[[toc]]
一、常用库
- requests 做请求的时候用到: requests.get("url")
- selenium 自动化会用到
- lxml
- beautifulsoup
- pyquery 网页解析库，语法和jquery非常像
- pymysql 存储库,操作mysql数据的
- pymongo 操作MongoDB 数据库
- redis 非关系型数据库
- jupyter 在线记事本
二、什么是Urllib
Python内置的Http请求库
urllib.request 请求模块 模拟浏览器发送请求
urllib.error 异常处理模块
urllib.parse url解析模块 工具模块，如：拆分、合并
urllib.robotparser robots.txt 解析模块
python2 和 python3 的区别
Python2:
import urllib2
response = urllib2.urlopen('http://www.baidu.com');
Python3
import urllib.request
response =urllib.request.urlopen('http://www.baidu.com');
用法：
# urlOpen 发送请求给服务器。
urllib.request.urlopen(url,data=None[参数],[timeout,]*,cafile=None,capath=None,cadefault=false,context=None)
例子：
# 例1：
import urllib.requests
response=urllib.reqeust.urlopen('http://www.baidu.com')
print(response.read().decode('utf-8'))
# 例2：
import urllib.request
import urllib.parse
data=bytes(urllib.parse.urlencode({'word':'hello'}),encoding='utf8')
response=urllib.reqeust.urlopen('http://httpbin.org/post',data=data)
print(response.read())
# 注：加data就是post发送，不加就是以get发送。
# 例3：
# 超时测试
import urllib.request
response =urllib.request.urlopen('http://httpbin.org/get',timeout=1)
print(response.read())
# -----正常
import socket
import urllib.reqeust
import urllib.error
try:
response=urllib.request.urlopen('http://httpbin.org/get',timeout=0.1)
except urllib.error.URLError as e:
if isinstance(e.reason,socket.timeout):
print('TIME OUT')
# 这是就是输出 TIME OUT
响应类型
import urllib.request
response=urllib.request.urlopen('https://www.python.org')
print(type(response))
输出:print(type(response))
状态码、响应头
import urllib.request
response = urllib.request.urlopen('http://www.python.org')
print(response.status) // 正确返回200
print(response.getheaders()) //返回请求头
print(response.getheader('Server'))
三、Request 可以添加headers
import urllib.request
request=urllib.request.Request('https://python.org')
response=urllib.request.urlopen(request)
print(response.read().decode('utf-8'))
例子：
from urllib import request,parse
url='http://httpbin.org/post'
headers={
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.75 Safari/537.36
Host:httpbin.org
}
dict={
'name':'Germey'
}
data=bytes(parse.urlencode(dict),encoding='utf8')
req= request.Request(url=url,data=data,headers=headers,method='POST')
response = request.urlopen(req)
print(response.read().decode('utf-8'))
四、代理
import urllib.request
proxy_handler =urllib.request.ProxyHandler({
'http':'http://127.0.0.1:9743',
'https':'http://127.0.0.1:9743',
})
opener =urllib.request.build_opener(proxy_handler)
response= opener.open('http://httpbin.org/get')
print(response.read())
五、Cookie
import http.cookiejar,urllib.request
cookie = http.cookiejar.Cookiejar()
handler=urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open('http://www.baidu.com')
for item in cookie:
print(item.name+"="+item.value)
第一种保存cookie方式
import http.cookiejar,urllib.request
filename = 'cookie.txt'
cookie =http.cookiejar.MozillaCookieJar(filename)
handler= urllib.request.HTTPCookieProcessor(cookie)
opener=urllib.request.build_opener(handler)
response= opener.open('http://www.baidu.com')
cookie.save(ignore_discard=True,ignore_expires=True)
第二种保存cookie方式
import http.cookiejar,urllib.request
filename = 'cookie.txt'
cookie =http.cookiejar.LWPCookieJar(filename)
handler=urllib.request.HTTPCookieProcessor(cookie)
opener=urllib.request.build_opener(handler)
response=opener.open('http://www.baidu.com')
cookie.save(ignore_discard=True,ignore_expires=True)
读取cookie
import http.cookiejar,urllib.request
cookie=http.cookiejar.LWPCookieJar()
cookie.load('cookie.txt',ignore_discard=True,ignore_expires=True)
handler=urllib.request.HTTPCookieProcessor(cookie)
opener=urllib.request.build_opener(handler)
response=opener.open('http://www.baidu.com')
print(response.read().decode('utf-8'))
六、异常处理
# 例1：
from urllib import reqeust,error
try:
response =request.urlopen('http://cuiqingcai.com/index.htm')
except error.URLError as e:
print(e.reason) # url异常捕获
# 例2:
from urllib import reqeust,error
try:
response =request.urlopen('http://cuiqingcai.com/index.htm')
except error.HTTPError as e:
print(e.reason,e.code,e.headers,sep='\n') # url异常捕获
except error.URLError as e:
print(e.reason)
else:
print('Request Successfully')
七、URL解析
urlparse # url 拆分
urllib.parse.urlparse(urlstring,scheme='',allow_fragments=True)
# 例1：
from urllib.parse import urlparse # url 拆分
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment')
print(type(result),result)
# 例2：
from urllib.parse import urlparse # 没有http
result = urlparse('www.baidu.com/index.html;user?id=5#comment',scheme='https')
print(result)
# 例3：
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment',scheme='https')
print(result)
例4：
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment',allow_fragments=False)
print(result)
# 例5：
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html#comment',allow_fragments=False)
print(result)
拼接：urlunparse
例子：
from urllib.parse import urlunparse
data=['http','www.baidu.com','index.html','user','a=6','comment']
print(urlunparse(data))
urljoin
from urllib.parse import urljoin
print(urljoin('http://www.baidu.com','FAQ.html'))
# 后面覆盖前面的
urlencode
from urllib.parse import urlencode
params={
'name':'gemey',
'age':22
}
base_url='http//www.baidu.com?'
url = base_url+urlencode(params)
print(url)
http://www.baidu.com?name=gemey&age=22
example:
urllib是Python自带的标准库，无需安装，直接可以用。
提供了如下功能：
网页请求
响应获取
代理和cookie设置
异常处理
URL解析
爬虫所需要的功能，基本上在urllib中都能找到，学习这个标准库，可以更加深入的理解后面更加便利的requests库。
urllib库
urlopen 语法
urllib.request.urlopen(url,data=None,[timeout,]*,cafile=None,capath=None,cadefault=False,context=None)
# url:访问的网址
# data:额外的数据，如header，form data
# 用法:
# request:GET
import urllib.request
response = urllib.request.urlopen('http://www.baidu.com')
print(response.read().decode('utf-8'))
# request: POST
# http测试：http://httpbin.org/
import urllib.parse
import urllib.request
data = bytes(urllib.parse.urlencode({'word':'hello'}),encoding='utf8')
response = urllib.request.urlopen('http://httpbin.org/post',data=data)
print(response.read())
# 超时设置
import urllib.request
response = urllib.request.urlopen('http://httpbin.org/get',timeout=1)
print(response.read())
import socket
import urllib.request
import urllib.error
try:
response = urllib.request.urlopen('http://httpbin.org/get',timeout=0.1)
except urllib.error.URLError as e:
if isinstance(e.reason,socket.timeout):
print('TIME OUT')
解析
# 主要是一个工具模块，可用于为爬虫提供URL。
# urlparse:拆分URL
urlib.parse.urlparse(urlstring,scheme='', allow_fragments=True)
# scheme: 协议类型
# 是否忽略'#'部分
# 举个例子
from urllib import urlparse
result = urlparse("https://edu.hellobi.com/course/157/play/lesson/2580")
result
##ParseResult(scheme='https', netloc='edu.hellobi.com', path='/course/157/play/lesson/2580', params='', query='', fragment='')
urlunparse:拼接URL，为urlparse的反向操作
from urllib.parse import urlunparse
data = ['http','www.baidu.com','index.html','user','a=6','comment']
print(urlunparse(data))
# urljoin:拼接两个URL
# urljoin
# urlencode:字典对象转换成GET请求对象
from urllib.parse import urlencode
params = {
'name':'germey',
'age': 22
}
base_url = 'http://www.baidu.com?'
url = base_url + urlencode(params)
print(url)
八、响应
# 响应类型
import urllib.open
response = urllib.request.urlopen('https:///www.python.org')
print(type(response))
# 状态码， 响应头
import urllib.request
response = urllib.request.urlopen('https://www.python.org')
print(response.status)
print(response.getheaders())
print(response.getheader('Server'))
Request
声明一个request对象，该对象可以包括header等信息，然后用urlopen打开。
# 简单例子
import urllib.request
request = urllib.request.Requests('https://python.org')
response = urllib.request.urlopen(request)
print(response.read().decode('utf-8'))
# 增加header
from urllib import request, parse
url = 'http://httpbin.org/post'
headers = {
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36'
'Host':'httpbin.org'
}
# 构造POST表格
dict = {
'name':'Germey'
}
data = bytes(parse.urlencode(dict),encoding='utf8')
req = request.Request(url=url,data=data,headers=headers,method='POST')
response = request.urlopen(req)
print(response.read()).decode('utf-8')
# 或者随后增加header
from urllib import request, parse
url = 'http://httpbin.org/post'
dict = {
'name':'Germey'
}
req = request.Request(url=url,data=data,method='POST')
req.add_hader('User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36')
response = request.urlopen(req)
print(response.read().decode('utf-8'))
九、代理
import urllib.request
proxy_handler = urllib.request.ProxyHandler({
'http':'http://127.0.0.1:9743'
'https':'https://127.0.0.1.9743'
})
opener = urllib.request.build_openner(proxy_handler)
response = opener.open('http://www.baidu.com')
print(response.read())
Cookie:客户端用于记录用户身份,维持登录信息
import http.cookiejar, urllib.request
cookie = http.cookiejar.CookieJar()
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
for item in cookie:
print(item.name+"="+item.value)
# 保存cooki为文本
import http.cookiejar, urllib.request
filename = "cookie.txt"
# 保存类型有很多种
# 类型1
cookie = http.cookiejar.MozillaCookieJar(filename)
# 类型2
cookie = http.cookiejar.LWPCookieJar(filename)
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
# 使用相应的方法读取
import http.cookiejar, urllib.request
cookie = http.cookiejar.LWPCookieJar()
cookie.load('cookie.txt',ignore_discard=True,ignore_expires=True)
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
十、异常处理
# 捕获异常，保证程序稳定运行
# 访问不存在的页面
from urllib import request, error
try:
response = request.urlopen('http://cuiqingcai.com/index.htm')
except error.URLError as e:
print(e.reason)
# 先捕获子类错误
from urllib imort request, error
try:
response = request.urlopen('http://cuiqingcai.com/index.htm')
except error.HTTPError as e:
print(e.reason, e.code, e.headers, sep='\n')
except error.URLError as e:
print(e.reason)
else:
print("Request Successfully")
# 判断原因
import socket
import urllib.request
import urllib.error
try:
response = urllib.request.urlopen('http://httpbin.org/get',timeout=0.1)
except urllib.error.URLError as e:
if isinstance(e.reason,socket.timeout):
print('TIME OUT')
