一、常用库
1、requests 做请求的时候用到。
requests.get("url")
2、selenium 自动化会用到。
3、lxml
4、beautifulsoup
5、pyquery 网页解析库 说是比beautiful 好用,语法和jquery非常像。
6、pymysql 存储库。操作mysql数据的。
7、pymongo 操作MongoDB 数据库。
8、redis 非关系型数据库。
9、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
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
2和3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:
例子1:
import urllib.requests
response=urllib.reqeust.urlopen('http://www.baidu.com')
print(response.read().decode('utf-8'))
例子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。
例子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
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
例子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
例子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')
7、URL解析
urlparse //url 拆分
urllib.parse.urlparse(urlstring,scheme='',allow_fragments=True)
例子:
from urllib.parse import urlparse //url 拆分
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment')
print(type(result),result)
结果:
例子2:
from urllib.parse import urlparse //没有http
result = urlparse('www.baidu.com/index.html;user?id=5#comment',scheme='https')
print(result)
例子3:
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment',scheme='https')
print(result)
例子4:
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html;user?id=5#comment',allow_fragments=False)
print(result)
例子5:
from urllib.parse import urlparse
result = urlparse('http://www.baidu.com/index.html#comment',allow_fragments=False)
print(result)
七、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')
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'))
Handler:处理更加复杂的页面
官方说明
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")
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')
URL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
![](https://upload-images.jianshu.io/upload_images/2013053-79d80fc9aca76baf.png)
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)
最后还有一个robotparse,解析网站允许爬取的部分。
标签:常用,http,Python,request,爬虫,urllib,print,import,response From: https://www.cnblogs.com/kn-zheng/p/17446164.html