入门 - 库
安装
Pip
pip install --upgrade pip
pip install playwright
playwright install
Conda
conda config --add channels conda-forge
conda config --add channels microsoft
conda install playwright
playwright install
这些命令会下载 Playwright 包并为 Chromium、Firefox 和 WebKit 安装浏览器二进制文件。要修改此行为,请参阅安装参数。
用法
安装后,您可以在 Python 脚本中import
Playwright,并启动 3 种浏览器中的任何一种(chromium
、firefox
和webkit
)。
from playwright.sync_api import sync_playwright
with sync_playwright() as p:
browser = p.chromium.launch()
page = browser.new_page()
page.goto("https://playwright.net.cn")
print(page.title())
browser.close()
Playwright 支持两种 API 变体:同步和异步。如果您的现代项目使用 asyncio,您应该使用异步 API。
import asyncio
from playwright.async_api import async_playwright
async def main():
async with async_playwright() as p:
browser = await p.chromium.launch()
page = await browser.new_page()
await page.goto("https://playwright.net.cn")
print(await page.title())
await browser.close()
asyncio.run(main())
第一个脚本
在我们的第一个脚本中,我们将导航到https://playwright.net.cn/
并在 WebKit 中进行截图。
from playwright.sync_api import sync_playwright
with sync_playwright() as p:
browser = p.webkit.launch()
page = browser.new_page()
page.goto("https://playwright.net.cn/")
page.screenshot(path="example.png")
browser.close()
默认情况下,Playwright 以无头模式运行浏览器。要查看浏览器 UI,请将headless选项设置为False
。您还可以使用slow_mo来减慢执行速度。在调试工具部分了解更多信息。
firefox.launch(headless=False, slow_mo=50)
交互模式 (REPL)
您可以启动交互式 python REPL
python
然后在其中启动 Playwright 进行快速实验
from playwright.sync_api import sync_playwright
playwright = sync_playwright().start()
# Use playwright.chromium, playwright.firefox or playwright.webkit
# Pass headless=False to launch() to see the browser UI
browser = playwright.chromium.launch()
page = browser.new_page()
page.goto("https://playwright.net.cn/")
page.screenshot(path="example.png")
browser.close()
playwright.stop()
异步 REPL,例如asyncio
REPL
python -m asyncio
from playwright.async_api import async_playwright
playwright = await async_playwright().start()
browser = await playwright.chromium.launch()
page = await browser.new_page()
await page.goto("https://playwright.net.cn/")
await page.screenshot(path="example.png")
await browser.close()
await playwright.stop()
Pyinstaller
您可以将 Playwright 与 Pyinstaller 一起使用来创建独立的可执行文件。
from playwright.sync_api import sync_playwright
with sync_playwright() as p:
browser = p.chromium.launch()
page = browser.new_page()
page.goto("https://playwright.net.cn/")
page.screenshot(path="example.png")
browser.close()
如果您想将浏览器与可执行文件捆绑在一起
- Bash
- PowerShell
- 批处理
PLAYWRIGHT_BROWSERS_PATH=0 playwright install chromium
pyinstaller -F main.py
$env:PLAYWRIGHT_BROWSERS_PATH="0"
playwright install chromium
pyinstaller -F main.py
set PLAYWRIGHT_BROWSERS_PATH=0
playwright install chromium
pyinstaller -F main.py
将浏览器与可执行文件捆绑在一起会生成更大的二进制文件。建议只捆绑您使用的浏览器。
已知问题
time.sleep()
导致状态过时
您很可能不需要手动等待,因为 Playwright 具有自动等待功能。如果您仍然依赖它,您应该使用page.wait_for_timeout(5000)
而不是time.sleep(5)
,并且最好根本不等待超时,但有时这对于调试很有用。在这些情况下,请使用我们的等待(wait_for_timeout
)方法而不是time
模块。这是因为我们在内部依赖于异步操作,当使用time.sleep(5)
时,它们无法正确处理。
在 Windows 上与 asyncio
的 SelectorEventLoop
不兼容
Playwright 在子进程中运行驱动程序,因此它在 Windows 上需要 asyncio
的 ProactorEventLoop
,因为 SelectorEventLoop
不支持异步子进程。
在 Windows Python 3.7 上,Playwright 将默认事件循环设置为 ProactorEventLoop
,因为它在 Python 3.8+ 中是默认的。
多线程
Playwright 的 API 不是线程安全的。如果您在多线程环境中使用 Playwright,则应该为每个线程创建一个 Playwright 实例。有关详细信息,请参阅线程问题。