scrapy模拟登陆人人网

这个项目，也不难，但有一点我真的不太明白，搞了半天也没搞懂，就是发送post请求的这个地址，是怎么找到的，我玩了一上午的network，各种博客翻了一遍，也没找到，希望有缘人可以给我解释一下，同时我自己也不放弃追求真理，日后有所领悟，会在底部最下方，添加解决方案。

创建新项目
如何创建的废话，我就不说了，直接给出我创建后的结构图。

start_renren.py是我创建的启动项。
配置setting

# -*- coding: utf-8 -*-

# Scrapy settings for renren_login project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://doc.scrapy.org/en/latest/topics/settings.html
#     https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://doc.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'renren_login'

SPIDER_MODULES = ['renren_login.spiders']
NEWSPIDER_MODULE = 'renren_login.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'renren_login (+http://www.yourdomain.com)'

# Obey robots.txt rules
ROBOTSTXT_OBEY = False

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://doc.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
  'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
  'Accept-Language': 'en',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.142 Safari/537.36'
}

# Enable or disable spider middlewares
# See https://doc.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'renren_login.middlewares.RenrenLoginSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'renren_login.middlewares.RenrenLoginDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See https://doc.scrapy.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See https://doc.scrapy.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    'renren_login.pipelines.RenrenLoginPipeline': 300,
#}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

renren.py
这部分是这次学习的重点内容：
我们先看看源文件start_request函数的调用方法吧！
查看函数源文件的方法是：按住ctrl然后点击目标函数即可查看。

我们把注意力放在else之后这部分函数：

显然yield函数是遍历start_ur里面的一切url且dont_filter = true不过滤重复的url，默认使用get的方法，故不符合我们发送的post请求，我们想要发送post请求可以重写start_url去覆盖原有的start_url。

 def start_requests(self):
        url = 'http://www.renren.com/PLogin.do'#搞不明白这个网址哪里找到的
        data = {
            'email':'970138074@qq.com',
            'password':'pythonspider'
        }
        request = scrapy.FormRequest(url,formdata=data,callback=self.parse_page)
        yield request

为了证明证明我们已经登录成功，我们查看一下一个就郑晴的美女的主页，我们将网页信息保存一下：

   def parse_page(self,response):
        url = 'http://www.renren.com/970771065/profile?ref=hotnewsfeed&sfet=701&fin=1&fid=28280773367&ff_id=970771065&platform=10&expose_time=1564124401'
        request =  scrapy.Request(url,callback=self.parse_text)
        yield request
        
    def parse_text(self, response):
        with open('renren.html','w',encoding='utf-8')as fp:
            fp.write(response.text)

得到的数据对比一下证明抓取无误：

下面给出完整代码：
renren.py:

# -*- coding: utf-8 -*-
import scrapy


class RenrenSpider(scrapy.Spider):
    name = 'renren'
    allowed_domains = ['renren.com']
    start_urls = ['http://renren.com/']

    def start_requests(self):
        url = 'http://www.renren.com/PLogin.do'#搞不明白这个网址哪里找到的
        data = {
            'email':'970138074@qq.com',
            'password':'pythonspider'
        }
        request = scrapy.FormRequest(url,formdata=data,callback=self.parse_page)
        yield request

    def parse_page(self,response):
        url = 'http://www.renren.com/970771065/profile?ref=hotnewsfeed&sfet=701&fin=1&fid=28280773367&ff_id=970771065&platform=10&expose_time=1564124401'
        request =  scrapy.Request(url,callback=self.parse_text)
        yield request

    def parse_text(self, response):
        with open('renren.html','w',encoding='utf-8')as fp:
            fp.write(response.text)

总结一下：

要发送post请求，推荐使用'scrapy.FormRequest'方法，可以方便的指定表单数据。

如果想一开始就发送post请求，就要重写‘start_request’方法，在这个方法中发送post请求。

欢迎路过的朋友点个喜欢，也请路过的朋友们留下宝贵的意见和建议