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入门 - 库

安装

Pip

PyPI version

pip install --upgrade pip
pip install playwright
playwright install

Conda

Anaconda version

conda config --add channels conda-forge
conda config --add channels microsoft
conda install playwright
playwright install

这些命令会下载 Playwright 包并安装 Chromium、Firefox 和 WebKit 的浏览器二进制文件。要修改此行为,请参阅安装参数

用法

安装后,你可以在 Python 脚本中 import Playwright,并启动 3 种浏览器(chromiumfirefoxwebkit)中的任意一种。

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。如果你的现代项目使用 asyncio,则应使用异步 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 中截取屏幕截图。

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 在无头模式下运行浏览器。要查看浏览器 UI,请将 headless 选项设置为 False。你还可以使用 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)

你可以启动交互式 Python REPL

python

然后在其内部启动 Playwright 以进行快速实验

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

你可以将 Playwright 与 Pyinstaller 一起使用来创建独立的可执行文件。

main.py
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()

如果你想将浏览器与可执行文件捆绑在一起

PLAYWRIGHT_BROWSERS_PATH=0 playwright install chromium
pyinstaller -F main.py
注意

将浏览器与可执行文件捆绑会生成更大的二进制文件。建议只捆绑你使用的浏览器。

已知问题

time.sleep() 导致状态过时

你很可能不需要手动等待,因为 Playwright 具有自动等待功能。如果你仍然依赖手动等待,应该使用 page.wait_for_timeout(5000) 而不是 time.sleep(5),并且最好完全不等待超时,但有时它对于调试很有用。在这些情况下,请使用我们的等待方法 (wait_for_timeout) 而不是 time 模块。这是因为我们在内部依赖异步操作,使用 time.sleep(5) 时它们无法正确处理。

在 Windows 上与 asyncioSelectorEventLoop 不兼容

Playwright 在子进程中运行驱动程序,因此在 Windows 上需要 asyncioProactorEventLoop,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,因为它是 Python 3.8+ 的默认设置。

线程

Playwright 的 API 不是线程安全的。如果你在多线程环境中使用 Playwright,应该为每个线程创建一个 Playwright 实例。有关更多详细信息,请参阅线程问题