python模块之json序列化

31、序列化：

     1、json实现序列化,json.dumps()和json.loads()。

          >>> s1 = {'k1':'v1','k2':'v2'}

>>> import json

>>> json.dumps(s1)

'{"k1": "v1", "k2": "v2"}'

>>> s2 = json.dumps(s1)

>>> type(s2)

<class 'str'>

>>> json.loads(s2)

{'k1': 'v1', 'k2': 'v2'}

>>> type(json.loads(s2))

<class 'dict'>

2、注意：反序列化时要用双引号“”才行。

     #1：>>> dic1 = "{'key1':'v1','key2':'v2'}"

>>> ret2 = json.loads(dic1)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/usr/local/python3/lib/python3.5/json/__init__.py", line 319, in loads

    return _default_decoder.decode(s)

  File "/usr/local/python3/lib/python3.5/json/decoder.py", line 339, in decode

    obj, end = self.raw_decode(s, idx=_w(s, 0).end())

  File "/usr/local/python3/lib/python3.5/json/decoder.py", line 355, in raw_decode

    obj, end = self.scan_once(s, idx)

json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

#2：>>> dic2 = "["alex","xiao"]" 都用双引号“”也会报错。

  File "<stdin>", line 1

    dic2 = "["alex","xiao"]"

                 ^

SyntaxError: invalid syntax

>>> dic2 = '["alex","xiao"]' 可以

3、 dump（）和load（）的使用     

          >>> l1 = [11,22,33]

>>> json.dump(l1,open('/opt/a.txt','w'))

[root@bogon opt]# cat a.txt

[11, 22, 33]

     >>> l2 = json.load(open("/opt/a.txt","r"))

>>> print(l2,type(l2))

[11, 22, 33] <class 'list'>