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

 1 #!/usr/bin/evn python
 2 # -*- coding:utf-8 -*-
 3 import json
 4 numbers = [2, 5, 3, 7, 11, 13]
 5 filename = "numbers.json"
 6 with open(filename, "w") as f:
 7     json.dump(numbers, f)
 8     
 9 """
10 json.dump(numbers, f)接受两个参数，存储数据和存储文件对像
11 """

 1 #!/usr/bin/evn python
 2 # -*- coding:utf-8 -*-
 3 import json
 4 filename = "numbers.json"
 5 with open(filename) as f:
 6     numbers = json.load(f)
 7     print(numbers)
 8 
 9 
10 输入结果：
11 [2, 5, 3, 7, 11, 13]

例子二

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

 1 #!/usr/bin/evn python
 2 # -*-coding:utf-8 -*-
 3 import json
 4 data = {
 5     "roles":[
 6         {"roles":"monster","type":"pig","life":50},
 7         {"roles":"hero","type":"关羽","life":80},
 8     ]
 9 }
10 d = json.dumps(data)  # 将数据类型转成字符串，序列化
11 print(d, type(d))
12 d2 = json.loads(d)  # 将字符串转成相应的数据类型，反序列化
13 print(d2["roles"], type(d2))
14 
15 
16 输入结果：
17 {"roles": [{"roles": "monster", "type": "pig", "life": 50}, {"roles": "hero", "type": "u5173u7fbd", "life": 80}]} <class 'str'>
18 
19 [{'roles': 'monster', 'type': 'pig', 'life': 50}, {'roles': 'hero', 'type': '关羽', 'life': 80}] <class 'dict'>