爬虫学习：request+xpath爬取笔趣阁小说

爬虫入坑一段时间了，准备搞点事，嘿嘿

注意：阅读本文要有一定的python基础，了解Requests和Xpath相关语法，以及正则表达式

1.关于Requests和Xpath

Requests

Requests是用python语言基于urllib编写的，采用的是Apache2 Licensed开源协议的HTTP库
如果你看过文章关于urllib库的使用，你会发现，其实urllib还是非常不方便的，而Requests它会比urllib更加方便，可以节约我们大量的工作。（用了requests之后，你基本都不愿意用urllib了）一句话，requests是python实现的最简单易用的HTTP库，建议爬虫使用requests库。

Xpath

XPath即为 XML路径语言（XML Path Language），它是一种用来确定XML文档中某部分位置的语言。

XPath基于XML的树状结构，提供在数据结构树中找寻节点的能力。起初XPath的提出的初衷是将其作为一个通用的、介于 XPointer与 XSL间的语法模型。但是XPath很快的被开发者采用来当作小型查询语言。

2.代码

#正则+request+xpath
from lxml import etree
import requests
import re
import warnings
import time

warnings.filterwarnings("ignore")
headers = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1 Trident/5.0;"}

def get_urls(URL):
    Html=requests.get(URL,headers=headers,verify=False)
    Html.encoding = 'gbk'
    HTML=etree.HTML(Html.text)
    results=HTML.xpath('//dd/a/@href')
    return results

def get_items(result):
    url='https://www.biquyun.com'+str(result)
    html=requests.get(url,headers=headers,verify=False)
    html.encoding = 'gbk'
    pattern=re.compile('<div.*?<h1>(.*?)</h1>.*?<div.*?content">(.*?)</div>',re.S)
    items='\n'*2+str(re.findall(pattern,html.text)[0][0])+'\n'*2+str(re.findall(pattern,html.text)[0][1])
    items=items.replace('&nbsp;&nbsp;&nbsp;&nbsp;','').replace('<br />','')
    return items
    
def save_to_file(items):
    with open ("xiaoshuo1.txt",'a',encoding='utf-8') as file:
        file.write(items)    
    
def main(URL):
    results=get_urls(URL)
    ii=1
    for result in results:
        items=get_items(result)
        save_to_file(items)
        print(str(ii)+' in 1028')
        ii=ii+1
#        time.sleep(1)
if __name__ == '__main__':
    start_1 = time.time()
    URL='https://www.biquyun.com/15_15566/'
    main(URL)
    print('Done!')
    end_1 = time.time()
    print('爬虫时间1:',end_1-start_1)

运行结果：

#requests+xpath
from lxml import etree
import requests
import re
import warnings
import time

warnings.filterwarnings("ignore")#由于requests获取网页源代码采用verify=False，需要忽略警告
headers = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1 Trident/5.0;"}

def get_urls(URL):
    Html=requests.get(URL,headers=headers,verify=False)
    Html.encoding = 'gbk'
    HTML=etree.HTML(Html.text)
    results=HTML.xpath('//dd/a/@href')
    return results

def get_items(result):
    url='https://www.biquyun.com'+str(result)
    html=requests.get(url,headers=headers,verify=False)
    html.encoding = 'gbk'
    html=etree.HTML(html.text)
    resultstitle=html.xpath('//*[@class="bookname"]/h1/text()')
    resultsbody=html.xpath('//*[@id="content"]/text()')
    items=str(resultstitle[0])+'\n'*2+str(resultsbody).replace('\', \'','').replace('\\xa0\\xa0\\xa0\\xa0','').replace('\\r\\n\\r\\n','\n\n').replace('[\'','').replace('\']','')+'\n'*2
    return items

def save_to_file(items):
    with open ("xiaoshuo2.txt",'a',encoding='utf-8') as file:
        file.write(items)    
    
def main(URL):
    results=get_urls(URL)
    ii=1
    for result in results:
        items=get_items(result)
        save_to_file(items)
        print(str(ii)+' in 1028')
        ii=ii+1
#        time.sleep(1)
if __name__ == '__main__':
    start_2 = time.time()
    URL='https://www.biquyun.com/15_15566/'
    main(URL)
    print('Done!')
    end_2 = time.time()
    print('爬虫时间2:',end_2-start_2)

运行结果：

ps：具体爬取速度与电脑配置和网速有关。另外，利用正则匹配时间有时候会很长，建议采用xpath。

编写爬虫的坑：

1.爬取网页中文乱码

解决方案：

print(response.encoding)  # requests猜测的编码格式
print(requests.utils.get_encodings_from_content(response.text)[0])

参考链接：

http://cn.python-requests.org/zh_CN/latest/

https://www.liaoxuefeng.com/wiki/1016959663602400/1183249464292448

http://www.w3school.com.cn/xpath/index.asp

https://www.cnblogs.com/lei0213/p/7506130.html

https://blog.csdn.net/ahua_c/article/details/80942726

https://www.bilibili.com/video/av19057145

https://www.crifan.com/python_re_search_vs_re_findall/

https://www.jianshu.com/p/4c076da1b7f7

https://blog.csdn.net/u014109807/article/details/79735400

https://www.cnblogs.com/bjdx1314/p/8934031.html

https://www.cnblogs.com/ConnorShip/p/9966290.html

https://www.cnblogs.com/carlos-mm/p/8819519.html

https://blog.51cto.com/13603552/2308728

https://blog.csdn.net/sinat_35360663/article/details/78455991

https://www.cnblogs.com/lei0213/p/7506130.html

来源：oschina

链接：https://my.oschina.net/u/4386657/blog/3477455

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