【Python基础 day21】random & 序列化 & 异常处理 & Os

>>> import json
>>> dic = {‘k1‘:‘v1‘,‘k2‘:‘v2‘,‘k3‘:‘v3‘}
>>> str_dic = json.dumps(dic)
>>> print(type(str_dic),str_dic)
<class ‘str‘> {"k1": "v1", "k2": "v2", "k3": "v3"}
>>> dic2 = json.loads(str_dic)
>>> print(type(dic2),dic2)
<class ‘dict‘> {‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘, ‘k3‘: ‘v3‘}
>>> t1 = (1,2,3)
>>> str_dic = json.dumps(t1)#如果将元组序列化后，反序列化不能变成元组
>>> print(type(str_dic),str_dic)
<class ‘str‘> [1, 2, 3]
>>> dic2 = json.loads(str_dic)
>>> print(type(dic2),dic2)
<class ‘list‘> [1, 2, 3]
>>> t2= [1,2,3]
>>> str_dic = json.dumps(t2)
>>> print(type(str_dic),str_dic)
<class ‘str‘> [1, 2, 3]
>>> dic2 = json.loads(str_dic)
>>> print(type(dic2),dic2)
<class ‘list‘> [1, 2, 3]
>>> list_s = [1,[‘a‘,‘b‘,‘c‘],3,{‘k1‘:‘v1‘,‘k2‘:‘v2‘}]#可以处理多类型
>>> str_dic = json.dumps(list_s)
>>> print(type(str_dic),str_dic)
<class ‘str‘> [1, ["a", "b", "c"], 3, {"k1": "v1", "k2": "v2"}]
>>> s = {1,3,4,5}#序列化列表时报错
>>> str_dic = json.dumps(s)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python36\lib\json\__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "C:\Python36\lib\json\encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "C:\Python36\lib\json\encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "C:\Python36\lib\json\encoder.py", line 180, in default
    o.__class__.__name__)
TypeError: Object of type ‘set‘ is not JSON serializable

f = open("text.txt", ‘a‘)
dic = {"k1":1}
tu = (123,[1,2,3],{"1":23})
json.dump(dic, f)
json.dump(tu, f)
f.close()
f = open("text.txt")
dic2 = json.load(f)
dic3 = json.load(f)
f.close()
print(dic2)
print(dic3)

dic = {‘k1‘:‘v1‘,‘k2‘:‘v2‘,‘k3‘:‘v3‘}#
str_pic = pickle.dumps(dic)  #序列化到内存（字符串格式保存）
# print(str_pic,type(str_pic))
dic2 = pickle.loads(str_pic)
print(dic2,type(dic2))

# str_time = time.localtime(1000000000)
# f = open("times.txt","wb")
# pickle.dump(str_time,f)
# f.close()
f = open("times.txt","rb")
str_time = pickle.load(f)
print(str_time.tm_year)

f1 = shelve.open("shelve_file.txt")
# print(f1["key"])
f1["key"] = "this was not here before"
print(type(f1["key"]))#<class ‘str‘>
f1.close()

f1 = shelve.open("shelve_file.txt")
existing = f1["key"] #首先需要将读取的内容赋值给一个变量
f1.close()
print(existing)

f = shelve.open("shelve.txt",flag="r")#设置flag= “r”,代表只读，不支持多人同时写，但是可以同时读
tiems = f["key"]
f.close()
print(tiems)

#正常情况下shelve打开的文件句柄感知不到值的修改，设置writeback = True就可以保存修改内容了
import shelve
# f2 = shelve.open(‘shelve_file‘, writeback=True)
# print(f2[‘key‘])
# f2[‘key‘][‘new_value‘] = {1,2,3}
# f2.close()
# import shelve
f = shelve.open(‘shelve_file‘,flag=‘r‘)
print(f[‘key‘])
f.close()

f = shelve.open("shelve.txt",writeback=True)
ts = f["key"]
f.close()
print(ts)