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  • 常见的爬虫分析库（1）-Python3中Urllib库基本使用

    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

    相比Python的变化

    Python2中的urllib2在Python3中被统一移动到了urllib.request中

    python2

    import urllib2

    response = urllib2.urlopen('http://www.cnblogs.com/0bug')

    Python3

    import urllib.request

    response = urllib.request.urlopen('http://www.cnblogs.com/0bug/')

    urlopen()

    不加data是以GET方式发送，加data是以POST发送

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    import urllib.request
     
    response = urllib.request.urlopen('http://www.cnblogs.com/0bug')
    html = response.read().decode('utf-8')
    print(html)
     结果

    加data发送POST请求

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    import urllib.parse
    import urllib.request
     
    data = bytes(urllib.parse.urlencode({'hello': '0bug'}), encoding='utf-8')
    response = urllib.request.urlopen('http://httpbin.org/post', data=data)
    print(response.read())
     结果

    timeout超时间

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    import urllib.request
     
    response = urllib.request.urlopen('http://www.cnblogs.com/0bug', timeout=0.01)
    print(response.read())
     结果
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    import urllib.request
    import socket
    import urllib.error
    try:
        response = urllib.request.urlopen('http://www.cnblogs.com/0bug', timeout=0.01)
    except urllib.error.URLError as  e:
        if isinstance(e.reason,socket.timeout):
            print('请求超时')
     结果

    响应

    1.响应类型

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    import urllib.request
     
    response = urllib.request.urlopen('http://www.cnblogs.com/0bug')
    print(type(response))
     结果

    2.状态码、响应头

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    import urllib.request
     
    response = urllib.request.urlopen('http://www.cnblogs.com/0bug')
    print(response.status)
    print(response.getheaders())
    print(response.getheader('Content-Type'))
     结果

    3.响应体

    响应体是字节流，需要decode('utf-8')

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    import urllib.request
     
    response = urllib.request.urlopen('http://www.cnblogs.com/0bug')
    html = response.read().decode('utf-8')
    print(html)

    Request

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    import urllib.request
     
    request = urllib.request.Request('http://www.cnblogs.com/0bug')
    response = urllib.request.urlopen(request)
    print(response.read().decode('utf-8'))
     结果

    添加请求头信息

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    from urllib import request, parse
     
    url = 'http://httpbin.org/post'
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36',
        'Host': 'httpbin.org'
    }
    dic = {'name': '0bug'}
    data = bytes(parse.urlencode(dic), encoding='utf-8')
    req = request.Request(url=url, data=data, headers=headers, method='POST')
    response = request.urlopen(req)
    print(response.read().decode('utf-8'))
     结果

    add_header

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    from urllib import request, parse
     
    url = 'http://httpbin.org/post'
    dic = {'name': '0bug'}
    data = bytes(parse.urlencode(dic), encoding='utf-8')
    req = request.Request(url=url, data=data, method='POST')
    req.add_header('User-Agent',
                   'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36')
    response = request.urlopen(req)
    print(response.read().decode('utf-8'))

    Handler

    代理：

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    import urllib.request
     
    proxy_handler = urllib.request.ProxyHandler({
        'http': 'http代理',
        'https': 'https代理'
    })
    opener = urllib.request.build_opener(proxy_handler)
    response = opener.open('http://www.cnblogs.com/0bug')
    print(response.read())

    Cookie

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    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)
     结果

    Cookie保存为文件

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    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)
     cookie.txt

    另一种方式存

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    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)
     cookie.txt

    用什么格式的存就应该用什么格式的读

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    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'))

    异常处理

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    from urllib import request, error
     
    try:
        response = request.urlopen('http://www.cnblogs.com/0bug/xxxx')
    except error.URLError as e:
        print(e.reason)
     结果
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    from urllib import request, error
     
    try:
        response = request.urlopen('http://www.cnblogs.com/0bug/xxxx')
    except error.HTTPError as e:
        print(e.reason, e.code, e.headers, sep=' ')
    except error.URLError as e:
        print(e.reason)
    else:
        print('Request Successfully')
     结果
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    import socket
    import urllib.request
    import urllib.error
     
    try:
        response = urllib.request.urlopen('http://www.cnblogs.com/0bug/xxxx', timeout=0.001)
    except urllib.error.URLError as e:
        print(type(e.reason))
        if isinstance(e.reason, socket.timeout):
            print('请求超时')
     结果

    URL解析

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    from urllib.parse import urlparse
     
    result = urlparse('www.baidu.com/index.html;user?id=5#comment')
    print(type(result))
    print(result)
     结果
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    from urllib.parse import urlparse
     
    result = urlparse('www.baidu.com/index.html;user?id=5#comment', scheme='https')
    print(result)
     结果
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    from urllib.parse import urlparse
     
    result = urlparse('http://www.baidu.com/index.html;user?id=5#comment', scheme='https')
    print(result)
     结果
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    from urllib.parse import urlparse
     
    result = urlparse('http://www.badiu.com/index.html;user?id=5#comment', allow_fragments=False)
    print(result)
     结果
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    from urllib.parse import urlparse
     
    result = urlparse('http://www.badiu.com/index.html#comment', allow_fragments=False)
    print(result)
     结果

    urlunparse

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    from urllib.parse import urlunparse
     
    data = ['http', 'www.baidu.com', 'index.html', 'user', 'id=6', 'comment']
    print(urlunparse(data))
     结果

    urljoin

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    from urllib.parse import urljoin
     
    print(urljoin('http://www.baidu.com', 'ABC.html'))
    print(urljoin('http://www.baidu.com', 'https://www.cnblogs.com/0bug'))
    print(urljoin('http://www.baidu.com/0bug', 'https://www.cnblogs.com/0bug'))
    print(urljoin('http://www.baidu.com/0bug', 'https://www.cnblogs.com/0bug?q=2'))
    print(urljoin('http://www.baidu.com/0bug?q=2', 'https://www.cnblogs.com/0bug'))
    print(urljoin('http://www.baidu.com', '?q=2#comment'))
    print(urljoin('www.baidu.com', '?q=2#comment'))
    print(urljoin('www.baidu.com#comment', '?q=2'))
     结果

    urlencode

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    from urllib.parse import urlencode
     
    params = {
        'name': '0bug',
        'age': 25
    }
    base_url = 'http://www.badiu.com?'
    url = base_url + urlencode(params)
    print(url)
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  • 原文地址：https://www.cnblogs.com/yunlongaimeng/p/9802052.html
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