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