[Day21] Python 爬蟲-2

2024 iThome 鐵人賽

DAY 21

自我挑戰組

從零開始學Python系列第 21 篇

16th鐵人賽

pochama

2024-09-11 17:28:46

202 瀏覽

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續上一篇，用以下code可以自動開啟瀏覽器，並在搜尋欄中輸入「iphone 16」，並按下enter。

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
import time
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys

chrome_driver_path = "/Users/shiyongchun/Desktop/HTML_CSS/chromedriver/chromedriver"  
service = Service(chrome_driver_path)
driver = webdriver.Chrome(service=service)
driver.get("https://google.com")
search = driver.find_element(By.NAME, "q")
search.send_keys("iphone 16")
search.send_keys(Keys.RETURN)
print(driver.title)

time.sleep(10)
driver.quit()

在搜尋關鍵字後，擷取標題

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
import time
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys

chrome_driver_path = "/Users/shiyongchun/Desktop/HTML_CSS/chromedriver/chromedriver"  
service = Service(chrome_driver_path)
driver = webdriver.Chrome(service=service)
driver.get("https://google.com")
search = driver.find_element(By.NAME, "q")
search.send_keys("iphone 16")
search.send_keys(Keys.RETURN)
print(driver.title)

titles = driver.find_elements(By.CLASS_NAME, "LC20lb")
for title in titles:
    print(title.text)

time.sleep(10)
driver.quit()

其中titles = driver.find_elements(By.CLASS_NAME, "LC20lb")，可以在網頁程式碼中搜尋到，檢視原始碼的快捷鍵在Mac 是：⌘ + Option + U，windows電腦為F12。

以下為google搜尋「iphone16」後，擷取得標題。

網頁搜尋時間
上述的例子中，並沒有出現這個問題，若有時候網頁搜尋跑出資料的速度較慢，會導致網頁還沒有出現結果就執行下一個擷取標題的動作，因此需要一個explicit wait來等待網頁搜尋的動作執行完畢。

更多資料可以參考：explicit wait

from selenium.webdriver.common.by import By
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

這三行code執行後，就可以不用在前面加上time.sleep()

chrome_driver_path = "/Users/shiyongchun/Desktop/HTML_CSS/chromedriver/chromedriver"  
service = Service(chrome_driver_path)
driver = webdriver.Chrome(service=service)
driver.get("https://google.com")
search = driver.find_element(By.NAME, "q")
search.send_keys("iphone 16")
search.send_keys(Keys.RETURN)

time.sleep(2) #這行可以不用加了
titles = driver.find_elements(By.CLASS_NAME, "LC20lb")
for title in titles:
    print(title.text)

但改由以下程式碼來運行：等到頁面出現某個標籤之後才會開始擷取資料。

WebDriverWait(driver, 20).until(
    EC.presence_of_element_located((By.CLASS_NAME, "logo"))
)

會等待google的logo出現，最多20秒。

以下為完整程式碼：

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
import time
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

chrome_driver_path = "/Users/shiyongchun/Desktop/HTML_CSS/chromedriver/chromedriver"  
service = Service(chrome_driver_path)
driver = webdriver.Chrome(service=service)
driver.get("https://google.com")
search = driver.find_element(By.NAME, "q")
search.send_keys("iphone 16")
search.send_keys(Keys.RETURN)
print(driver.title)

WebDriverWait(driver, 20).until(
    EC.presence_of_element_located((By.CLASS_NAME, "logo"))
)

titles = driver.find_elements(By.CLASS_NAME, "LC20lb")
for title in titles:
    print(title.text)

time.sleep(10)
driver.quit()

網頁操作

點擊連結：

link = driver.find_element_by_link_text("放入想要點擊的網頁名稱")
link.click()

driver.back()

driver.forward()

將搜尋欄位清空：可以避免關鍵字錯誤

search.clear()

爬取google關鍵字圖片

WebDriverWait(driver, 10).until(
    EC.presence_of_element_located((By.LINK_TEXT, "圖片"))
).click()

此行程式碼會在google搜尋之後，點下圖片的選項

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
import time
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC


chrome_driver_path = "/Users/shiyongchun/Desktop/HTML_CSS/chromedriver/chromedriver"  
service = Service(chrome_driver_path)
driver = webdriver.Chrome(service=service)
driver.get("https://google.com")
search = driver.find_element(By.NAME, "q")
search.send_keys("iphone 16")
search.send_keys(Keys.RETURN)

WebDriverWait(driver, 10).until(
    EC.presence_of_element_located((By.LINK_TEXT, "圖片"))
).click()

time.sleep(10)
driver.quit()

接下來可以根據class來下載圖片

可以發現圖片的class為「YQ4gaf」，src為網址

WebDriverWait(driver, 10).until(
    EC.presence_of_element_located((By.CLASS_NAME, "YQ4gaf"))
)

imgs = driver.find_elements(By.CLASS_NAME, "YQ4gaf")
for img in imgs:
    print(img.get_attribute("src"))

以上程式碼可以print出來所有圖片的url