19-爬虫之scrapy框架大文件下载06

大文件下载
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

大文件数据是在管道中请求到的

下载管道类是scrapy封装好的直接调用即可：

from scrapy.pipelines.images import ImagesPipeline # 该管道提供数据下载功能（图片视频音频皆可使用该类）

重写管道类的三个方法：

def get_media_requests

• 对图片地址发起请求

def file_path

• 返回图片名称即可

def item_completed

• 返回item，将其返回给下一个即将被执行的管道类

在配置文件中添加 IMAGES_STORE

• IMAGES_STORE=‘dirname’

img.py 爬虫源文件

import scrapy
from imgPro.items import ImgproItem

class ImgSpider(scrapy.Spider):
    name = 'img'
    #allowed_domains = ['www.xxx.com']
    start_urls = ['http://www.521609.com/daxuemeinv/']

    def parse(self, response):
        li_list = response.xpath('//*[@id="content"]/div[2]/div[2]/ul/li')
        for li in li_list:
            img_src = 'http://www.521609.com'+li.xpath('./a[1]/img/@src').extract_first() #图片url
            img_name = li.xpath('./a[1]/img/@alt').extract_first()+'.jpg'#图片名字

            item = ImgproItem()
            item['name'] = img_name
            item['src'] = img_src

            yield item

items.py

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

import scrapy


class ImgproItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    name = scrapy.Field()
    src = scrapy.Field()

settings.py

# Scrapy settings for imgPro 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 = 'imgPro'

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


# Crawl responsibly by identifying yourself (and your website) on the user-agent
USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36"

# Obey robots.txt rules
ROBOTSTXT_OBEY = False
LOG_LEVEL = "ERROR"

IMAGES_STORE = 'imgLibs' #定义存储文件夹（没有的话会自动给创建）
# 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 = {
#    'imgPro.middlewares.ImgproSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'imgPro.middlewares.ImgproDownloaderMiddleware': 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 = {
   'imgPro.pipelines.ImgsproPipeline': 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'

pipelines.py

# 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

# 该默认管道无法帮我们进行数据请求，因此该管道我们就不使用
# class ImgproPipeline:
#     def process_item(self, item, spider):
#         return item

# 管道需要接受item中的图片地址和名称，然后在管道中请求到图片的数据对其进行持久化存储
from scrapy.pipelines.images import ImagesPipeline # 该管道提供数据下载功能（图片视频音频皆可使用该类）
import scrapy
class ImgsproPipeline(ImagesPipeline):
    # 根据图片地址发起请求
    def get_media_requests(self, item, info):
        print(item)
        yield scrapy.Request(url=item['src'],meta={'item':item})

    # 返回图片名称即可
    def file_path(self, request, response=None, info=None):
        # 通过request获取meta
        item = request.meta['item']
        filePath = item['name']
        return filePath #返回图片名称

    # 我们将item传递给下一个即将被执行的管道类
    def item_completed(self, results, item, info):
        return item

结果展示

scrapy的settings.py配置文件介绍

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


# Scrapy settings for demo1 project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html


BOT_NAME = ''   #Scrapy项目的名字,这将用来构造默认 User-Agent,同时也用来log,当您使用 startproject 命令创建项目时其也被自动赋值。


SPIDER_MODULES = ['']   #Scrapy搜索spider的模块列表 默认: [xxx.spiders]
NEWSPIDER_MODULE = ''   #使用 genspider 命令创建新spider的模块。默认: 'xxx.spiders'




#爬取的默认User-Agent，除非被覆盖
#USER_AGENT =‘’

#如果启用,Scrapy将会采用 robots.txt策略
ROBOTSTXT_OBEY = True


#Scrapy downloader 并发请求(concurrent requests)的最大值,默认: 16
#CONCURRENT_REQUESTS = 32


#为同一网站的请求配置延迟（默认值：0）
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs  
#DOWNLOAD_DELAY = 3   下载器在下载同一个网站下一个页面前需要等待的时间,该选项可以用来限制爬取速度,减轻服务器压力。同时也支持小数:0.25 以秒为单位


    
#下载延迟设置只有一个有效
#CONCURRENT_REQUESTS_PER_DOMAIN = 16   对单个网站进行并发请求的最大值。
#CONCURRENT_REQUESTS_PER_IP = 16       对单个IP进行并发请求的最大值。如果非0,则忽略 CONCURRENT_REQUESTS_PER_DOMAIN 设定,使用该设定。 也就是说,并发限制将针对IP,而不是网站。该设定也影响 DOWNLOAD_DELAY: 如果 CONCURRENT_REQUESTS_PER_IP 非0,下载延迟应用在IP而不是网站上。


#禁用Cookie（默认情况下启用）
#COOKIES_ENABLED = False


#禁用Telnet控制台（默认启用）
#TELNETCONSOLE_ENABLED = False 


#覆盖默认请求标头：
#DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
#}


#启用或禁用蜘蛛中间件
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'demo1.middlewares.Demo1SpiderMiddleware': 543,
#}


#启用或禁用下载器中间件
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'demo1.middlewares.MyCustomDownloaderMiddleware': 543,
#}


#启用或禁用扩展程序
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}


#配置项目管道
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    'demo1.pipelines.Demo1Pipeline': 300,
#}


#启用和配置AutoThrottle扩展（默认情况下禁用）
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True


#初始下载延迟
#AUTOTHROTTLE_START_DELAY = 5


#在高延迟的情况下设置的最大下载延迟
#AUTOTHROTTLE_MAX_DELAY = 60




#Scrapy请求的平均数量应该并行发送每个远程服务器
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0


#启用显示所收到的每个响应的调节统计信息：
#AUTOTHROTTLE_DEBUG = False


#启用和配置HTTP缓存（默认情况下禁用）
# See http://scrapy.readthedocs.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'