python、scrapy下编写妹子图爬虫程序

软件、框架的安装主要参考：http://www.jianshu.com/p/a03aab073a35

Scrapy官方文档：https://docs.scrapy.org/en/latest/intro/install.html（安装、爬虫都有参考的）

程序逻辑、流程主要参考http://cuiqingcai.com/4421.html，

其他细节百度

环境：

macOS10.12.3

Python2.7

Scrapy1.3.3

一、软件（python）、框架(scrapy)的安装

mac自带Python，根据Scrapy官网建议，最好下载最新的Python版本安装

1、安装pip工具包的支撑环境

各个电脑的情况不一样，支撑包的情况也不一样，反正一句话：缺什么就装什么，我采用Homebrew

2、pip源修改（镜像地址）

这个一定要做，默认地址访问速度特别慢，翻墙了都很慢，最后我的总结是：有一半的时间都是因为这个原因导致的

首先创建配置文件，默认情况下Mac端好像是没有pip的配置文件的，我们需要自行创建。
打开终端，在HOME下创建.pip目录：
echo $HOME
mkdir .pip
接下来创建配置文件pip.conf：
touch pip.conf
接下来编辑配置文件，随便使用什么编辑器打开刚刚新建的pip.conf文件，输入以下两行：

[global]
index-url = http://pypi.mirrors.ustc.edu.cn/simple
输入完成后保存退出即可，至此，pip源就修改完了

国内的镜像较多，参考：http://it.taocms.org/08/8567.htm、http://www.jianshu.com/p/a03aab073a35哪个行就用哪个

3、HOME目录进行Command Line Tools安装，终端下执行

xcode-select --install

4、安装Scrapy，

终端执行pip install Scrapy

如果提示失败，自行看失败原因，例如跟six有关，就升级six包：sudo pip install six

通过pip你可以安装、升级大部分支撑包，简单一句：缺哪个就安装哪个包，哪个包版本不对，就升级哪个。这里有Scrapy依赖包的关系和版本：https://pypi.python.org/pypi/Scrapy/1.3.3，链接根据需要访问不同的Scrapy版本页面

我遇到的另一个问题主要是Scrapy需要支撑包版本问题，和终端账户问题。建议多尝试，采用root账户统一安装

二、编写爬虫爬取mzitu全站图片：

Scrapy官方文档和http://cuiqingcai.com/4421.html写的很清楚了，我就不班门弄斧，直接贴出代码：

run.py，运行程序：

from scrapy.cmdline import execute
execute(['scrapy', 'crawl', 'mzitu'])

items.py：用来定义Item有哪些属性

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

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

import scrapy


class MzituScrapyItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    name = scrapy.Field()
    image_urls = scrapy.Field()
    images = scrapy.Field()
    image_paths = scrapy.Field()

pipelines.py

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

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


from scrapy import Request
from scrapy.pipelines.images import ImagesPipeline
from scrapy.exceptions import DropItem
import re


class MzituScrapyPipeline(ImagesPipeline):

    def file_path(self, request, response=None, info=None):
        """
        :param request: 每一个图片下载管道请求
        :param response: 
        :param info: 
        :param strip :清洗Windows系统的文件夹非法字符，避免无法创建目录
        :return: 每套图的分类目录
        """
        item = request.meta['item']
        FolderName = item['name']
        image_guid = request.url.split('/')[-1]
        filename = u'full/{0}/{1}'.format(FolderName, image_guid)
        return filename
 
    def get_media_requests(self, item, info):
        """
        :param item: spider.py中返回的item
        :param info: 
        :return: 
        """
        for img_url in item['image_urls']:
            yield Request(img_url, meta={'item': item})
 
 
    def item_completed(self, results, item, info):
        image_paths = [x['path'] for ok, x in results if ok]
        if not image_paths:
            raise DropItem("Item contains no images")
        item['image_paths'] = image_paths
        return item

 settings.py，项目设置文件：

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

# Scrapy settings for mzitu_scrapy 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 = 'mzitu_scrapy'

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


ITEM_PIPELINES = {'mzitu_scrapy.pipelines.MzituScrapyPipeline': 300}
IMAGES_STORE = '/tmp/images'
IMAGES_EXPIRES = 1


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

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

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

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.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 http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'mzitu_scrapy.middlewares.MzituScrapySpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'mzitu_scrapy.middlewares.MyCustomDownloaderMiddleware': 543,
#}

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

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    'mzitu_scrapy.pipelines.MzituScrapyPipeline': 300,
#}

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

spider.py，主程序：

# -*- coding: UTF-8 -*- 

from scrapy import Request
from scrapy.spiders import CrawlSpider, Rule
from scrapy.linkextractors import LinkExtractor
from mzitu_scrapy.items import MzituScrapyItem


class Spider(CrawlSpider):
    name = 'mzitu'
    allowed_domains = ['mzitu.com']
    start_urls = ['http://www.mzitu.com/']
    my_img_urls = []
    rules = (
        Rule(LinkExtractor(allow=('http://www.mzitu.com/d{1,6}',), deny=('http://www.mzitu.com/d{1,6}/d{1,6}')), callback='parse_item', follow=True),
    )


    def parse_item(self, response):
        """
        :param response: 下载器返回的response
        :return:
        """
        item = MzituScrapyItem()
        # max_num为页面最后一张图片的位置
        max_num = response.xpath("descendant::div[@class='main']/div[@class='content']/div[@class='pagenavi']/a[last()-1]/span/text()").extract_first(default="N/A")
        for num in range(1, int(max_num)):
            # page_url 为每张图片所在的页面地址
            page_url = response.url + '/' + str(num)
            yield Request(page_url, callback=self.img_url)        


    def img_url(self, response):
        """取出图片URL 并添加进self.img_urls列表中
        :param response:
        :param img_url 为每张图片的真实地址
        """
        item = MzituScrapyItem()
        name = response.xpath("descendant::div[@class='main-image']/descendant::img/@alt").extract_first(default="N/A")
        img_urls = response.xpath("descendant::div[@class='main-image']/descendant::img/@src").extract()
        item['image_urls'] = img_urls
        item['name']  = name
        return item

项目结构如下：

最后终端进入项目目录，执行：

python run.py crawl mzitu_scrapy

 

如果遇到问题多找百度答案，坑还是不少的。

 

我这里提几点：

1、Scrapy是默认给文件按照hash来命名的，想要文件原来的名字就覆写file_path方法，网络上写的覆写方法完全没有问题

2、如果想给文件归类放不同的文件夹怎么办？所谓文件夹不过是路径而已，一样是修改file_path，只不过要给n个文件写入同一个文件夹，我的思路就是一个item[name]对应n个文件，该name就是文件夹名称。注意http://cuiqingcai.com/4421.html的主程序是错的，文件夹名称和文件根本对不上，有严重的逻辑问题。为了这个问题我找了好久答案，一直都以为是覆写file_path方法的思路是错的，最后才发现原来主程序中name和文件对不上导致的

3、xpath语法可以上http://www.w3school.com.cn/xpath/index.asp现学，不难，可以结合chrome的一个xpath插件（xpath helper）在按照xpath语法修改（我基本是用该插件来验证写的语句对不对）

 

最后，如果你因为防火墙的问题，纠结上不了chrome应用商店，安装不了xpath helper。想办法翻墙即可。

 

文中有错误，或改善的地方，欢迎指正，大家一起探讨