爬虫:Urllib库详解

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什么是Urllib:

python内置的HTTP请求库

urllib.request : 请求模块

urllib.error : 异常处理模块

urllib.parse: url解析模块

urllib.robotparser  : robots.txt解析模块

    GET请求方式
    POST请求方式
    超时timeout,异常处理
    响应类型(响应码,响应头...)
    POST请求添加Headers
    代理方法
    cookie添加 读取
    ---------- parse 包下 -----------
    urlparse 解析网址
    urlunparse 拼接网址
    urlencode GET参数化(比较有用)

 

python3:

urlopen

# urllib参数
urllib.request.urlopen(url, data=None, [timeout, ]*, cafile=None, capath=None, cadefault=False, context=None) 
# url  post数据  超时

#############################
import urllib.request

# GET方式(不加data)
response = urllib.request.urlopen(http://www.baidu.com) # 请求数据
print(response.read().decode(utf-8)) # 转换为字符串编码,read()得到的是byte格式的
#############################
import urllib.parse
import urllib.request

# POST方式(加data)
data = bytes(urllib.parse.urlencode({word: hello}), encoding=utf8)
response = urllib.request.urlopen(http://httpbin.org/post, data=data)  # http://httpbin.org/post 用来做HTTP测试的网址
print(response.read())
#############################
import urllib.request

#超时设置
response = urllib.request.urlopen(http://httpbin.org/get, timeout=1)
print(response.read())
##############################

响应

# 响应类型
import urllib.request

response = urllib.request.urlopen(https://www.python.org)
print(type(response)) #<class ‘http.client.HTTPResponse‘>

#############################
# 状态码、响应头
import urllib.request

response = urllib.request.urlopen(https://www.python.org)
print(response.status) #获取状态码
print(response.getheaders()) # 获取响应头
print(response.getheader(Server)) # 响应的服务
#############################
import urllib.request
#获取响应内容
response = urllib.request.urlopen(https://www.python.org)
print(response.read().decode(utf-8)) # read() 获取bytes类型

Request

# 加入headers,发送一个POST请求
from urllib import request, parse

url = http://httpbin.org/post
headers = {
    User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows NT),
    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))

Handler

# 添加代理
import urllib.request

proxy_handler = urllib.request.ProxyHandler({ # 代理设置
    http: http://127.0.0.1:9743,
    https: https://127.0.0.1:9742
})
opener = urllib.request.build_opener(proxy_handler)
response = opener.open(http://httpbin.org/get)
print(response.read())

Cookie

import http.cookiejar, urllib.request

# 获取cookies
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)
#############################

# 将cookie保存为txt文件
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文件
import http.cookiejar, urllib.request
# 用哪种格式存cookies,就用哪种方法读取
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))

异常处理

# 异常处理1
from urllib import request, error
try:
    response = request.urlopen(http://cuiqingcai.com/index.htm)
except error.URLError as e:
    print(e.reason)

#############################
# 异常处理2
from urllib import 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)
#############################
# 异常处理3
import socket
import urllib.request
import urllib.error

try:
    response = urllib.request.urlopen(https://www.baidu.com, timeout=0.01)
except urllib.error.URLError as e:
    print(type(e.reason))
    if isinstance(e.reason, socket.timeout):
        print(TIME OUT)

URL解析

# 一个参数
from urllib.parse import urlparse
result = urlparse(http://www.baidu.com/index.html;user?id=5#comment)
print(type(result), result)

##########################
# 指定协议, 如果没有取https, 有就用url带的
from urllib.parse import urlparse
result = urlparse(http://www.baidu.com/index.html;user?id=5#comment, scheme=https) # 指定协议类型
print(result)

##########################
# allow_fragments=False 一般不会用,把锚链接部分移动到参数(没有参数在往前移动#XXXX)
from urllib.parse import urlparse
result = urlparse(http://www.baidu.com/index.html#comment, allow_fragments=False)
print(result)

urlunparse

from urllib.parse import urlunparse
# 拼接网站
data = [http, www.baidu.com, index.html, user, a=6, comment]
print(urlunparse(data)) #http://www.baidu.com/index.html;user?a=6#comment

urljoin

from urllib.parse import urljoin
# 拼接
print(urljoin(http://www.baidu.com, Faq.html))
# 以第二个位基准
print(urljoin(http://www.baidu.com, https://www.baidu.com/aaa))
# 拼接
print(urljoin(http://www.baidu.com, ?a=1))

urlencode

# 参数化get参数
from urllib.parse import urlencode

params = {
    name: germey,
    age: 22
}
base_url = http://www.baidu.com?
url = base_url + urlencode(params)
print(url)    # http://www.baidu.com?name=germey&age=22

 

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