概述
什么是Requests
Requests是用python语言基于urllib编写的,采用的是Apache2 Licensed开源协议的HTTP库如果你看过上篇文章关于urllib库的使用,你会发现,其实urllib还是非常不方便的,而Requests它会比urllib更加方便,可以节约我们大量的工作。(用了requests之后,你基本都不愿意用urllib了)一句话,requests是python实现的最简单易用的HTTP库,建议爬虫使用requests库。
默认安装好python之后,是没有安装requests模块的,需要单独通过pip安装
功能详解
response = requests.get("https://www.baidu.com")
print(type(response))
print(response.status_code)
print(type(response.text))
print(response.text)
print(response.cookies)
print(response.content)
print(response.content.decode("utf-8"))
我们可以看出response使用起来确实非常方便,这里有个问题需要注意一下:很多情况下的网站如果直接response.text会出现乱码的问题,所以这个使用response.content这样返回的数据格式其实是二进制格式,然后通过decode()转换为utf-8,这样就解决了通过response.text直接返回显示乱码的问题.
请求发出后,Requests 会基于 HTTP 头部对响应的编码作出有根据的推测。当你访问 response.text 之时,Requests 会使用其推测的文本编码。你可以找出 Requests 使用了什么编码,并且能够使用 response.encoding 属性来改变它.如:
不管是通过response.content.decode("utf-8)的方式还是通过response.encoding="utf-8"的方式都可以避免乱码的问题发生
requests里提供个各种请求方式
请求
基本GET请求
response = requests.get('http://httpbin.org/get')
print(response.text)
带参数的GET请求,例子1
response = requests.get("http://httpbin.org/get?name=zhaofan&age=23")
print(response.text)
如果我们想要在URL查询字符串传递数据,通常我们会通过httpbin.org/get?key=val方式传递。Requests模块允许使用params关键字传递参数,以一个字典来传递这些参数,例子如下:
上述两种的结果是相同的,通过params参数传递一个字典内容,从而直接构造url注意:第二种方式通过字典的方式的时候,如果字典中的参数为None则不会添加到url上
解析json
response = requests.get("http://httpbin.org/get")
print(type(response.text))
print(response.json())
print(json.loads(response.text))
print(type(response.json()))
从结果可以看出requests里面集成的json其实就是执行了json.loads()方法,两者的结果是一样的
获取二进制数据
在上面提到了response.content,这样获取的数据是二进制数据,同样的这个方法也可以用于下载图片以及视频资源
添加headers和前面我们将urllib模块的时候一样,我们同样可以定制headers的信息,如当我们直接通过requests请求知乎网站的时候,默认是无法访问的
这样会得到如下的错误
因为访问知乎需要头部信息,这个时候我们在谷歌浏览器里输入chrome://version,就可以看到用户代理,将用户代理添加到头部信息
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<div class="cnblogs_code">
import requests
headers = {
"User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/58.0.3029.110 Safari/537.36"<span>
}
response =requests.get("https://www.zhihu.com",headers=headers)
print(response.text)
"User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/58.0.3029.110 Safari/537.36"<span>
}
response =requests.get("https://www.zhihu.com",headers=headers)
print(response.text)
"User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/58.0.3029.110 Safari/537.36"<span>
}
response =requests.get("https://www.zhihu.com",headers=headers)
print(response.text)
这样就可以正常的访问知乎了
基本POST请求
通过在发送post请求时添加一个data参数,这个data参数可以通过字典构造成,这样对于发送post请求就非常方便
data = {
"name":"zhaofan","age":23
}
response = requests.post("http://httpbin.org/post",data=data)
print(response.text)
同样的在发送post请求的时候也可以和发送get请求一样通过headers参数传递一个字典类型的数据
响应
我们可以通过response获得很多属性,例子如下
response = requests.get("http://www.baidu.com")
print(type(response.status_code),response.status_code)
print(type(response.headers),response.headers)
print(type(response.cookies),response.cookies)
print(type(response.url),response.url)
print(type(response.history),response.history)
结果如下:
状态码判断Requests还附带了一个内置的状态码查询对象主要有如下内容:
100: ('continue',),101: ('switching_protocols',102: ('processing',103: ('checkpoint',122: ('uri_too_long','request_uri_too_long'),200: ('ok','okay','all_ok','all_okay','all_good','\o/','?'),201: ('created',202: ('accepted',203: ('non_authoritative_info','non_authoritative_information'),204: ('no_content',205: ('reset_content','reset'),206: ('partial_content','partial'),207: ('multi_status','multiple_status','multi_stati','multiple_stati'),208: ('already_reported',226: ('im_used',
Redirection.300: ('multiple_choices',301: ('moved_permanently','moved','\o-'),302: ('found',303: ('see_other','other'),304: ('not_modified',305: ('use_proxy',306: ('switch_proxy',307: ('temporary_redirect','temporary_moved','temporary'),308: ('permanent_redirect','resume_incomplete','resume',# These 2 to be removed in 3.0
Client Error.400: ('bad_request','bad'),401: ('unauthorized',402: ('payment_required','payment'),403: ('forbidden',404: ('not_found','-o-'),405: ('method_not_allowed','not_allowed'),406: ('not_acceptable',407: ('proxy_authentication_required','proxy_auth','proxy_authentication'),408: ('request_timeout','timeout'),409: ('conflict',410: ('gone',411: ('length_required',412: ('precondition_Failed','precondition'),413: ('request_entity_too_large',414: ('request_uri_too_large',415: ('unsupported_media_type','unsupported_media','media_type'),416: ('requested_range_not_satisfiable','requested_range','range_not_satisfiable'),417: ('expectation_Failed',418: ('im_a_teapot','teapot','i_am_a_teapot'),421: ('misdirected_request',422: ('unprocessable_entity','unprocessable'),423: ('locked',424: ('Failed_dependency','dependency'),425: ('unordered_collection','unordered'),426: ('upgrade_required','upgrade'),428: ('precondition_required',429: ('too_many_requests','too_many'),431: ('header_fields_too_large','fields_too_large'),444: ('no_response','none'),449: ('retry_with','retry'),450: ('blocked_by_windows_parental_controls','parental_controls'),451: ('unavailable_for_legal_reasons','legal_reasons'),499: ('client_closed_request',
Server Error.500: ('internal_server_error','server_error','/o\','?'),501: ('not_implemented',502: ('bad_gateway',503: ('service_unavailable','unavailable'),504: ('gateway_timeout',505: ('http_version_not_supported','http_version'),506: ('variant_also_negotiates',507: ('insufficient_storage',509: ('bandwidth_limit_exceeded','bandwidth'),510: ('not_extended',511: ('network_authentication_required','network_auth','network_authentication'),
通过下面例子测试:(不过通常还是通过状态码判断更方便)
<div class="cnblogs_code">
import requests
response= requests.get("http://www.baidu.com")
if response.status_code == requests.codes.ok:
print("访问成功")
response= requests.get("http://www.baidu.com")
if response.status_code == requests.codes.ok:
print("访问成功")
response= requests.get("http://www.baidu.com")
if response.status_code == requests.codes.ok:
print("访问成功")
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