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前言

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作者： Star_Zhao

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本次爬取自如網房源信息所用到的知識點:

requests get請求
lxml解析html
Xpath
MongoDB存儲

正文

分析目標站點

url: http://hz.ziroom.com/z/nl/z3.html?p=2 的p參數控制分頁
get請求

獲取單頁源碼

# -*- coding: utf-8 -*-
import requests
import timefrom requests.exceptions import RequestException
def get_one_page(page):    try:
        url = "http://hz.ziroom.com/z/nl/z2.html?p=" + str(page)
        headers = {            'Referer':'http://hz.ziroom.com/',
            'Upgrade-Insecure-Requests':'1',
            'User-Agent':'Mozilla/5.0(windowsNT6.3;Win64;x64)AppleWebKit/537.36(KHTML,likeGecko)Chrome/68.0.3440.106Safari/537.36'
        }        res = requests.get(url,headers=headers)
        if res.status_code == 200:
            print(res.text)    except RequestException:        return None
def main():    page = 1
    get_one_page(page)if __name__ == '__main__':
    main()    time.sleep(1)

解析單頁源碼

解析html文檔, 目的: 測試XPath表達式

將獲取的源碼保存到當前文件夾下的"result.html"中, 然后通過XPath對其進行相應內容的提取, 當然你也可以使用某些在線工具.

from lxml import etree
#解析html文檔html = etree.parse("./resul.html",etree.HTMLParser())results = html.xpath('//ul[@id="houseList"]/li')
for result in results[1:]:
    title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) >5 else ""
    location = result.xpath("./div/h4/a/text()")[0].replace("[","").replace("]",'')    area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ","",1) #使用join方法將列表中的內容以" "字符連接    nearby = result.xpath("./div/div/p[2]/span/text()")[0]    print(title)    print(location)    print(area)    print(nearby)

解析源代碼

from lxml import etree
def parse_one_page(sourcehtml):
    '''解析單頁源碼'''    contentTree = etree.HTML(sourcehtml)   #解析源代碼    results = contentTree.xpath('//ul[@id="houseList"]/li') #利用XPath提取相應內容
    for result in results[1:]:
        title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) > 5 else ""
        location = result.xpath("./div/h4/a/text()")[0].replace("[", "").replace("]", '')        area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ", "", 1)  # 使用join方法將列表中的內容以" "字符連接        nearby = result.xpath("./div/div/p[2]/span/text()")[0]        yield {        "title": title,        "location": location,        "area": area,        "nearby": nearby        }def main():    page = 1    html = get_one_page(page)
    print(type(html))    parse_one_page(html)
    for item in parse_one_page(html):
      print(item)if __name__ == '__main__':
    main()    time.sleep(1)

獲取多個頁面

def parse_one_page(sourcehtml):
    '''解析單頁源碼'''
    contentTree = etree.HTML(sourcehtml)   #解析源代碼    results = contentTree.xpath('//ul[@id="houseList"]/li') #利用XPath提取相應內容
    for result in results[1:]:
        title = result.xpath("./div/h3/a/text()")[0][5:] if len(result.xpath("./div/h3/a/text()")[0]) > 5 else ""
        location = result.xpath("./div/h4/a/text()")[0].replace("[", "").replace("]", '')
        area = " ".join(result.xpath("./div/div/p[1]/span/text()")).replace(" ", "", 1)  # 使用join方法將列表中的內容以" "字符連接
        #nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()這里需要加判斷, 改寫為下句
        nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip() if len(result.xpath("./div/div/p[2]/span/text()"))>0 else ""
        yield {
        "title": title,
        "location": location,
        "area": area,
        "nearby": nearby
        }        print(nearby)
    #yield {"pages":pages}
def get_pages():    """得到總頁數"""
    page = 1
    html = get_one_page(page)    contentTree = etree.HTML(html)    pages = int(contentTree.xpath('//div[@class="pages"]/span[2]/text()')[0].strip("共頁"))
    return pages
def main():    pages = get_pages()    print(pages)
    for page in range(1,pages+1):
        html = get_one_page(page)        for item in parse_one_page(html):
            print(item)
if __name__ == '__main__':
    main()    time.sleep(1)

存儲到MongoDB中

需確保MongoDB已啟動服務, 否則必然會存儲失敗

def save_to_mongodb(result):
    """存儲到MongoDB中"""
    # 創(chuàng)建數據庫連接對象, 即連接到本地
    client = pymongo.MongoClient(host="localhost")
    # 指定數據庫,這里指定ziroom
    db = client.iroomz
    # 指定表的名稱, 這里指定roominfo
    db_table = db.roominfo
    try:
        #存儲到數據庫
        if db_table.insert(result):
            print("---存儲到數據庫成功---",result)
    except Exception:
        print("---存儲到數據庫失敗---",result)

完整代碼

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     '''獲取單頁源碼'''
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     '''解析單頁源碼'''
25     contentTree = etree.HTML(sourcehtml)   #解析源代碼
26     results = contentTree.xpath('//ul[@id="houseList"]/li') #利用XPath提取相應內容
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方法將列表中的內容以" "字符連接
31         #nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()這里需要加判斷, 改寫為下句
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     """得到總頁數"""
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("共頁"))
47     return pages
48 def save_to_mongodb(result):49     """存儲到MongoDB中"""
50     # 創(chuàng)建數據庫連接對象, 即連接到本地
51     client = pymongo.MongoClient(host="localhost")
52     # 指定數據庫,這里指定ziroom
53     db = client.iroomz54     # 指定表的名稱, 這里指定roominfo55     db_table = db.roominfo56     try:57         #存儲到數據庫
58         if db_table.insert(result):
59             print("---存儲到數據庫成功---",result)
60     except Exception:
61         print("---存儲到數據庫失敗---",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)

最終結果

總結

在第三步中XPath使用注意事項

title = result.xpath("./div/h3/a/text()")
此處的點'.'不能忘記, 它表示當前節(jié)點, 如果不加'.', '/'就表示從根節(jié)點開始選取

在第四步獲取多個頁面時出現索引超出范圍錯誤

nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()
IndexError: list index out of range

造成這種錯誤原因有兩種:

[index] index超出list范圍
[index] index索引內容為空

因為這里的nearby的index是0, 排除第一種情況, 那么這里就是空行了, 加句if判斷就可以解決

nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip()
#改寫以后:nearby = result.xpath("./div/div/p[2]/span/text()")[0].strip() if len(result.xpath("./div/div/p[2]/span/text()"))>0 else ""

以上主要是對爬蟲過程學習的總結, 若有不對的地方, 還請指正, 謝謝!