• 第三次作业

    作业一

        要求：指定一个网站，爬取这个网站中的所有的所有图片，例如中国气象网（http://www.weather.com.cn）。分别使用单线程和多线程的方式爬取

         输出信息:将下载的Url信息在控制台输出，并将下载的图片存储在images子文件中，并给出截图。

    单线程：

     1 #  031804127王璐
 2 
 3 from wsgiref import headers
 4 from bs4 import BeautifulSoup
 5 from bs4 import UnicodeDammit
 6 import urllib.request
 7 
 8 
 9 def imageSpider(start_url):
10     try:
11         urls = []
12         req = urllib.request.Request(start_url, headers=headers)
13         data = urllib.request.urlopen(req)
14         data = data.read()
15         dammit = UnicodeDammit(data, ["utf-8", "gbk"])
16         data = dammit.unicode_markup
17         soup = BeautifulSoup(data, 'lxml')
18         images = soup.select("img")  # 爬取所有图片
19         for image in images:
20             try:
21                 # 获取图片的url
22                 src = image["src"]
23                 url = urllib.request.urljoin(start_url, src)
24                 if url not in urls:
25                     urls.append(url)  # 没有被爬取过的图片就添加
26                     print(url)
27                     download(url)  # 下载图片
28             except Exception as err:
29                 print(err)
30     except Exception as err:
31         print(err)
32 
33 
34 def download(url):
35     global count  # 声明全局变量count
36     try:
37         count = count + 1
38         if (url[len(url) - 4] == "."):  # 图片格式后缀为三位，格式后缀前面的字符为"."
39             ext = url[len(url) - 4:]  # 获取图片格式
40         else:
41             ext = ""
42         # 获取图片文件
43         req = urllib.request.Request(url, headers=headers)
44         data = urllib.request.urlopen(req, timeout=100)
45         data = data.read()
46         # 存储图片到指定位置并命名
47         fobj = open("D:\images(1)\" + str(count) + ext, "wb")  # 以二进制形式打开文件
48         fobj.write(data)
49         fobj.close()
50         print("downloaded" + str(count) + ext)
51     except Exception as err:
52         print(err)
53 
54 
55 start_url = "http://www.weather.com.cn"
56 headers = {"User-Agent": "Mozilla/5.0(Windows;U;Windows NT 6.0 x64;en-US;rv:1.9pre)Gecko/2008072421 Minefield/3.0.2pre"}
57 count = 0  # 用于记录爬取图片的个数
58 imageSpider(start_url)

     实验结果：

    多线程：

     1 # 031804127王璐
 2 
 3 from bs4 import BeautifulSoup
 4 from bs4 import UnicodeDammit
 5 import urllib.request
 6 import threading
 7 
 8 
 9 def imageSpider(start_url):
10     global threads
11     global count
12     try:
13         urls = []
14         req = urllib.request.Request(start_url, headers=headers)
15         data = urllib.request.urlopen(req)
16         data = data.read()
17         dammit = UnicodeDammit(data, ["utf-8", "gbk"])
18         data = dammit.unicode_markup
19         soup = BeautifulSoup(data, 'lxml')
20         images = soup.select("img")  # 爬取所有图片
21         for image in images:
22             try:
23                 # 获取图片的url
24                 src = image["src"]
25                 url = urllib.request.urljoin(start_url, src)
26                 if url not in urls:
27                     print(url)
28                     count = count + 1
29                     T = threading.Thread(target=download, args=(url, count))
30                     T.setDaemon(False)
31                     T.start()
32                     threads.append()
33             except Exception as err:
34                 print(err)
35     except Exception as err:
36         print(err)
37 
38 
39 def download(url, count):
40     try:
41         if (url[len(url) - 4] == "."):  # 图片格式后缀为三位，格式后缀前面的字符为"."
42             ext = url[len(url) - 4:]  # 获取图片格式
43         else:
44             ext = ""
45         # 获取图片文件
46         req = urllib.request.Request(url, headers=headers)
47         data = urllib.request.urlopen(req, timeout=100)
48         data = data.read()
49         # 存储图片到指定位置并命名
50         fobj = open("D:\images(2)\" + str(count) + ext, "wb")  # 以二进制形式打开文件
51         fobj.write(data)
52         fobj.close()
53         print("downloaded" + str(count) + ext)
54     except Exception as err:
55         print(err)
56 
57 start_url = "http://www.weather.com.cn"
58 headers = {"User-Agent": "Mozilla/5.0(Windows;U;Windows NT 6.0 x64;en-US;rv:1.9pre)Gecko/2008072421 Minefield/3.0.2pre"}
59 count = 0  # 用于记录爬取图片的个数
60 threads = []
61 
62 imageSpider(start_url)
63 
64 for t in threads:
65     t.join()
66 print("The End")

    实验结果：

    实验心得：

      与单线程相比，多线程的效率更高，因为它可以在后台同时下载多张图片，多张图片的下载互不干扰，不会像单线程那样会因某个图像下载缓慢而效率低下。使用多线程时，要注意前后台线程的区别，也要合理运用线程锁，防止多线程冲突。

    作业二

        要求：使用scrapy框架复现作业一

         输出信息：同作业一

    DownloadImaes.py

     1 # 031804127王璐
 2 import scrapy
 3 from Images.items import ImagesItem
 4 
 5 
 6 class DownloadimagesSpider(scrapy.Spider):
 7     name = 'DownloadImages'
 8     start_urls = ['http://www.weather.com.cn/']
 9 
10     def parse(self, response):
11         data = response.body.decode()
12         selector = scrapy.Selector(text=data)
13         item = ImagesItem()
14         item['img_urls'] = selector.xpath("//img/@src").extract()  # 提取图片链接
15         # print 'image_urls',item['image_urls']
16         yield item

    pipelines.py

     1 # 031804127王璐
 2 
 3 import os
 4 import urllib.request
 5 from Images.settings import IMAGES_STORE
 6 
 7 
 8 class ImagesPipeline(object):
 9     def process_item(self, item, spider):
10         dir_path = IMAGES_STORE + '/' + spider.name  # 存储路径
11         if not os.path.exists(dir_path):
12             os.makedirs(dir_path)
13         for image_url in item['img_urls']:
14             list_name = image_url.split('/')
15             file_name = list_name[len(list_name) - 1]  # 图片名称
16             # print 'filename',file_name
17             file_path = dir_path + '/' + file_name
18             # print 'file_path',file_path
19             if os.path.exists(file_name):
20                 continue
21             req = urllib.request.Request(image_url)
22             data = urllib.request.urlopen(req, timeout=100)
23             data = data.read()
24             fobj = open(file_path, "wb")
25             fobj.write(data)
26             fobj.close()
27         return item

    items.py

    1 # 031804127王璐
2 
3 import scrapy
4 
5 
6 class ImagesItem(scrapy.Item):
7     # define the fields for your item here like:
8     # name = scrapy.Field()
9     img_urls = scrapy.Field()

    settings.py

     1 BOT_NAME = 'Images'
 2 
 3 SPIDER_MODULES = ['Images.spiders']
 4 NEWSPIDER_MODULE = 'Images.spiders'
 5 
 6 ITEM_PIPELINES = {
 7     'Images.pipelines.ImagesPipeline': 300
 8 }
 9 # 开启报头
10 USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/536.5 (KHTML, like Gecko) ' 
11              'Chrome/19.0.1084.54 Safari/536.5 '
12 
13 IMAGES_STORE = 'C:/My work/pachong/test1/Images'
14 DOWNLOAD_DELAY = 0.25
15 ROBOTSTXT_OBEY = False

    实验结果：

    实验心得：

      了解和学习了运用scrapy框架进行爬虫，其实实现方式和作业一差不多，但是由于scrapy框架的特点，需要将不同的的功能分成不同的py文件书写，条理清晰的同时，也具有更加强大的爬虫功能。Xpath语法我自认为是目前学过的最方便的查找HTML元素的语法，但是还需多加练习。

      然后由于中国天气网中的图片链接都是这种形式

    所以我没有运用书本例题用数字+提取'.'后图片格式命名图片的方式，而是直接用‘/’分割图片地址，直接用分割完成后的最后一个字符串命名图片。

    作业三

        要求：使用scrapy框架爬取股票相关信息

         候选网站：东方财富网：https://www.eastmoney.com/

                          新浪股票：http://finance.sina.com.cn/stock/

    stocks.py

     1 # 031804127王璐
 2 
 3 import json
 4 import scrapy
 5 from Gupiao.items import GupiaoItem
 6 
 7 
 8 class StocksSpider(scrapy.Spider):
 9     name = 'stocks'
10     start_urls = [
11         'http://49.push2.eastmoney.com/api/qt/clist/get?cb=jQuery11240918880626239239_1602070531441&pn=1&pz=20&po=1&np=3&ut=bd1d9ddb04089700cf9c27f6f7426281&fltt=2&invt=2&fid=f3&fs=m:1+t:2,m:1+t:23&fields=f1,f2,f3,f4,f5,f6,f7,f8,f9,f10,f12,f13,f14,f15,f16,f17,f18,f20,f21,f23,f24,f25,f22,f11,f62,f128,f136,f115,f152&_=1602070531442']
12 
13     def parse(self, response):
14         jsons = response.text[41:][:-2]  # 将前后用不着的字符排除
15         text_json = json.loads(jsons)
16         for data in text_json['data']['diff']:
17             item = GupiaoItem()
18             item["f12"] = data['f12']
19             item["f14"] = data['f14']
20             item["f2"] = data['f2']
21             item["f3"] = data['f3']
22             item["f4"] = data['f4']
23             item["f5"] = data['f5']
24             item["f6"] = data['f6']
25             item["f7"] = data['f7']
26             yield item
27         print("完成")
28 
29         # 再爬取后10页的内容
30         for i in range(2, 11):
31             new_url = 'http://49.push2.eastmoney.com/api/qt/clist/get?cb=jQuery11240918880626239239_1602070531441&pn=' + str(
32                 i) + '&pz=20&po=1&np=3&ut=bd1d9ddb04089700cf9c27f6f7426281&fltt=2&invt=2&fid=f3&fs=m:1+t:2,m:1+t:23&fields=f1,f2,f3,f4,f5,f6,f7,f8,f9,f10,f12,f13,f14,f15,f16,f17,f18,f20,f21,f23,f24,f25,f22,f11,f62,f128,f136,f115,f152&_=1602070531442'
33         if new_url:
34             yield scrapy.Request(new_url, callback=self.parse)

    pipelines.py

     1 # 031804127王璐
 2 
 3 class GupiaoPipeline:
 4     count = 0
 5     print("序号	", "代码	", "名称	", "最新价	 ", "涨跌幅	 ", "跌涨额	", "成交量	", "成交额	", "涨幅	")
 6 
 7     # 打印结果
 8     def process_item(self, item, spider):
 9         try:
10             self.count += 1
11             print(str(self.count) + "	", item['f12'] + "	", item['f14'] + "	", str(item['f2']) + "	",
12                   str(item['f3']) + "%	", str(item['f4']) + "	", str(item['f5']) + "	", str(item['f6']) + "	",
13                   str(item['f7']) + "%")
14 
15         except Exception as err:
16             print(err)
17 
18         return item

    items.py

     1 # 031804127王璐
 2 
 3 import scrapy
 4 
 5 
 6 class GupiaoItem(scrapy.Item):
 7     # define the fields for your item here like:
 8     # name = scrapy.Field()
 9     f12 = scrapy.Field()
10     f14 = scrapy.Field()
11     f2 = scrapy.Field()
12     f3 = scrapy.Field()
13     f4 = scrapy.Field()
14     f5 = scrapy.Field()
15     f6 = scrapy.Field()
16     f7 = scrapy.Field()

    settings.py

     1 BOT_NAME = 'Gupiao'
 2 
 3 SPIDER_MODULES = ['Gupiao.spiders']
 4 NEWSPIDER_MODULE = 'Gupiao.spiders'
 5 
 6 ROBOTSTXT_OBEY = False # 必须设为False，否则无法打印结果
 7 
 8 ITEM_PIPELINES = {
 9     'Gupiao.pipelines.GupiaoPipeline': 300,
10 }

    实验结果：

    实验心得：

      实现方式同样是和之前使用request库差不多。但是在我前几次测试的时候，发现一直打印不出结果，经过网上查找后发现需要在settings.py中把ROBOTSTXT_OBEY设置为false。
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  • 原文地址：https://www.cnblogs.com/wlululu/p/13831349.html
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