_element_by_css_selector("div[class='empty_con clearfix']").click() # loading more 
    print "loading more, sleep 3 seconds ... 2" 
    time.sleep(2) 
  elif method_index==2: 
    load_more_1 = browser.find_element_by_css_selector("div[class='empty_con clearfix']") # loading more         
    ActionChains(browser).click(load_more_1).perform() 
    print "loading more, sleep 4 seconds ... 1" 
    time.sleep(4) 
    load_more_2 = browser.find_element_by_css_selector("div[class='empty_con clearfix']") # loading more         
    ActionChains(browser).click(load_more_2).perform() 
    print "loading more, sleep 3 seconds ... 2" 
    time.sleep(2) 
  elif method_index==3: 
    print "loading more, sleep 4 seconds ... 1" 
    element = WebDriverWait(browser, 4).until( 
      EC.element_to_be_clickable((By.CSS_SELECTOR, "div[class='empty_con clearfix']")) 
    ) 
    element.click() 
    print "loading more, sleep 2 seconds ... 2" 
    WebDriverWait(browser, 2).until( 
      EC.element_to_be_clickable((By.CSS_SELECTOR, "div[class='empty_con clearfix']")) 
    ).click() 
  return browser