无法让 Scrapy 解析并遵循 301、302 重定向

我正在尝试编写一个非常简单的网站爬虫来列出 URL 以及 200、301、302 和 404 http 状态代码的引用和状态代码。

事实证明，Scrapy 工作得很好，我的脚本正确地使用它来抓取网站，并且可以毫无问题地列出状态代码为 200 和 404 的 url。

问题是：我找不到如何让 scrapy 遵循重定向并解析/输出它们。我可以让其中一个工作，但不能让两个都工作。

到目前为止我尝试过的：

• setting meta={'dont_redirect':True}和设置REDIRECTS_ENABLED = False

• 将301、302添加到handle_httpstatus_list

• 更改重定向中间件文档中指定的设置

• 阅读重定向中间件代码以获得洞察

• 上述所有内容的各种组合

• 其他随机的东西

这是公共回购 https://gitlab.savoirfairelinux.com/fpotvin/easy-scrapy/tree/master如果你想看一下代码。

如果您想解析 301 和 302 响应，并同时跟踪它们，请要求您的回调处理 301 和 302 并模仿 RedirectMiddleware 的行为。

测试1（不工作）

让我们从一个简单的蜘蛛开始进行说明（尚未按您的预期工作）：

import scrapy


class HandleSpider(scrapy.Spider):
    name = "handle"
    start_urls = (
        'https://httpbin.org/get',
        'https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F',
    )
    def parse(self, response):
        self.logger.info("got response for %r" % response.url)

现在，蜘蛛请求 2 个页面，第二个页面应该重定向到http://www.example.com http://www.example.com

$ scrapy runspider test.py
2016-09-30 11:28:17 [scrapy] INFO: Scrapy 1.1.3 started (bot: scrapybot)
2016-09-30 11:28:18 [scrapy] DEBUG: Crawled (200) <GET https://httpbin.org/get> (referer: None)
2016-09-30 11:28:18 [scrapy] DEBUG: Redirecting (302) to <GET http://example.com/> from <GET https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F>
2016-09-30 11:28:18 [handle] INFO: got response for 'https://httpbin.org/get'
2016-09-30 11:28:18 [scrapy] DEBUG: Crawled (200) <GET http://example.com/> (referer: None)
2016-09-30 11:28:18 [handle] INFO: got response for 'http://example.com/'
2016-09-30 11:28:18 [scrapy] INFO: Spider closed (finished)

302 的处理者是RedirectMiddleware自动并且它不会传递给您的回调。

测试2（仍然不太正确）

让我们配置蜘蛛来处理回调中的 301 和 302，using handle_httpstatus_list https://doc.scrapy.org/en/latest/topics/downloader-middleware.html?#module-scrapy.downloadermiddlewares.redirect:

import scrapy


class HandleSpider(scrapy.Spider):
    name = "handle"
    start_urls = (
        'https://httpbin.org/get',
        'https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F',
    )
    handle_httpstatus_list = [301, 302]
    def parse(self, response):
        self.logger.info("got response %d for %r" % (response.status, response.url))

让我们运行一下：

$ scrapy runspider test.py
2016-09-30 11:33:32 [scrapy] INFO: Scrapy 1.1.3 started (bot: scrapybot)
2016-09-30 11:33:32 [scrapy] DEBUG: Crawled (200) <GET https://httpbin.org/get> (referer: None)
2016-09-30 11:33:32 [scrapy] DEBUG: Crawled (302) <GET https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F> (referer: None)
2016-09-30 11:33:33 [handle] INFO: got response 200 for 'https://httpbin.org/get'
2016-09-30 11:33:33 [handle] INFO: got response 302 for 'https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F'
2016-09-30 11:33:33 [scrapy] INFO: Spider closed (finished)

在这里，我们错过了重定向。

测试3（工作）

Do the 与重定向中间件相同 https://github.com/scrapy/scrapy/blob/ebef6d7c6dd8922210db8a4a44f48fe27ee0cd16/scrapy/downloadermiddlewares/redirect.py#L54但在蜘蛛回调中：

from six.moves.urllib.parse import urljoin

import scrapy
from scrapy.utils.python import to_native_str


class HandleSpider(scrapy.Spider):
    name = "handle"
    start_urls = (
        'https://httpbin.org/get',
        'https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F',
    )
    handle_httpstatus_list = [301, 302]
    def parse(self, response):
        self.logger.info("got response %d for %r" % (response.status, response.url))

        # do something with the response here...

        # handle redirection
        # this is copied/adapted from RedirectMiddleware
        if response.status >= 300 and response.status < 400:

            # HTTP header is ascii or latin1, redirected url will be percent-encoded utf-8
            location = to_native_str(response.headers['location'].decode('latin1'))

            # get the original request
            request = response.request
            # and the URL we got redirected to
            redirected_url = urljoin(request.url, location)

            if response.status in (301, 307) or request.method == 'HEAD':
                redirected = request.replace(url=redirected_url)
                yield redirected
            else:
                redirected = request.replace(url=redirected_url, method='GET', body='')
                redirected.headers.pop('Content-Type', None)
                redirected.headers.pop('Content-Length', None)
                yield redirected

再次运行蜘蛛：

$ scrapy runspider test.py
2016-09-30 11:45:20 [scrapy] INFO: Scrapy 1.1.3 started (bot: scrapybot)
2016-09-30 11:45:21 [scrapy] DEBUG: Crawled (302) <GET https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F> (referer: None)
2016-09-30 11:45:21 [scrapy] DEBUG: Crawled (200) <GET https://httpbin.org/get> (referer: None)
2016-09-30 11:45:21 [handle] INFO: got response 302 for 'https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F'
2016-09-30 11:45:21 [handle] INFO: got response 200 for 'https://httpbin.org/get'
2016-09-30 11:45:21 [scrapy] DEBUG: Crawled (200) <GET http://example.com/> (referer: https://httpbin.org/redirect-to?url=http%3A%2F%2Fexample.com%2F)
2016-09-30 11:45:21 [handle] INFO: got response 200 for 'http://example.com/'
2016-09-30 11:45:21 [scrapy] INFO: Spider closed (finished)

我们被重定向到http://www.example.com http://www.example.com我们也通过回调得到了响应。