本次爬取自如网房源信息所用到的知识点:
1. requests get请求
2. lxml解析html
3. Xpath
4. MongoDB存储
正文
1.分析目标站点
1. url: http://hz.ziroom.com/z/nl/z3.html?p=2 的p参数控制分页
2. get请求
2.获取单页源码
1 # -*- coding: utf-8 -*-
2 import requests
3 import time
4 from requests.exceptions import RequestException
5 def get_one_page(page):
6 try:
7 url = "http://hz.ziroom.com/z/nl/z2.html?p=" + str(page)
8 headers = {
9 ‘Referer‘:‘http://hz.ziroom.com/‘,
10 ‘Upgrade-Insecure-Requests‘:‘1‘,
11 ‘User-Agent‘:‘Mozilla/5.0(WindowsNT6.3;Win64;x64)AppleWebKit/537.36(KHTML,likeGecko)Chrome/68.0.3440.106Safari/537.36‘
12 }
13 res = requests.get(url,headers=headers)
14 if res.status_code == 200:
15 print(res.text)
16 except RequestException:
17 return None
18 def main():
19 page = 1
20 get_one_page(page)
21 if __name__ == ‘__main__‘:
22 main()
23 time.sleep(1)
3.解析单页源码
1. 解析html文档, 目的: 测试XPath表达式
将获取的源码保存到当前文件夹下的"result.html"中, 然后通过XPath对其进行相应内容的提取, 当然你也可以使用某些在线工具.
1 from lxml import etree
2 #解析html文档
3 html = etree.parse("./resul.html",etree.HTMLParser())
4 results = html.xpath(‘//ul[@id="houseList"]/li‘)
5 for result in results[1:]:
6 title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) >5 else ""
7 location = result.xpath("./div/h4/a/text()")[0].replace("[","").replace("]",‘‘)
8 area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ","",1) #使用join方法将列表中的内容以" "字符连接
9 nearby = result.xpath("./div/div/p[2]/span/text()")[0]
10 print(title)
11 print(location)
12 print(area)
13 print(nearby)
2. 解析源代码
1 from lxml import etree
2 def parse_one_page(sourcehtml):
3 ‘‘‘解析单页源码‘‘‘
4 contentTree = etree.HTML(sourcehtml) #解析源代码
5 results = contentTree.xpath(‘//ul[@id="houseList"]/li‘) #利用XPath提取相应内容
6 for result in results[1:]:
7 title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) > 5 else ""
8 location = result.xpath("./div/h4/a/text()")[0].replace("[", "").replace("]", ‘‘)
9 area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ", "", 1) # 使用join方法将列表中的内容以" "字符连接
10 nearby = result.xpath("./div/div/p[2]/span/text()")[0]
11 yield {
12 "title": title,
13 "location": location,
14 "area": area,
15 "nearby": nearby
16 }
17 def main():
18 page = 1
19 html = get_one_page(page)
20 print(type(html))
21 parse_one_page(html)
22 for item in parse_one_page(html):
23 print(item)
24
25 if __name__ == ‘__main__‘:
26 main()
27 time.sleep(1)
4.获取多个页面
1 def parse_one_page(sourcehtml):
2 ‘‘‘解析单页源码‘‘‘
3 contentTree = etree.HTML(sourcehtml) #解析源代码
4 results = contentTree.xpath(‘//ul[@id="houseList"]/li‘) #利用XPath提取相应内容
5 for result in results[1:]:
6 title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) > 5 else ""
7 location = result.xpath("./div/h4/a/text()")[0].replace("[", "").replace("]", ‘‘)
8 area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ", "", 1) # 使用join方法将列表中的内容以" "字符连接
9 #nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()这里需要加判断, 改写为下句
10 nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip() if len(result.xpath("./div/div/p[2]/span/text()"))>0 else ""
11 yield {
12 "title": title,
13 "location": location,
14 "area": area,
15 "nearby": nearby
16 }
17 print(nearby)
18 #yield {"pages":pages}
19 def get_pages():
20 """得到总页数"""
21 page = 1
22 html = get_one_page(page)
23 contentTree = etree.HTML(html)
24 pages = int(contentTree.xpath(‘//div[@class="pages"]/span[2]/text()‘)[0].strip("共页"))
25 return pages
26 def main():
27 pages = get_pages()
28 print(pages)
29 for page in range(1,pages+1):
30 html = get_one_page(page)
31 for item in parse_one_page(html):
32 print(item)
33
34 if __name__ == ‘__main__‘:
35 main()
36 time.sleep(1)
5. 存储到MongoDB中
需确保MongoDB已启动服务, 否则必然会存储失败
1 def save_to_mongodb(result):
2 """存储到MongoDB中"""
3 # 创建数据库连接对象, 即连接到本地
4 client = pymongo.MongoClient(host="localhost")
5 # 指定数据库,这里指定ziroom
6 db = client.iroomz
7 # 指定表的名称, 这里指定roominfo
8 db_table = db.roominfo
9 try:
10 #存储到数据库
11 if db_table.insert(result):
12 print("---存储到数据库成功---",result)
13 except Exception:
14 print("---存储到数据库失败---",result)
6.完整代码
1 # -*- coding: utf-8 -*-
2
3 import requests
4 import time
5 import pymongo
6 from lxml import etree
7 from requests.exceptions import RequestException
8 def get_one_page(page):
9 ‘‘‘获取单页源码‘‘‘
10 try:
11 url = "http://hz.ziroom.com/z/nl/z2.html?p=" + str(page)
12 headers = {
13 ‘Referer‘:‘http://hz.ziroom.com/‘,
14 ‘Upgrade-Insecure-Requests‘:‘1‘,
15 ‘User-Agent‘:‘Mozilla/5.0(WindowsNT6.3;Win64;x64)AppleWebKit/537.36(KHTML,likeGecko)Chrome/68.0.3440.106Safari/537.36‘
16 }
17 res = requests.get(url,headers=headers)
18 if res.status_code == 200:
19 return res.text
20 return None
21 except RequestException:
22 return None
23 def parse_one_page(sourcehtml):
24 ‘‘‘解析单页源码‘‘‘
25 contentTree = etree.HTML(sourcehtml) #解析源代码
26 results = contentTree.xpath(‘//ul[@id="houseList"]/li‘) #利用XPath提取相应内容
27 for result in results[1:]:
28 title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) > 5 else ""
29 location = result.xpath("./div/h4/a/text()")[0].replace("[", "").replace("]", ‘‘)
30 area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ", "", 1) # 使用join方法将列表中的内容以" "字符连接
31 #nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()这里需要加判断, 改写为下句
32 nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip() if len(result.xpath("./div/div/p[2]/span/text()"))>0 else ""
33 data = {
34 "title": title,
35 "location": location,
36 "area": area,
37 "nearby": nearby
38 }
39 save_to_mongodb(data)
40 #yield {"pages":pages}
41 def get_pages():
42 """得到总页数"""
43 page = 1
44 html = get_one_page(page)
45 contentTree = etree.HTML(html)
46 pages = int(contentTree.xpath(‘//div[@class="pages"]/span[2]/text()‘)[0].strip("共页"))
47 return pages
48 def save_to_mongodb(result):
49 """存储到MongoDB中"""
50 # 创建数据库连接对象, 即连接到本地
51 client = pymongo.MongoClient(host="localhost")
52 # 指定数据库,这里指定ziroom
53 db = client.iroomz
54 # 指定表的名称, 这里指定roominfo
55 db_table = db.roominfo
56 try:
57 #存储到数据库
58 if db_table.insert(result):
59 print("---存储到数据库成功---",result)
60 except Exception:
61 print("---存储到数据库失败---",result)
62
63 def main():
64 pages = get_pages()
65 print(pages)
66 for page in range(1,pages+1):
67 html = get_one_page(page)
68 parse_one_page(html)
69
70 if __name__ == ‘__main__‘:
71 main()
72 time.sleep(1)
点击查看
7.最终结果
总结
1. 在第三步中XPath使用注意事项
title = result.xpath("./div/h3/a/text()")
此处的点‘.‘不能忘记, 它表示当前节点, 如果不加‘.‘, ‘/‘就表示从根节点开始选取
2. 在第四步获取多个页面时出现索引超出范围错误
nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()
IndexError: list index out of range
造成这种错误原因有两种:
1) [index] index超出list范围
2) [index] index索引内容为空
因为这里的nearby的index是0, 排除第一种情况, 那么这里就是空行了, 加句if判断就可以解决
nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()
#改写以后:
nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip() if len(result.xpath("./div/div/p[2]/span/text()"))>0 else ""
以上主要是对爬虫过程学习的总结, 若有不对的地方, 还请指正, 谢谢!
因还在学习中, 价格部分会用到图片识别, 有待完善.
原文地址：https://www.cnblogs.com/star-zhao/p/9637588.html
时间： 2024-10-11 06:08:37