Python利用Requests库写爬虫（一）

• 基本Get请求：

#-*- coding:utf-8 -*-
import requests
url = 'http://www.baidu.com'
r = requests.get(url)
print r.text

• 带参数Get请求：

#-*- coding:utf-8 -*-
import requests
url = 'http://www.baidu.com'
payload = {'key1': 'value1', 'key2': 'value2'}
r = requests.get(url, params=payload)
print r.text

• POST请求模拟登陆及一些返回对象的方法：

#-*- coding:utf-8 -*-
import requests
url1 = 'http://www.exanple.com/login'#登陆地址
url2 = "http://www.example.com/main"#需要登陆才能访问的地址
data={"user":"user","password":"pass"}
headers = { "Accept":"text/html,application/xhtml+xml,application/xml;",
            "Accept-Encoding":"gzip",
            "Accept-Language":"zh-CN,zh;q=0.8",
            "Referer":"http://www.example.com/",
            "User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36"
            }
res1 = requests.post(url1, data=data, headers=headers)
res2 = requests.get(url2, cookies=res1.cookies, headers=headers)

print res2.content#获得二进制响应内容
print res2.raw#获得原始响应内容,需要stream=True
print res2.raw.read(50)
print type(res2.text)#返回解码成unicode的内容
print res2.url
print res2.history#追踪重定向
print res2.cookies
print res2.cookies['example_cookie_name']
print res2.headers
print res2.headers['Content-Type']
print res2.headers.get('content-type')
print res2.json#讲返回内容编码为json
print res2.encoding#返回内容编码
print res2.status_code#返回http状态码
print res2.raise_for_status()#返回错误状态码

• 使用Session()对象的写法（Prepared Requests）:

#-*- coding:utf-8 -*-
import requests
s = requests.Session()
url1 = 'http://www.exanple.com/login'#登陆地址
url2 = "http://www.example.com/main"#需要登陆才能访问的地址
data={"user":"user","password":"pass"}
headers = { "Accept":"text/html,application/xhtml+xml,application/xml;",
            "Accept-Encoding":"gzip",
            "Accept-Language":"zh-CN,zh;q=0.8",
            "Referer":"http://www.example.com/",
            "User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36"
            }

prepped1 = requests.Request('POST', url1,
    data=data,
    headers=headers
).prepare()
s.send(prepped1)


'''
也可以这样写
res = requests.Request('POST', url1,
data=data,
headers=headers
)
prepared = s.prepare_request(res)
# do something with prepped.body
# do something with prepped.headers
s.send(prepared)
'''

prepare2 = requests.Request('POST', url2,
    headers=headers
).prepare()
res2 = s.send(prepare2)

print res2.content

• 另一种写法 :

#-*- coding:utf-8 -*-
import requests
s = requests.Session()
url1 = 'http://www.exanple.com/login'#登陆地址
url2 = "http://www.example.com/main"#需要登陆才能访问的页面地址
data={"user":"user","password":"pass"}
headers = { "Accept":"text/html,application/xhtml+xml,application/xml;",
            "Accept-Encoding":"gzip",
            "Accept-Language":"zh-CN,zh;q=0.8",
            "Referer":"http://www.example.com/",
            "User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36"
            }
res1 = s.post(url1, data=data)
res2 = s.post(url2)
print(resp2.content)

SessionApi

• 其他的一些请求方式

>>> r = requests.put("http://httpbin.org/put")
>>> r = requests.delete("http://httpbin.org/delete")
>>> r = requests.head("http://httpbin.org/get")
>>> r = requests.options("http://httpbin.org/get")

遇到的问题:

在cmd下执行，遇到个小错误:

UnicodeEncodeError:'gbk' codec can't encode character u'\xbb' in   
position 23460: illegal multibyte sequence

分析:
1、Unicode是编码还是解码

UnicodeEncodeError

很明显是在编码的时候出现了错误

2、用了什么编码

'gbk' codec can't encode character

使用GBK编码出错

解决办法：

确定当前字符串，比如

#-*- coding:utf-8 -*-
import requests
url = 'http://www.baidu.com'
r = requests.get(url)
print r.encoding
>utf-8

已经确定html的字符串是utf-8的，则可以直接去通过utf-8去编码。

print r.text.encode('utf-8')

参考链接：官方文档