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Scrapy框架之Puppeteer渲染

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xiaotaomi
xiaotaomi 2017-11-30
悬赏:5飞吻


Puppeteer 是 Chrome 开发团队在 2017 年发布的一个 Node.js 包,用来模拟 Chrome 浏览器的运行。

为了爬取js渲染的html页面,我们需要用浏览器来解析js后生成html。在scrapy中可以利用pyppeteer来实现对应功能。

我们需要新建项目中middlewares.py文件(./项目名/middlewares.py)

KT1u-fysqfnf7273704.jpg

import websockets
from scrapy.http import HtmlResponse
from logging import getLogger
import asyncio
import pyppeteer
import logging
from concurrent.futures._base import TimeoutError
import base64
import sys
import random

pyppeteer_level = logging.WARNING
logging.getLogger('websockets.protocol').setLevel(pyppeteer_level)
logging.getLogger('pyppeteer').setLevel(pyppeteer_level)

PY3 = sys.version_info[0] >= 3


def base64ify(bytes_or_str):
    if PY3 and isinstance(bytes_or_str, str):
        input_bytes = bytes_or_str.encode('utf8')
    else:
        input_bytes = bytes_or_str

    output_bytes = base64.urlsafe_b64encode(input_bytes)
    if PY3:
        return output_bytes.decode('ascii')
    else:
        return output_bytes


class ProxyMiddleware(object):
    USER_AGENT = open('useragents.txt').readlines()

    def process_request(self, request, spider):
        # 代理服务器
        proxyHost = "t.16yun.cn"
        proxyPort = "31111"
        # 代理隧道验证信息
        proxyUser = "username"
        proxyPass = "password"

        request.meta['proxy'] = "http://{0}:{1}".format(proxyHost, proxyPort)

        # 添加验证头
        encoded_user_pass = base64ify(proxyUser + ":" + proxyPass)
        request.headers['Proxy-Authorization'] = 'Basic ' + encoded_user_pass

        # 设置IP切换头(根据需求)
        tunnel = random.randint(1, 10000)
        request.headers['Proxy-Tunnel'] = str(tunnel)
        request.headers['User-Agent'] = random.choice(self.USER_AGENT)


class PyppeteerMiddleware(object):
    def __init__(self, **args):
        """
        init logger, loop, browser
        :param args:
        """
        self.logger = getLogger(__name__)
        self.loop = asyncio.get_event_loop()
        self.browser = self.loop.run_until_complete(
            pyppeteer.launch(headless=True))
        self.args = args

    def __del__(self):
        """
        close loop
        :return:
        """
        self.loop.close()

    def render(self, url, retries=1, script=None, wait=0.3, scrolldown=False, sleep=0,
               timeout=8.0, keep_page=False):
        """
        render page with pyppeteer
        :param url: page url
        :param retries: max retry times
        :param script: js script to evaluate
        :param wait: number of seconds to wait before loading the page, preventing timeouts
        :param scrolldown: how many times to page down
        :param sleep: how many long to sleep after initial render
        :param timeout: the longest wait time, otherwise raise timeout error
        :param keep_page: keep page not to be closed, browser object needed
        :param browser: pyppetter browser object
        :param with_result: return with js evaluation result
        :return: content, [result]
        """

        # define async render
        async def async_render(url, script, scrolldown, sleep, wait, timeout, keep_page):
            try:
                # basic render
                page = await self.browser.newPage()
                await asyncio.sleep(wait)
                response = await page.goto(url, options={'timeout': int(timeout * 1000)})
                if response.status != 200:
                    return None, None, response.status
                result = None
                # evaluate with script
                if script:
                    result = await page.evaluate(script)

                # scroll down for {scrolldown} times
                if scrolldown:
                    for _ in range(scrolldown):
                        await page._keyboard.down('PageDown')
                        await asyncio.sleep(sleep)
                else:
                    await asyncio.sleep(sleep)
                if scrolldown:
                    await page._keyboard.up('PageDown')

                # get html of page
                content = await page.content()

                return content, result, response.status
            except TimeoutError:
                return None, None, 500
            finally:
                # if keep page, do not close it
                if not keep_page:
                    await page.close()

        content, result, status = [None] * 3

        # retry for {retries} times
        for i in range(retries):
            if not content:
                content, result, status = self.loop.run_until_complete(
                    async_render(url=url, script=script, sleep=sleep, wait=wait,
                                 scrolldown=scrolldown, timeout=timeout, keep_page=keep_page))
            else:
                break

        # if need to return js evaluation result
        return content, result, status

    def process_request(self, request, spider):
        """
        :param request: request object
        :param spider: spider object
        :return: HtmlResponse
        """
        if request.meta.get('render'):
            try:
                self.logger.debug('rendering %s', request.url)
                html, result, status = self.render(request.url)
                return HtmlResponse(url=request.url, body=html, request=request, encoding='utf-8',
                                    status=status)
            except websockets.exceptions.ConnectionClosed:
                pass

    @classmethod
    def from_crawler(cls, crawler):
        return cls(**crawler.settings.get('PYPPETEER_ARGS', {}))

然后修改项目配置文件 (./项目名/settings.py)

DOWNLOADER_MIDDLEWARES = {
        'scrapypyppeteer.middlewares.PyppeteerMiddleware': 543,
        'scrapypyppeteer.middlewares.ProxyMiddleware': 100,        
    }


 然后我们运行程序

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