python爬虫系列(2.1-requests库的基本的使用)

一、基本认识

• 1、发送一个get请求

    import requests

    if __name__ == "__main__":
        # 获取一个get请求
        response = requests.get('http://httpbin.org/get')

• 2、关于获取请求到数据常见的返回值

    import requests

    if __name__ == "__main__":
        # 获取一个get请求
        response = requests.get('http://httpbin.org/get')
        # 对抓取的网站设置编码
        response.encoding = 'utf-8'
        # 打印返回的数据
        print(response.text)
        print(response.json())
        print(response.headers)
        print(response.status_code)
        print(response.url)
        print(response.cookies)
        print(response.json())
        # 获取最原始的字符串,没有编码的(用户response.text出现乱码的时候,及下载二进制文件的时候)
        print(response.content)

• 3、关于其他的请求方式

    response = requests.post('http://httpbin.org/post')
    response = requests.put('http://httpbin.org/put')
    response = requests.delete('http://httpbin.org/delete')
    response = requests.head('http://httpbin.org/get')
    response = requests.options('http://httpbin.org/get')

二、关于get请求传递参数的

• 1、直接在url地址后面拼接参数

    import requests

    if __name__ == "__main__":
        # 定义一个请求头(模拟浏览器)
        headers = {'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36'}
        # 设置参数
        data = {'name': 'june', 'password': 123456}
        # 获取一个get请求
        response = requests.get('http://httpbin.org/get?name=june&password=123456', headers=headers)
        # 对抓取的网站设置编码
        response.encoding = 'utf-8'
        print(response.text)

• 2、使用params传递参数

    import requests

    if __name__ == "__main__":
        # 定义一个请求头(模拟浏览器)
        headers = {'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36'}
        # 设置参数
        data = {'name': 'june', 'password': 123456}
        # 获取一个get请求
        response = requests.get('http://httpbin.org/get', headers=headers, params=data)
        # 对抓取的网站设置编码
        response.encoding = 'utf-8'
        print(response.text)

三、使用requests库和正则表达式下载文章内容

• 1、需要下载的伯乐在线的文章标题
• 2、书写逻辑代码

    import re
    import requests

    if __name__ == "__main__":
        headers = {
            'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36',
        }
        url = 'http://python.jobbole.com/category/guide/'

        response = requests.get(url=url, headers=headers)
        pattern = re.compile(
            '<div.*?post-thumb.*?title="(.*?)".*?</a>', re.S
        )
        print(response.status_code)
        result_list = re.findall(pattern, response.text)

        f = open('jobbole1.txt', 'a+', encoding='utf8')
        for item in result_list:
            f.write(item.strip() + '\n')
        f.close()

• 3、解说正则表达式
  • .*?表示非贪婪的匹配任何字符
  • re.S 使.匹配包括换行在内的全部字符

四、使用requests库和正则表达式下载图片

• 1、导包

    import re
    import os
    import shutil
    import requests

• 2、定义一个下载图片的类

    class DownPic(object):
            def __init__(self):
                    self.url = 'http://python.jobbole.com/category/guide/'
                    self.headers = {
                            'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36',
                    }
                    self.create_dir()

            def create_dir(cls):
                    # 如果文件夹存在就删除
                    if os.path.exists('demo'):
                            shutil.rmtree('demo')
                    os.makedirs('demo')

            def get_html(self):
                    response = requests.get(url=self.url, headers=self.headers)
                    return response.text

            def pattern(self):
                    pattern = re.compile(
                            '<div.*?post-thumb.*?src="(.*?)".*?</a>', re.S
                    )
                    result_list = re.findall(pattern, self.get_html())
                    return result_list

            def download(self):
                    for item in self.pattern():
                            # 获取到的图片地址再次请求
                            if item.rsplit('.')[-1] in ['png', 'jpg']:
                                    resp = requests.get(item.strip())
                                    try:
                                            with open(os.path.join('demo', item.strip().rsplit("/")[-1]), 'wb') as f:
                                                    f.write(resp.content)
                                    except Exception as e:
                                            print(e)
                            else:
                                    continue

• 3、调用

    if __name__ == "__main__":
            p = DownPic()
            p.download()

五、关于requests库的post请求

• 1、格式

    response = requests.post('http://httpbin.org/post', headers=headers, data=data)

• 2、发送数据到服务器端

    import requests

    if __name__ == "__main__":
            # 定义一个请求头(模拟浏览器)
            headers = {
                    'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36'}
            # 设置参数
            data = {'email': '22@qq.com', 'password': 123456}
            # 获取一个get请求
            response = requests.post('https://httpbin.org/post', headers=headers, data=data)
            # 对抓取的网站设置编码
            response.encoding = 'utf-8'
            print(response.text)

六、使用post请求获取拉勾网职业信息

import requests

if __name__ == "__main__":
        url = 'https://www.lagou.com/jobs/positionAjax.json?needAddtionalResult=false'
        headers = {
                'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.162 Safari/537.36',
                'Referer': 'https://www.lagou.com/jobs/list_python?labelWords=&fromSearch=true&suginput='
        }
        data = {
                'first': 'true',
                'pn': '1',
                'kd': 'python',
        }

        response = requests.post(url=url, headers=headers, data=data)
        print(response.json())

七、更多关于python爬虫文章可以访问