16-爬虫之scrapy框架手动请求发送实现全站数据爬取03

scrapy的手动请求发送实现全站数据爬取

• yield scrapy.Reques(url,callback) 发起的get请求
  • callback指定解析函数用于解析数据
• yield scrapy.FormRequest（url,callback,formdata）发起的post请求
  • formdata：字典，请求参数
• 为什么start_urls列表中的url会被自动进行get请求的发送？
  • 因为列表中的url其实是被start_requests这个父类方法实现的get请求

# 父类方法：这个是该方法的原始实现
def start_requests(self):
    for u in self.start_urls:
        yield scrapy.Request(url=url,callback=self.parse)

• 如何将start_urls中的url默认进行post请求发送？

# 重写父类方法默认进行post请求发送
def start_requests(self):
    for u in self.start_urls:
        yield scrapy.FormRequest(url=url,callback=self.parse)

开始

创建一个爬虫工程：scrapy startproject proName
进入工程目录创建爬虫源文件：scrapy genspider spiderName www.xxx.com
执行工程：scrapy crawl spiderName

配置pipelines.py文件

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://docs.scrapy.org/en/latest/topics/item-pipeline.html


# useful for handling different item types with a single interface
from itemadapter import ItemAdapter


class GpcPipeline:
    def process_item(self, item, spider):
        print(item)
        return item

配置items.py文件

# Define here the models for your scraped items
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/items.html

import scrapy


class GpcItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    title = scrapy.Field()
    content = scrapy.Field()

配置settings.py配置文件

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

BOT_NAME = 'gpc'

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


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#设置UA伪装
USER_AGENT = 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36'
LOG_LEVEL = 'ERROR' #指定类型日志的输出(只输出错误信息)

# 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://docs.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',
#}

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

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

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

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

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.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://docs.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'

爬虫源文件 una.py

import scrapy
from gpc.items import GpcItem

class UnaSpider(scrapy.Spider):
    name = 'una'
    #allowed_domains = ['www.baidu.com']
    start_urls = ['https://duanziwang.com/category/经典段子/1/']

    #定义通用url模板
    url = 'https://duanziwang.com/category/经典段子/%d/'
    page_num = 2

    # 将段子网中所有页码对应的数据进行爬取
    def parse(self, response):
        # 数据解析名称和内容
        article_list = response.xpath('/html/body/section/div/div/main/article')
        for article in article_list:
            # 我们可以看见解析出来的内容不是字符串数据，说明和etree中xpath使用方式不同
            # xpath返回的列表中存储是Selector对象，说明我们想要的字符串数据被存储在了该对象的data属性中
            # extract()就是将data属性值取出
            # 调用extract_first() 将列表中第一个列表元素表示的Selector对象中的data值取出
            title = article.xpath("./div[1]/h1/a/text()").extract_first()
            content = article.xpath("./div[2]/p/text()").extract_first()
            # 实例化一个item类型的对象，将解析到的数据存储到该对象中
            item = GpcItem()
            # 不能使用item. 来调用数据
            item['title'] = title
            item['content'] = content
            yield item
        if self.page_num < 5:#结束递归的条件

            new_url = format(self.url%self.page_num)#其他页码对应的完整url
            self.page_num += 1
            #对新的页码对应的url发起请求（手动发起get请求）
            yield scrapy.Request(url=new_url,callback=self.parse)#递归请求回调提交给parse进行解析

结果展示