dumps和loads方法都在內存中轉換，
dump和load的方法會多一個步驟，dump是把序列化後的字符串寫到一個文件中，而load是從一個文件中讀取字符串

將列表轉為字符串

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

將字典轉化為字符串

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

將字符串轉為列表

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

將字符串轉為字典

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

字符串轉字典

#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))

輸出

{
    "data": {
        
 
"yesterday": {
            "date": "16日星期六",
            "high": "高溫 3℃",
            "fx": "北風",
            "low": "低溫 -6℃",
            "fl": "<![CDATA[3-4級]]>",
            "type": "晴"
        },
        "city": "北京",
        "forecast": [{
            "date": "17日星期天",
            "high": "高溫 6℃",
            "fengli": "<![CDATA[<3級]]>",
            "low": "低溫 -4℃",
            "fengxiang": "北風",
            "type": "晴"
        }, {
            "date": "18日星期一",
            "high": "高溫 4℃",
            "fengli": "<![CDATA[<3級]]>",
            "low": "低溫 -3℃",
            "fengxiang": "南風",
            "type": "陰"
        }, {
            "date": "19日星期二",
            "high": "高溫 7℃",
            "fengli": "<![CDATA[<3級]]>",
            "low": "低溫 -4℃",
            "fengxiang": "西南風",
            "type": "多雲"
        }, {
            "date": "20日星期三",
            "high": "高溫 9℃",
            "fengli": "<![CDATA[<3級]]>",
            "low": "低溫 -4℃",
            "fengxiang": "北風",
            "type": "晴"
        }, {
            "date": "21日星期四",
            "high": "高溫 11℃",
            "fengli": "<![CDATA[<3級]]>",
            "low": "低溫 -3℃",
            "fengxiang": "西南風",
            "type": "晴"
        }],
        "ganmao": "各項氣象條件適宜，無明顯降溫過程，發生感冒機率較低。",
        "wendu": "-2"
    },
    "status": 1000,
    "desc": "OK"
} < class ‘str‘ > 

{
    ‘data‘: {
        ‘yesterday‘: {
            ‘date‘: ‘16日星期六‘,
            ‘high‘: ‘高溫 3℃‘,
            ‘fx‘: ‘北風‘,
            ‘low‘: ‘低溫 -6℃‘,
            ‘fl‘: ‘<![CDATA[3-4級]]>‘,
            ‘type‘: ‘晴‘
        },
        ‘city‘: ‘北京‘,
        ‘forecast‘: [{
            ‘date‘: ‘17日星期天‘,
            ‘high‘: ‘高溫 6℃‘,
            ‘fengli‘: ‘<![CDATA[<3級]]>‘,
            ‘low‘: ‘低溫 -4℃‘,
            ‘fengxiang‘: ‘北風‘,
            ‘type‘: ‘晴‘
        }, {
            ‘date‘: ‘18日星期一‘,
            ‘high‘: ‘高溫 4℃‘,
            ‘fengli‘: ‘<![CDATA[<3級]]>‘,
            ‘low‘: ‘低溫 -3℃‘,
            ‘fengxiang‘: ‘南風‘,
            ‘type‘: ‘陰‘
        }, {
            ‘date‘: ‘19日星期二‘,
            ‘high‘: ‘高溫 7℃‘,
            ‘fengli‘: ‘<![CDATA[<3級]]>‘,
            ‘low‘: ‘低溫 -4℃‘,
            ‘fengxiang‘: ‘西南風‘,
            ‘type‘: ‘多雲‘
        }, {
            ‘date‘: ‘20日星期三‘,
            ‘high‘: ‘高溫 9℃‘,
            ‘fengli‘: ‘<![CDATA[<3級]]>‘,
            ‘low‘: ‘低溫 -4℃‘,
            ‘fengxiang‘: ‘北風‘,
            ‘type‘: ‘晴‘
        }, {
            ‘date‘: ‘21日星期四‘,
            ‘high‘: ‘高溫 11℃‘,
            ‘fengli‘: ‘<![CDATA[<3級]]>‘,
            ‘low‘: ‘低溫 -3℃‘,
            ‘fengxiang‘: ‘西南風‘,
            ‘type‘: ‘晴‘
        }],
        ‘ganmao‘: ‘各項氣象條件適宜，無明顯降溫過程，發生感冒機率較低。‘,
        ‘wendu‘: ‘-2‘
    },
    ‘status‘: 1000,
    ‘desc‘: ‘OK‘
} < class ‘dict‘ >

將字典存入文件中，再從文件讀取出來

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

‘‘‘
第一種寫法
json.dump(d1,open(‘db‘,‘w‘))
d1 = json.load(open(‘db‘,‘r‘))
print(d1,type(d1))
‘‘‘

#第二種寫法
with open("db","w") as f:
    json.dump(d1,f)

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

參考：

http://www.cnblogs.com/bainianminguo/p/6676067.html

python的json模塊的dumps，loads，dump，load方法介紹