json模块

很多程序都要求用户输入某种信息，如让用户存储游戏首选项或提供要可视化的数据，程序都把用户提供的信息存储在列表和字典等数据结构中。用户关闭程序时，可以使用模块json来存储数据。

Json模块提供了四个功能：dumps、dump、loads、load

例子一

#!/usr/bin/evn python
# -*- coding:utf-8 -*-
import json
numbers = [2, 5, 3, 7, 11, 13]
filename = "numbers.json"
with open(filename, "w") as f:
    json.dump(numbers, f)
    
"""
json.dump(numbers, f)接受两个参数，存储数据和存储文件对像
"""

#!/usr/bin/evn python
# -*- coding:utf-8 -*-
import json
filename = "numbers.json"
with open(filename) as f:
    numbers = json.load(f)
    print(numbers)


输入结果：
[2, 5, 3, 7, 11, 13]

例子二

#!/urs/bin/evn python
# -*- coding:utf-8 -*-
import json
# 如果以前存储了用户名，就加载它
# 否则，就提示用户名输入用户名并存储它
filename = "username.json"
try:
    with open(filename) as f:
        username = json.load(f)
except FileNotFoundError:
    username = input("请输入用户名：")
    with open(filename, "w") as f:
        json.dump(username, f)
else:
    print("welcome back" + "	" + username)

#!/usr/bin/evn python
# -*-coding:utf-8 -*-
import json
data = {
    "roles":[
        {"roles":"monster","type":"pig","life":50},
        {"roles":"hero","type":"关羽","life":80},
    ]
}
d = json.dumps(data)  # 将数据类型转成字符串，序列化
print(d, type(d))
d2 = json.loads(d)  # 将字符串转成相应的数据类型，反序列化
print(d2["roles"], type(d2))


输入结果：
{"roles": [{"roles": "monster", "type": "pig", "life": 50}, {"roles": "hero", "type": "u5173u7fbd", "life": 80}]} <class 'str'>

[{'roles': 'monster', 'type': 'pig', 'life': 50}, {'roles': 'hero', 'type': '关羽', 'life': 80}] <class 'dict'>