python3好用的requests库

requests是什么？

requests是基于urllib编写的http库，支持python3，比urllib更好用，更简单。之前使用python写一些http请求或者爬虫的脚本使用的是urllib来获取html，后来发现用requests方便很多。

安装方法

1、使用pip进行安装

pip install requests

2、下载代码安装
在github上（https://github.com/kennethreitz/requests）直接下载源代码（或者clone到本地，需要安装git），然后再目录下执行

python setup.py install

3、通过IDE工具去安装，许多IDE工具提供安装方法，例如pycharm之类的

使用方法

首先，查看一下帮助文件，里面有最基本的说明

import requests
help(requests)

帮助文档里给出了发送get和post请求的最简单实例：

 Requests is an HTTP library, written in Python, for human beings. Basic GET
    usage:
    
       >>> import requests
       >>> r = requests.get('https://www.python.org')
       >>> r.status_code
       200
       >>> 'Python is a programming language' in r.content
       True
    
    ... or POST:
    
       >>> payload = dict(key1='value1', key2='value2')
       >>> r = requests.post('http://httpbin.org/post', data=payload)
       >>> print(r.text)
       {
         ...
         "form": {
           "key2": "value2",
           "key1": "value1"
         },
         ...
       }

写一个简单请求的例子：

import requests

#post
url = 'xxx'
FromData = {key1:value,key2:value}
RequestHeaders = {"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
                  "Accept-Encoding":"utf-8",
                  "Accept-Language":"zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3",
                  "Connection":"keep-alive",
                  "Host":"xxx",
                  "User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0"}
test = requests.post(url , data = FromData , headers = RequestHeaders)

#get
url = 'xxx'
#FromData = {key1:value,key2:value}
RequestHeaders = {"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
                  "Accept-Encoding":"utf-8",
                  "Accept-Language":"zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3",
                  "Connection":"keep-alive",
                  "Host":"xxx",
                  "Referer":"xxx",
                  "User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0",
                  "cookie":"sid=xxx"}
test = requests.get(url , headers = RequestHeaders, params={xx})

发送请求后会返回一个requests的类

type(test)
>>><class 'requests.models.Response'>
dir(test)
>>>['__attrs__', '__bool__', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__nonzero__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_content', '_content_consumed', 'apparent_encoding', 'close', 'connection', 'content', 'cookies', 'elapsed', 'encoding', 'headers', 'history', 'is_permanent_redirect', 'is_redirect', 'iter_content', 'iter_lines', 'json', 'links', 'ok', 'raise_for_status', 'raw', 'reason', 'request', 'status_code', 'text', 'url']

可以选择相应的方法，对其进行处理
ps：配合beautifulsoup效果更佳

使用requests进行下载文件

a = requests.get(r'http://192.168.1.245:8080/static/stage/headImg/test.jpg',stream=True)    #stream = True,进行请求后不回立即下载文件，这样避免文件过大，内存不足，后面设置chunk_size来将文件分块下载
with open('C:\test.jpg','wb')as f:
    for i in a.iter_content(chunk_size=512):      #iter_content：一块一块的遍历要下载的内容；iter_lines：一行一行的遍历要下载的内容
        if i:
            f.write(i)