python的json模块的dumps，loads，dump，load方法介绍

dumps和loads方法都在内存中转换，
dump和load的方法会多一个步骤，dump是把序列化后的字符串写到一个文件中，而load是从一个文件中读取字符串

>>> a=[1,2,3,4,5]
>>> import json
>>> json.dumps(a)
‘[1, 2, 3, 4, 5]‘
>>> type(json.dumps(a))
<class ‘str‘>
>>> 

>>> b={"cc":12,"vv":33}
>>> json.dumps(b)
‘{"cc": 12, "vv": 33}‘
>>> type(json.dumps(b))
<class ‘str‘>

>>> f=json.dumps(a)
>>> f
‘[1, 2, 3, 4, 5]‘
>>> json.loads(f)
[1, 2, 3, 4, 5]

>>> k=json.dumps(b)
>>> k
‘{"cc": 12, "vv": 33}‘
>>> json.loads(k)
{‘cc‘: 12, ‘vv‘: 33}
>>> 

#coding=utf-8
import requests
import json
#
ret = requests.get(‘http://wthrcdn.etouch.cn/weather_mini?city=北京‘)
ret.encoding = ‘utf-8‘
s1 = ret.text
print(s1,type(s1))

d1 = json.loads(s1)
print(d1,type(d1))

{
    "data": {
        "yesterday": {
            "date": "16日星期六",
            "high": "高温 3℃",
            "fx": "北风",
            "low": "低温 -6℃",
            "fl": "<![CDATA[3-4级]]>",
            "type": "晴"
        },
        "city": "北京",
        "forecast": [{
            "date": "17日星期天",
            "high": "高温 6℃",
            "fengli": "<![CDATA[<3级]]>",
            "low": "低温 -4℃",
            "fengxiang": "北风",
            "type": "晴"
        }, {
            "date": "18日星期一",
            "high": "高温 4℃",
            "fengli": "<![CDATA[<3级]]>",
            "low": "低温 -3℃",
            "fengxiang": "南风",
            "type": "阴"
        }, {
            "date": "19日星期二",
            "high": "高温 7℃",
            "fengli": "<![CDATA[<3级]]>",
            "low": "低温 -4℃",
            "fengxiang": "西南风",
            "type": "多云"
        }, {
            "date": "20日星期三",
            "high": "高温 9℃",
            "fengli": "<![CDATA[<3级]]>",
            "low": "低温 -4℃",
            "fengxiang": "北风",
            "type": "晴"
        }, {
            "date": "21日星期四",
            "high": "高温 11℃",
            "fengli": "<![CDATA[<3级]]>",
            "low": "低温 -3℃",
            "fengxiang": "西南风",
            "type": "晴"
        }],
        "ganmao": "各项气象条件适宜，无明显降温过程，发生感冒机率较低。",
        "wendu": "-2"
    },
    "status": 1000,
    "desc": "OK"
} < class ‘str‘ > 

{
    ‘data‘: {
        ‘yesterday‘: {
            ‘date‘: ‘16日星期六‘,
            ‘high‘: ‘高温 3℃‘,
            ‘fx‘: ‘北风‘,
            ‘low‘: ‘低温 -6℃‘,
            ‘fl‘: ‘<![CDATA[3-4级]]>‘,
            ‘type‘: ‘晴‘
        },
        ‘city‘: ‘北京‘,
        ‘forecast‘: [{
            ‘date‘: ‘17日星期天‘,
            ‘high‘: ‘高温 6℃‘,
            ‘fengli‘: ‘<![CDATA[<3级]]>‘,
            ‘low‘: ‘低温 -4℃‘,
            ‘fengxiang‘: ‘北风‘,
            ‘type‘: ‘晴‘
        }, {
            ‘date‘: ‘18日星期一‘,
            ‘high‘: ‘高温 4℃‘,
            ‘fengli‘: ‘<![CDATA[<3级]]>‘,
            ‘low‘: ‘低温 -3℃‘,
            ‘fengxiang‘: ‘南风‘,
            ‘type‘: ‘阴‘
        }, {
            ‘date‘: ‘19日星期二‘,
            ‘high‘: ‘高温 7℃‘,
            ‘fengli‘: ‘<![CDATA[<3级]]>‘,
            ‘low‘: ‘低温 -4℃‘,
            ‘fengxiang‘: ‘西南风‘,
            ‘type‘: ‘多云‘
        }, {
            ‘date‘: ‘20日星期三‘,
            ‘high‘: ‘高温 9℃‘,
            ‘fengli‘: ‘<![CDATA[<3级]]>‘,
            ‘low‘: ‘低温 -4℃‘,
            ‘fengxiang‘: ‘北风‘,
            ‘type‘: ‘晴‘
        }, {
            ‘date‘: ‘21日星期四‘,
            ‘high‘: ‘高温 11℃‘,
            ‘fengli‘: ‘<![CDATA[<3级]]>‘,
            ‘low‘: ‘低温 -3℃‘,
            ‘fengxiang‘: ‘西南风‘,
            ‘type‘: ‘晴‘
        }],
        ‘ganmao‘: ‘各项气象条件适宜，无明显降温过程，发生感冒机率较低。‘,
        ‘wendu‘: ‘-2‘
    },
    ‘status‘: 1000,
    ‘desc‘: ‘OK‘
} < class ‘dict‘ >

#coding=utf-8
import json
d1 = {‘name‘:‘foot‘}

‘‘‘
第一种写法
json.dump(d1,open(‘db‘,‘w‘))
d1 = json.load(open(‘db‘,‘r‘))
print(d1,type(d1))
‘‘‘

#第二种写法
with open("db","w") as f:
    json.dump(d1,f)

with open("db","r") as f:
    print(json.load(f))