Python常用爬虫代码总结方便查询
beautifulsoup解析页面
from bs4 import BeautifulSoup
soup = BeautifulSoup(htmltxt, "lxml")
# 三种装载器
soup = BeautifulSoup("<a></p>", "html.parser")
### 只有起始标签的会自动补全，只有结束标签的会自动忽略
### 结果为：<a></a>
soup = BeautifulSoup("<a></p>", "lxml")
### 结果为：<html><body><a></a></body></html>
soup = BeautifulSoup("<a></p>", "html5lib")
### html5lib则出现一般的标签都会自动补全
### 结果为：<html><head></head><body><a><p></p></a></body></html>
# 根据标签名、id、class、属性等查找标签
### 根据class、id、以及属性alog-action的值和标签类别查询
soup.find("a",class_="title",id="t1",attrs={"alog-action": "qb-ask-uname"}))
### 查询标签内某属性的值
pubtime = soup.find("meta",attrs={"itemprop":"datePublished"}).attrs['content']
### 获取所有class为title的标签
for i in soup.find_all(class_="title"):
print(i.get_text())
### 获取特定数量的class为title的标签
for i in soup.find_all(class_="title",limit = 2):
print(i.get_text())
### 获取文本内容时可以指定不同标签之间的分隔符，也可以选择是否去掉前后的空白。
soup = BeautifulSoup('<p class="title" id="p1"><b> The Dormouses story </b></p><p class="title" id="p1"><b>The Dormouses story</b></p>', "html5lib")
soup.find(class_="title").get_text("|", strip=True)
#结果为：The Dormouses story|The Dormouses story
### 获取class为title的p标签的id
soup.find(class_="title").get("id")
### 对class名称正则：
soup.find_all(class_=re.compile("tit"))
### recursive参数，recursive=False时，只find当前标签的第一级子标签的数据
soup = BeautifulSoup('<html><head><title>abc','lxml')
soup.html.find_all("title", recursive=False)
unicode编码转中文
content = "\u65f6\u75c7\u5b85"
content = content.encode("utf8","ignore").decode('unicode_escape')
url encode的解码与解码
from urllib import parse # 编码 x = "中国你好" y = parse.quote(x) print(y) # 解码 x = parse.unquote(y) print(x)
html转义字符的解码
from html.parser import HTMLParser htmls = "<div><p>" txt = HTMLParser().unescape(htmls) print(txt) . # 输出<div><p>
base64的编码与解码
import base64
# 编码
content = "测试转码文本123"
contents_base64 = base64.b64encode(content.encode('utf-8','ignore')).decode("utf-8")
# 解码
contents = base64.b64decode(contents_base64)
过滤emoji表情
def filter_emoji(desstr,restr=''):
try:
co = re.compile(u'[\U00010000-\U0010ffff]')
except re.error:
co = re.compile(u'[\uD800-\uDBFF][\uDC00-\uDFFF]')
return co.sub(restr, desstr)
完全过滤script和style标签
import requests from bs4 import BeautifulSoup soup = BeautifulSoup(htmls, "lxml") for script in soup(["script", "style"]): script.extract() print(soup)
过滤html的标签，但保留标签里的内容
import re
htmls = "<p>abc</p>"
dr = re.compile(r'<[^>]+>',re.S)
htmls2 = dr.sub('',htmls)
print(htmls2) #abc
正则提取内容（一般处理json）
rollback({
"response": {
"code": "0",
"msg": "Success",
"dext": ""
},
"data": {
"count": 3,
"page": 1,
"article_info": [{
"title": "“小库里”：适应比赛是首要任务 投篮终会找到节奏",
"url": "http:\/\/sports.qq.com\/a\/20180704\/035378.htm",
"time": "2018-07-04 16:58:36",
"column": "NBA",
"img": "",
"desc": ""
}, {
"title": "首钢体育助力国家冰球集训队 中国冰球联赛年底启动",
"url": "http:\/\/sports.qq.com\/a\/20180704\/034698.htm",
"time": "2018-07-04 16:34:44",
"column": "综合体育",
"img": "",
"desc": ""
}...]
}
})
import re
# 提取这个json中的每条新闻的title、url
# (.*?)为要提取的内容，可以在正则字符串中加入.*？表示中间省略若干字符
reg_str = r'"title":"(.*?)",.*?"url":"(.*?)"'
pattern = re.compile(reg_str,re.DOTALL)
items = re.findall(pattern,htmls)
for i in items:
tilte = i[0]
url = i[1]
时间操作
# 获取当前日期
today = datetime.date.today()
print(today) #2018-07-05
# 获取当前时间并格式化
time_now = time.strftime("%Y-%m-%d %H:%M:%S",time.localtime(time.time()))
print(time_now) #2018-07-05 14:20:55
# 对时间戳格式化
a = 1502691655
time_a = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(int(a)))
print(time_a) #2017-08-14 14:20:55
# 字符串转为datetime类型
str = "2018-07-01 00:00:00"
datetime.datetime.strptime(st, "%Y-%m-%d %H:%M:%S")
# 将时间转化为时间戳
time_line = "2018-07-16 10:38:50"
time_tuple = time.strptime(time_line, "%Y-%m-%d %H:%M:%S")
time_line2 = int(time.mktime(time_tuple))
# 明天的日期
today = datetime.date.today()
tomorrow = today + datetime.timedelta(days=1)
print(tomorrow) #2018-07-06
# 三天前的时间
today = datetime.datetime.today()
tomorrow = today + datetime.timedelta(days=-3)
print(tomorrow) #2018-07-02 13:37:00.107703
# 计算时间差
start = "2018-07-03 00:00:00"
time_now = datetime.datetime.now()
b = datetime.datetime.strptime(start,'%Y-%m-%d %H:%M:%S')
minutes = (time_now-b).seconds/60
days = (time_now-b).days
all_minutes = days*24*60+minutes
print(minutes) #821.7666666666667
print(days) #2
print(all_minutes) #3701.7666666666664
数据库操作
import pymysql conn = pymysql.connect(host='10.0.8.81', port=3306, user='root', passwd='root',db='xxx', charset='utf8') cur = conn.cursor() insert_sql = "insert into tbl_name(id,name,age) values(%s,%s,%s) id = 1 name = "like" age = 26 data_list = [] data = (id,name,age) # 单条插入 cur.execute(insert_sql,data) conn.commit() # 批量插入 data_list.append(data) cur.executemany(insert_sql,data_list) conn.commit() #特殊字符处理(name中含有特殊字符) data = (id,pymysql.escape_string(name),age) #更新 update_sql = "update tbl_name set content = '%s' where id = "+str(id) cur.execute(update_sql%(pymysql.escape_string(content))) conn.commit() #批量更新 update_sql = "UPDATE tbl_recieve SET content = %s ,title = %s , is_spider = %s WHERE id = %s" update_data = (contents,title,is_spider,one_new[0]) update_data_list.append(update_data) if len(update_data_list) > 500: try: cur.executemany(update_sql,update_data_list) conn.commit()
总结
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