python requests简介

　　更为强大的库requests是为了更加方便地实现爬虫操作,有了它 ， Cookies 、登录验证、代理设置等操作都不是 .

　　

一、安装requests模块(cmd窗口执行)

pip3 install requests

二、requests的基本方法

import requests
response=requests.get("https://www.baidu.com/")
print(type(response)) #<class 'requests.models.Response'> response类型
print(response.status_code) #200 获取状态码
print(response.text) #获取网页源码
print(response.content) #获取网页源码
print(response.cookies) #获取网页cookies ，Req u estsCookieJar
print(response.headers) #获取请求头 

三、推荐一个测试网址：http://httpbin.org测试请求网站，可以随便捣鼓（其他请求方式）

import requests
r=requests.post("http://httpbin.org/post")
print(r.text) #打印post请求的头部信息
r=requests.put("http://httpbin.org/post")
r=requests.delete("http://httpbin.org/post")
r=requests.options("http://httpbin.org/post")

　　这里分别用 post （）、 put （）、 delete （）等方法实现了 POST 、 PUT 、 DELETE 等请求 。

四、get 请求

　　查看get请求包含的请求信息

import requests
r=requests.get("http://httpbin.org/get")
print(r.text) #打印get请求信息

结果显示：
{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "origin": "119.123.196.143",
  "url": "http://httpbin.org/get"
}

　　结果显示说明：一个请求信息应该包含了请求头、ip地址、URL等信息。

　　（1）请求添加额外信息

　　　　方法一：？key=value&key2=value2... (?：表示起始，&：表示和)

r= requests.get("http://httpbin.org/get?name=germey&age=22")

import requests
r= requests.get("http://httpbin.org/get?name=germey&age=22")
print(r.text)

方法一示例

{
  "args": {
    "age": "",
    "name": "germey"
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "origin": "119.123.196.143",
  "url": "http://httpbin.org/get?name=germey&age=22"
}

方法一结果

　　通过运行结果可以判断，请求的链接自动被构造成了：http://httpbin.org/get?name=germey&age=22
　　　　

　　方法二：利用get 里面参数params，可以将请求信息编译加载到url中（推荐使用）

import requests

data={
    "name":"germey",
    "age":22
}
r=requests.get("http://httpbin.org/get",params=data)
print(r.text)

结果显示：
{
  "args": {
    "age": "",
    "name": "germey"
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "origin": "119.123.196.143",
  "url": "http://httpbin.org/get?name=germey&age=22"
}

方法二结果

　　结果都构造了：http://httpbin.org/get?name=germey&age=22，方法二比较实用

　　（2）从网页请求到的请求信息都是json格式字符串，转换成字典dict,使用 .json()；

　　　　如果不是Json格式，则报错：JSON。decodeJSONDecodeError异常

import requests
r=requests.get("http://httpbin.org/get")
print(type(r.text)) #查看请求头数据类型
print(r.text) #打印请求信息
#r.json() 将json字符串转换为字典
print(type(r.json()))#转换为dict，打印数据类型

<class 'str'>
{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "origin": "119.123.196.143",
  "url": "http://httpbin.org/get"
}

<class 'dict'>

结果

　　结果显示：请求信息是<str>；r.json（）后的数据是<dict>

五、get方法请求抓取网页实例

　　(1)成功获取知乎的网页信息

# 请求知乎
import requests
#构建请求要求信息
data={
    "type":"content",
    "q":"赵丽颖"
      }
url="https://www.zhihu.com/search"
#构建请求的ip和服务器信息
headers={
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36"  ,
    "origin": "119.123.196.143",
}
response=requests.get(url,params=data,headers=headers)
print(response.text)

添加搜索信息和headrs信息

　　这里我们加入了 headers 信息，其中包含了 User- Agent 字段信息， 也就是浏览器标识信息 。 如果
不加这个 ，知乎会禁止抓取,data构造了一个请求搜索信息.
　　(2)github站点图标下载

import requests
r=requests.get(" https://github.com/favicon.ico")
print(r.text)
print(r.content)
with open("github.ico","wb") as f:
    f.write(r.content)

打印图标示例

　　(3)请求头信息headers

{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "origin": "119.123.196.143",
  "url": "https://httpbin.org/get"
}

　　(4)抓取github图标

　　　　r.text  得到的数据是字符串类型

　　　　r.content 得到的数据是bytes类型数据

import requests
r = requests.get("https://github.com/favicon.ico")
print('text',r.text)#获取到字符串
print('content',r.content) #获取的是二进制

import requests
r=requests.get(" https://github.com/favicon.ico")
print(r.text)
print(r.content)
with open("gg.ico","wb") as f:
    f.write(r.content)

github图片写入

六、post请求

　　带data信息请求

import requests
data ={
    'name' :'pig',
    'age':18
}
r = requests.post('http://httpbin.org/post', data=data)
print(r.text)

{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "age": "",
    "name": "pig"
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Content-Length": "",
    "Content-Type": "application/x-www-form-urlencoded",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.20.1"
  },
  "json": null,
  "origin": "119.123.198.80",
  "url": "http://httpbin.org/post"
}

post请求信息

七、请求状态码

　　1、100状态码：信息状态码

　　2、200状态码：成功状态码

　　3、300状态吗：重定向状态码

　　4、400状态码：客户端错误状态码

　　5、500状态码：服务器错误状态码

import requests
import re

def get(url,session):
    headers={
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.100 Safari/537.36",
    "Host": "book.douban.com"
    }
    response=session.get(url,headers=headers)
    return response.content.decode("utf-8")

def parse(path,data,session):
    res=session.get(data,timeout=2)
    with open(path,"wb") as f:
        f.write(res.content)

if __name__ == '__main__':
    obj=re.compile('<img src="(?P<picture>.*?)"')
    session = requests.session()
    html=get("https://book.douban.com/",session)
    pic_url_list=obj.findall(html,re.S)
    n=1

    for pic_url in pic_url_list:
        print(pic_url)
        try:
            path=r"book_picture/"+f"{n}"+".jpg"
            parse(path,pic_url,session)
            n+=1

        except Exception as e:
            print(e)

豆瓣图片爬取实例

#coding=utf-8
import  requests
import os
import re

def getHtml(url):
    headers={
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
        "Cookie": "BDqhfp=%E5%90%8D%E8%83%9C%E5%8F%A4%E8%BF%B9%26%26-10-1undefined%26%260%26%261; BAIDUID=3E9EFDBD86FBFCF2DA4C32A06482351C:FG=1; BIDUPSID=E013F7397D0EF0F46FFAF97FC8A7F349; PSTM=1543903169; pgv_pvi=2584268800; delPer=0; PSINO=7; BDRCVFR[5VG_cZ6c41T]=9xWipS8B-FspA7EnHc1QhPEUf; ZD_ENTRY=baidu; BDRCVFR[dG2JNJb_ajR]=mk3SLVN4HKm; indexPageSugList=%5B%22%E5%90%8D%E8%83%9C%E5%8F%A4%E8%BF%B9%22%5D; cleanHistoryStatus=0; BDRCVFR[-pGxjrCMryR]=mk3SLVN4HKm; BCLID=7951205421696906576; BDSFRCVID=_rLOJeC629zHWkc9ByJPtBGK9T-me2jTH6bH27NMSSL8H8ptFoAvEG0PjM8g0KubkDpOogKK3gOTH4PF_2uxOjjg8UtVJeC6EG0P3J; H_BDCLCKID_SF=tJI8_DLytD_3JRcFDDTb-tCqMfTM2n58a5IX3buQX-od8pcNLTDKeJIn3UR2qxj8WHRJ5q3cfx-VDJK4MlO1j4DnDGJwWlJgBnb7VPJ23J7Nfl5jDh38XjksD-Rt5tnR-gOy0hvctb3cShPm0MjrDRLbXU6BK5vPbNcZ0l8K3l02VKO_e4bK-Tr3jaDetU5; H_PS_PSSID=; BDORZ=FFFB88E999055A3F8A630C64834BD6D0; userFrom=blog.csdn.net",
        "Host": "image.baidu.com",
        "Upgrade-Insecure-Requests":"",
         "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36"
    }
    page = requests.get(url,headers=headers)
    html = page.content.decode()
    return html

if __name__ == '__main__':

    msg=input("请输入搜索内容<如苍老师>:")
    os.mkdir(msg)
    html = getHtml(f"https://image.baidu.com/search/index?ct=201326592&cl=2&st=-1&lm=-1&nc=1&ie=utf-8&tn=baiduimage&ipn=r&rps=1&pv=&word={msg}&hs=0&oriquery=%E5%90%8D%E8%83%9C%E5%8F%A4%E8%BF%B9&ofr=%E5%90%8D%E8%83%9C%E5%8F%A4%E8%BF%B9&z=0&ic=0&face=0&width=0&height=0&latest=0&s=0&hd=0&copyright=0&selected_tags=%E7%AE%80%E7%AC%94%E7%94%BB")

    obj=re.compile('"thumbURL":"(?P<pic>.*?)"',re.S)
    pic_list=obj.findall(html)
    n=1
    for pic_url in pic_list:
        print(pic_url)
        try:
            data=requests.get(pic_url,timeout=2)
            path=f"{msg}/"+f"{n}"+".jpg"
            with open(path,"wb") as f:
                print("-----------正在下载图片----------")
                f.write(data.content)
                n+=1
                print("----------下载完成----------")
        except Exception as e:
            print(e)

百度图片静态爬取（待优化）