使用Python Selenium指定目录下载图片：登录网站后下载失败求助

我用Python的Selenium（配合undetected_chromedriver）尝试将图片下载到指定目录，代码在下载示例图片时正常，但登录目标网站后下载图片会提示“Error Failed to download”，不指定下载目录时则能正常下载。以下是我的代码：

import undetected_chromedriver as uc
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.action_chains import ActionChains
import pyautogui
from time import sleep

chrome_options = uc.ChromeOptions()
chrome_options.add_argument("--no-sandbox")
chrome_options.add_argument("--disable-dev-shm-usage")

# Specify the download directory
prefs = {
    "download.default_directory": "C:/Users/ExampleUser/Documents/ExampleFolder/",
    "download.prompt_for_download": False,
    "download.directory_upgrade": True,
    "safebrowsing.enabled": False
}
chrome_options.add_experimental_option("prefs", prefs)

# Create the webdriver instance with the modified options
driver = uc.Chrome(options=chrome_options)

#This is where I have used selenium to login to the website here
#havent posted the code to login

# Open the image page
driver.get('https://www.simplilearn.com/ice9/free_resources_article_thumb/what_is_image_Processing.jpg')
#This is just a random image, not the image on the website

sleep(3)

# Perform a right-click on the image
image_element = driver.find_element(By.XPATH, '/html/body/img')
sleep(3)
action_chains = ActionChains(driver)
action_chains.context_click(image_element).perform()
sleep(3)

# Press the "V" key to select the "Save Image As" option
pyautogui.press('v')

sleep(3)
# Press the Enter key to confirm the Save Image dialog
pyautogui.press('enter')

driver.quit()

问题原因 #

指定下载目录时，Chrome的安全策略或目标网站的下载限制（如防盗链、权限校验）会拦截下载请求；同时依赖pyautogui模拟右键保存的方式稳定性差，易受浏览器窗口状态影响。

解决方案一：直接通过HTTP请求下载（推荐） #

绕过Chrome下载对话框，利用登录后的Cookie直接请求图片资源并保存，不受浏览器设置限制，稳定性更高。

修改后的代码示例 #

import undetected_chromedriver as uc
from selenium.webdriver.common.by import By
import requests
import os
from time import sleep

chrome_options = uc.ChromeOptions()
chrome_options.add_argument("--no-sandbox")
chrome_options.add_argument("--disable-dev-shm-usage")

# 初始化浏览器并执行登录逻辑
driver = uc.Chrome(options=chrome_options)
# --- 插入你的网站登录代码 ---

# 打开目标图片页面
driver.get('https://www.your-target-website/image-url.jpg')
sleep(3)

# 获取图片URL和登录态Cookie
image_element = driver.find_element(By.XPATH, '/html/body/img')
image_url = image_element.get_attribute('src')
cookies = {cookie['name']: cookie['value'] for cookie in driver.get_cookies()}

# 指定保存目录并确保目录存在
save_dir = r"C:/Users/ExampleUser/Documents/ExampleFolder/"
os.makedirs(save_dir, exist_ok=True)
image_filename = image_url.split('/')[-1]
save_path = os.path.join(save_dir, image_filename)

# 下载并保存图片
response = requests.get(image_url, cookies=cookies, stream=True)
response.raise_for_status()
with open(save_path, 'wb') as f:
    for chunk in response.iter_content(chunk_size=8192):
        f.write(chunk)

driver.quit()

解决方案二：调整Chrome下载偏好设置 #

若坚持使用浏览器原生下载，可补充更多配置参数规避安全拦截：

修改后的偏好设置 #

prefs = {
    "download.default_directory": r"C:/Users/ExampleUser/Documents/ExampleFolder/",
    "download.prompt_for_download": False,
    "download.directory_upgrade": True,
    "safebrowsing.enabled": False,
    "profile.default_content_setting_values.automatic_downloads": 1,
    "download.extensions_to_open": "",
    "profile.content_settings.exceptions.automatic_downloads.*.setting": 1
}
chrome_options.add_experimental_option("prefs", prefs)

额外注意：

• 使用原始字符串（r"路径"）或双反斜杠避免路径转义错误
• 确保目标目录有写入权限（避开系统保护目录）
• 关闭浏览器安全浏览相关功能

内容的提问来源于stack exchange，提问作者John Smith