从0开始学爬虫2之json的介绍和使用

从0开始学爬虫2之json的介绍和使用

Json

• 一种轻量级的数据交换格式，通用，跨平台
• 键值对的集合，值的有序列表
• 类似于python中的dict

Json中的键值如果是字符串一定要用双引号

json文件static/book.json

{
  "name": "Python书籍",
  "origin_price": ,
  "pub_date": "2018-4-14 17:00:00",
  "store": ["京东","淘宝"],
  "author": ["张三","李四","Jhone"],
  "is_valid":true,
  "is_sale": false,
  "meta":{
      "isbn":"abc-123",
      "pages":
  },
  "desc":null
}

Json的常用方法练习use_json.py

#coding=utf-8

import json

def python_to_json():
    """将python对象转换成json"""
    d = {
        'name': 'python书籍',
        'price':62.3,
        'is_valid': True
    }
    # intend是加入缩进效果
    rest = json.dumps(d, indent=4)
    print(rest)

def json_to_python():
    """  将json转换成python """
    data = '''
        {
          "name": "Python书籍",
          "origin_price": 66,
          "pub_date": "2018-4-14 17:00:00",
          "store": ["京东","淘宝"],
          "author": ["张三","李四","Jhone"],
          "is_valid":true,
          "is_sale": false,
          "meta":{
              "isbn":"abc-123",
              "pages":300
          },
          "desc":null
        }
    '''
    rest = json.loads(data)
    print(rest)

def json_to_python_from_file():
    """从文件读取内容并转换为python对象"""
    f = open('./static/book.json', 'r', encoding='utf-8')

    s = f.read()
    print(s)
    rest = json.loads(s)
    print(rest["name"])

    f.close()

if __name__ == '__main__':
    python_to_json()
    # json_to_python()
    # json_to_python_from_file()