Python爬虫(1) 开篇
urllib操作URL的模块
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例：from urllib import request
request.urlopen() 抓取网页函数
例：r = request.urlopen('http://www.baidu.com')
r.read() 返回页面的HTML全部代码
r.readline() 返回页面HTML一样代码
r.readlines() 返回列表形式的HTML全部代码
r.info() 返回当前环境信息
例：Bdpagetype: 1
Bdqid: 0xdefca0ed00016e4e
Cache-Control: private
Content-Type: text/html
Cxy_all: baidu+430f78810ad19b54eeba51879195387f
Date: Thu, 22 Nov 2018 03:35:22 GMT
Expires: Thu, 22 Nov 2018 03:34:29 GMT
P3p: CP=" OTI DSP COR IVA OUR IND COM "
Server: BWS/1.1
Set-Cookie: BAIDUID=22A080159BC1AB4FE37099B28FE016B6:FG=1; expires=Thu, 31-Dec-37 23:5
5:55 GMT; max-age=2147483647; path=/; domain=.baidu.com
Set-Cookie: BIDUPSID=22A080159BC1AB4FE37099B28FE016B6; expires=Thu, 31-Dec-37 23:55:55
GMT; max-age=2147483647; path=/; domain=.baidu.com
Set-Cookie: PSTM=1542857722; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647;
path=/; domain=.baidu.com
Set-Cookie: delPer=0; path=/; domain=.baidu.com
Set-Cookie: BDSVRTM=0; path=/
Set-Cookie: BD_HOME=0; path=/
Set-Cookie: H_PS_PSSID=1467_21100_18559; path=/; domain=.baidu.com
Vary: Accept-Encoding
X-Ua-Compatible: IE=Edge,chrome=1
Connection: close
Transfer-Encoding: chunked
r.getcode() 返回当前抓取页面的请求状态码
例：200
request.urlretrieve() 抓取页面并写入文件
例：r = request.urlretrieve('http://www.baidu.com',filename='./2.html')
urlretrieve() 会产生缓存文件，如果要清楚缓存使用urlcleanup()
例：r.urlcleanup()
quote() 字符串转换为ASCII编码
例：s = request.quote('http://www.baidu.com')
print(s)
http%3A//www.baidu.com
unquote() 反ASCII编码
build_opener().addheaders 属性修改header头
例：from urllib import request as sa
url = 'https://blog.csdn.net/dQCFKyQDXYm3F8rB0/article/details/84302896'
headers = ('User-Agent','Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.26 Safari/537.36 Core/1.63.6776.400 QQBrowser/10.3.2601.400')
dds = sa.build_opener()
dds.addheaders = [headers]
d = dds.open(url).read()
f = open('./1.html','wb')
f.write(d)
f.close()
