1爬虫解析库的使用

Xpath解析库
使用Xpath解析库需要先安装lxml库
pip3 install lxml
Beautiful Soup解析库
pip3 install beautifulsoup4
还需要安装requests
pip3 install requests

2从js中获取数据

将接口传递给js的数据获取

import re
import json
import requests
# 获取网页
def get_page():
    # 网址
    url = 'http://cd.meituan.com/meishi/b6119/'
    # 伪装请求头
    headers = {
        "User-Agent": "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)"
    }
    # 请求网页并返回响应
    response = requests.get(url, headers=headers)
    if response.status_code == 200:
        return response.content.decode('utf-8')
    return None
def main():
    html = get_page()
    print(html)
    pattern = re.compile('"poiInfos":(.*?)},"comHeader"', re.S)
    result = re.findall(pattern, html)
    print(result)
    meituan = json.loads(result[0])
    print(len(meituan))
    for item in meituan:
        print(item['title'])
if __name__ == '__main__':
    main()

3lxml使用

import requests
import re
from lxml import etree
# 取页面HTML
def get_one_page():
    url = "https://www.douban.com/group/explore"
    headers =  {
        "User-Agent": "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)" 
    }
    response = requests.get(url, headers=headers)
    if response.status_code == 200:
        text = response.content.decode('utf-8')
        return text
    return None
# 解析页面
def parse_with_xpath(html):
    etree_html = etree.HTML(html)
    print(etree_html)
    channel_result = etree_html.xpath('//div[@class="channel-item"]')
    for channel in channel_result:
        title = channel.xpath('./div[@class="bd"]/h3/a/text()')[0]  
        print(title)        
    title_result = etree_html.xpath('//div[@class="channel-item"]/div[@class="bd"]/h3/a/text()')
    print(title_result)
    # 匹配所有节点 //* ; 双斜杠表示从根目录下匹配(即从最开始匹配)，单斜杠表示获取上一个的子节点
    result = etree_html.xpath('//*')
    print(result)
    print(len(result))
    # 匹配所有子节点 //a    文本获取：text()
    result = etree_html.xpath('//a/text()')
    print(result)
    # 查找元素子节点 /
    result = etree_html.xpath('//div/p/text()')
    print(result)
    # 查找元素所有子孙节点 //
    result = etree_html.xpath('//div[@class="channel-item"]')
    print(len(result))
    result = etree_html.xpath('//div[@class="channel-item"] | //span[@class="pubtime"]/../span/a/text()')
    print(result)
    # 父节点 ..
    result = etree_html.xpath('//span[@class="pubtime"]/../span/a/text()')
    print(result)
    # 属性匹配 [@class="xxx"]
    # 文本匹配 text() 获取所有文本//text()
    result = etree_html.xpath('//div[@class="article"]//text()')
    print(result)
    # 属性获取 @href
    result = etree_html.xpath('//div[@class="article"]/div/div/@class')[0]
    print(result)
    result = etree_html.xpath('//div[@class="bd"]/h3/a/@href')
    print(result)
    # 属性多值匹配 contains(@class 'xx')
    result = etree_html.xpath('//div[contains(@class, "grid-16-8")]//div[@class="likes"]/text()[1]')
    print(result)
    # 多属性匹配 or, and, mod, //book | //cd, + - * div = != < > <= >=
    result = etree_html.xpath('//span[@class="pubtime" and contains(text(), "-12-29")]/text()')
    print(result)
    # 按序选择 [1] [last()] [poistion() < 3] [last() -2]
    # 节点轴
    result = etree_html.xpath('//div/child::div[@class="likes"]/following-sibling::*//span[@class="pubtime"]/text()')
    print(result)
    print(len(result))
    //li/ancestor::*  所有祖先节点
    //li/ancestor::div div这个祖先节点
    //li/attribute::* attribute轴，获取li节点所有属性值
    //li/child::a[@href="link1.html"]  child轴，获取直接子节点
    //li/descendant::span 获取所有span类型的子孙节点   
    //li/following::* 选取文档中当前节点的结束标记之后的所有节点
    //li/following-sibling::*     选取当前节点之后的所有同级节点
    result = etree_html.xpath('//div[@class="channel-item"][1]/following-sibling::*')
    print(result)
    print(len(result))      
    result = etree_html.xpath('//div[contains(@class, "channel-group-rec")]//div[@class="title"]/following::*[1]/text()')
    print(result)
def main():
    html = get_one_page()
    print(html)
    parse_with_xpath(html)
if __name__ == '__main__':
    main()

channel_result = etree_html.xpath('//div[@class="channel-item"]') 获取div中class属性为channel-item的节点
channel_result = etree_html.xpath('//div[@class="channel-item"]/text()') 获取div中class属性为channel-item的节点的文本内容(不包括属性)
channel_result = etree_html.xpath('//div[@class="channel-item"]//text()') 获取div中class属性为channel-item的节点的文本内容(包括属性)
双斜杠表示从当前目录下匹配;单斜杠text()表示获取标签中的文本内容;//text()表示获取所有文本(包括属性)
/表示该标签下的子标签;//标签该标签下的所有标签;./表示从当前标签取其子标签;.//表示从当前标签取其所有标签
result = etree_html.xpath('//div[@class="bd"]/h3/a/@href') 获取属性
| 表示并，一下取多个内容；
按序选择 [1]第一个 [last()]最后一个 [poistion() < 3]前两个 [last() -2]倒数第三个

4beautifulsoup使用

from bs4 import BeautifulSoup
import requests
import re
# 取页面HTML
def get_one_page():
    url = "http://sports.sina.com.cn/nba/"
    headers =  {
        "User-Agent": "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b13pre) Gecko/20110307 Firefox/4.0b13pre" 
    }
    response = requests.get(url, headers=headers)
    if response.status_code == 200:
        text = response.content.decode('utf-8')
        return text
    return None
def parse_with_bs4(html):
    # html = '<p><div><a></a></div></p>'
    # print(html)
    soup = BeautifulSoup(html, 'lxml')      
    # 让页面标签整齐的输出
    print(soup.prettify())
    # head标签里面title的文字内容
    print(soup.title.string)
    # 取整个指定的标签
    print(soup.head)
    print(type(soup.head))
    print(soup.p)
    print(soup.p.name)
    print(soup.img.attrs["src"])
    print(soup.img.attrs)
    print(soup.img.attrs['src'])
    print(soup.img['src'])
    print(soup.p)
    print(soup.p.contents) # 取p节点下面所有子节点列表
    print(soup.p.descendants) # 取p节点所有子孙节点
    # 取a的所有祖先节点
    # [0]表示取它的父标签，1表示在往上取一层
    print(soup.a.parent) # 取父节点
    print(soup.a.parents) # 取所有祖先节点
    print(list(soup.a.parents)) # 取父节点
    print(list(soup.a.parents)[0].attrs['class'])
    print(soup.head.title.string)
    result = soup.select('.news-list-b .list .item p a')
    for item in result:
        print(item.string)
        print(item['href'])
    result = soup.select('.-live-layout-row.layout_sports_350_650')
    print(result)
    l = soup.select('.ct_t_01 a')
    for item in l:
        print(item.string)
        print(item['href'])
    print(len(l))
    item = soup.select('#syncad_1 p')[0]
    print(item)
    print(item.contents)
    print(len(item.contents))
    item = soup.select('.b_time')[0].string
    print(item)
def main():
    html = get_one_page()
    # print(html)
    parse_with_bs4(html)
if __name__ == '__main__':
    main()

soup = BeautifulSoup(html, 'lxml');生成soup对象；
soup.prettify()对传入的html参数进行全部
soup.title.string 获取title中的文本内容；soup.head获取head标签及其中的内容
soup.p.name 获取p标签的标签名(此处为p)；soup.img['src']获取img中的src属性
soup.p.contents 取p节点下面所有子节点列表；
soup.p.descendants 取p节点所有子孙节点；soup.a.parent 取父节点；soup.a.parents 取所有祖先节点；list(soup.a.parents)[0].attrs['class']； [0]表示取它的父标签，1表示在往上取一层

result = soup.select('.news-list-b .list .item p a')
for item in result:
    print(item.string)
    print(item['href'])

获取对应class下的a标签并输出其文本内容及其href属性。
result = soup.select('.-live-layout-row.layout_sports_350_650')

5将数据存至数据库

5.1建表语句

create database maoyan default character set='utf8';
use maoyan;
create table movie (
  id int primary key auto_increment,
  title varchar(256),
  actor varchar(256),
  detail varchar(1024),
  cover_url varchar(1024)
);

5.2存数据相关函数

import pymysql
# 获取数据库连接
def get_connection():
    host = '127.0.0.1'
    port = 3306
    user = 'root'
    password = '123456'
    database = 'maoyan'
    db = pymysql.connect(host, user, password, database, charset='utf8', port=port)
    return db
# 获取数据库游标
def get_cursor(db):
    cursor = db.cursor()
    return cursor
# 关闭链接
def close_connection(db):
    db.colos()
# 插入一条记录
def insert_record(db, cursor, item):
    sql = 'insert into movie (title, actor, detail, cover_url) values("%s","%s","%s","%s")' % (item['movie_name'], item['actor'], item['detail'], item['cover'])
    print(sql)
    cursor.execute(sql)
    # 需要上传，数据才能存入数据库
    db.commit()

5.3爬虫中存数据

from maoyan_db_helper import *
db = get_connection()
cursor = get_cursor(db)
for i in range(len(details)):
    simple_message = {}
    simple_message['cover'] = covers[i]
    insert_record(db, cursor, simple_message)