(8)分布式下的爬蟲Scrapy應該如何做-圖片下載(源碼放送)

  轉載主注明出處：http://www.cnblogs.com/codefish/p/4968260.html

 

  在爬蟲中，我們遇到比較多需求就是文件下載以及圖片下載，在其它的語言或者框架中，我們可能在經過數據篩選，然后異步的使用文件下載類來達到目的，Scrapy框架中本身已經實現了文件及圖片下載的文件，相當的方便，只要幾行代碼，就可以輕松的搞定下載。下面我將演示如何使用scrapy下載豆瓣的相冊首頁內容。

優點介紹：

   1)自動去重

   2)異步操作，不會阻塞

   3)可以生成指定尺寸的縮略圖

   4)計算過期時間

   5)格式轉化

 

 

編碼過程：

一，定義Item 

# -*- 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
from scrapy import Item,Field



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

 

 

二，定義spider 

#coding=utf-8
from scrapy.spiders import Spider
import re
from douban_imgs.items import DoubanImgsItem
from scrapy.http.request import Request
# please pay attention to the encoding of info,otherwise raise error
import sys
reload(sys)
sys.setdefaultencoding('utf8')


class download_douban(Spider):
    name = 'download_douban'
    def __init__(self, url='152686895', *args, **kwargs):
        self.allowed_domains = ['douban.com']
        self.start_urls = [
                'http://www.douban.com/photos/album/%s/' %(url) ]
        #call the father base function
        self.url = url
        super(download_douban, self).__init__(*args, **kwargs)

    def parse(self, response):
        """
        :type response: response infomation
        """
        list_imgs = response.xpath('//div[@class="photolst clearfix"]//img/@src').extract()
        if list_imgs:
            item = DoubanImgsItem()
            item['image_urls'] = list_imgs
            yield item

 

三，定義piepline

# -*- 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.pipelines.images import ImagesPipeline
from scrapy.exceptions import DropItem
from scrapy import Request
from scrapy import log



class DoubanImgsPipeline(object):
    def process_item(self, item, spider):
        return item



class DoubanImgDownloadPieline(ImagesPipeline):
    def get_media_requests(self,item,info):
        for image_url in item['image_urls']:

            yield Request(image_url)

    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

 

 

四，定義setting.py，啟用item處理器

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


IMAGES_STORE='C:\\doubanimgs'

IMAGES_EXPIRES = 90

 

運行效果：

 

github地址：https://github.com/BruceDone/scrapy_demo

 

  轉載主注明出處：http://www.cnblogs.com/codefish/p/4968260.html

  如果scrapy或者爬蟲系列對你有幫助，請推薦一下，我后續會更新更多的爬蟲系列