json&&pickl&&shelve
阿新 • • 發佈:2019-05-06
get const elf 語言 bin sof python cor 修改 1.序列化&反序列化
序列化:把內存中的數據類型轉換為字符串,以便能夠存儲到硬盤或通過網絡傳輸到遠程,因為硬盤或網絡傳輸時只能接受bytes。
反序列化:把硬盤中的數據轉換為內存數據類型
#!/usr/bin/env python # -*- coding:utf-8 -*- # Author: vita data = {"haha":"哈哈"} fw = open(file="寫文件.txt",mode="w",encoding="utf-8") fw.write(str(data)) # 序列化 fw.close() fr = open(file="寫文件.txt",mode="r",encoding="utf-8") d = fr.read() d = eval(d) # 反序列化 print(d) fr.close() E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py {‘haha‘: ‘哈哈‘} Process finished with exit code 0
2.json
優點:跨語言、體積小
缺點:只能支持int\str\list\tuple\dict
- json.dumps()序列化為字符串,就不需要手動使用str()轉換為字符串然後再保存到文件中了,但並不把內容保存到硬盤中
#!/usr/bin/env python # -*- coding:utf-8 -*- # Author: vita import json data = {"haha":"哈哈"} # dumps並沒有把內容寫入到硬盤中 d = json.dumps(data) print(d,type(d)) E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py {"haha": "\u54c8\u54c8"} <class ‘str‘> Process finished with exit code 0
- json.loads()反序列化為其實際數據類型,就不需要使用eval()把內存中數據轉換為相應的數據類型了
#!/usr/bin/env python # -*- coding:utf-8 -*- # Author: vita import json data = {"haha":"哈哈"} # dumps並沒有把內容寫入到硬盤中 d = json.dumps(data) d2 = json.loads(d) print(d2,type(d2)) E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py {‘haha‘: ‘哈哈‘} <class ‘dict‘> Process finished with exit code 0
- json.dump()序列化,並保存到文件中
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import json
data = {"haha":"哈哈"}
fw = open(file="寫文件.txt",mode="w",encoding="utf-8")
d = json.dump(data,fw)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
Process finished with exit code 0
查看文件中的內容
{"haha": "\u54c8\u54c8"}
- json.load()反序列化,從文件中讀取內容,轉為實際的數據類型
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import json
data = {"haha":"哈哈"}
fr = open(file="寫文件.txt",mode="r",encoding="utf-8")
d = json.load(fr)
print(d,type(d))
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
{‘haha‘: ‘哈哈‘} <class ‘dict‘>
Process finished with exit code 0
- 嘗試多次dump
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import json
data = {"haha":"哈哈"}
data2 = {"hehe":"呵呵"}
fw = open(file="寫文件.json",mode="w",encoding="utf-8")
json.dump(data,fw)
json.dump(data2,fw)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
Process finished with exit code 0
查看文件內容
{"haha": "\u54c8\u54c8"}{"hehe": "\u5475\u5475"}
多次dump是沒有報錯,但是load()
- 多次dump()後load()
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import json
data = {"haha":"哈哈"}
data2 = {"hehe":"呵呵"}
fr = open(file="寫文件.json",mode="r",encoding="utf-8")
print(json.load(fr))
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
Traceback (most recent call last):
File "E:/PythonProject/python-test/BasicGrammer/test.py", line 8, in <module>
print(json.load(fr))
File "D:\software2\Python3\install\lib\json\__init__.py", line 299, in load
parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
File "D:\software2\Python3\install\lib\json\__init__.py", line 354, in loads
return _default_decoder.decode(s)
File "D:\software2\Python3\install\lib\json\decoder.py", line 342, in decode
raise JSONDecodeError("Extra data", s, end)
json.decoder.JSONDecodeError: Extra data: line 1 column 25 (char 24)
Process finished with exit code 1
"說明不要dump多次,雖然dump不報錯,但是load不回來了。因為在一行有兩種類型的數據"
3.pickle
優點:轉為python設計,支持python所有數據類型。
缺點:只能在python中使用,存儲數據占用空間大。
- dumps&loads
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import pickle
data = {"haha":"哈哈"}
d = pickle.dumps(data)
print(d,type(d))
l = pickle.loads(d)
print(l,type(l))
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
b‘\x80\x03}q\x00X\x04\x00\x00\x00hahaq\x01X\x06\x00\x00\x00\xe5\x93\x88\xe5\x93\x88q\x02s.‘ <class ‘bytes‘>
{‘haha‘: ‘哈哈‘} <class ‘dict‘>
Process finished with exit code 0
- dump()&load()
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import pickle
data = {"haha":"哈哈"}
fw = open(file="寫文件.json",mode="wb") #由於dump後數據類型是bytes類型,所以mode="wb"
d = pickle.dump(data,fw)
fw.close()
fr = open(file="寫文件.json",mode="rb") #寫入時是wb,讀取時是rb
l = pickle.load(fr)
print(l,type(l))
fr.close()
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
{‘haha‘: ‘哈哈‘} <class ‘dict‘>
Process finished with exit code 0
- 函數也可被序列化
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import pickle
def fun():
print("232")
d = pickle.dumps(fun)
print(d,type(d))
l = pickle.loads(d)
print(l,type(l))
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
b‘\x80\x03c__main__\nfun\nq\x00.‘ <class ‘bytes‘>
<function fun at 0x00000157C0883E18> <class ‘function‘>
Process finished with exit code 0
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import pickle
def fun():
print("232")
fw = open(file="寫文件.json",mode="wb")
d = pickle.dump(fun,fw)
fw.close()
fr = open(file="寫文件.json",mode="rb")
l = pickle.load(fr)
print(l,type(l))
fr.close()
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
<function fun at 0x0000017668504C80> <class ‘function‘>
Process finished with exit code 0
4.shelve
可序列化多次,反序列化多次,就像操作字典一樣操作數據
shelve是一個簡單的k,v將內存數據通過文件持久化的模塊,可以持久化任何pickle可支持的python數據格式
"註意:shelve打開文件時,文件如果是存在的,是會報下面的錯誤的"
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
Traceback (most recent call last):
File "E:/PythonProject/python-test/BasicGrammer/test.py", line 5, in <module>
f = shelve.open("寫文件.txt")
File "D:\software2\Python3\install\lib\shelve.py", line 243, in open
return DbfilenameShelf(filename, flag, protocol, writeback)
File "D:\software2\Python3\install\lib\shelve.py", line 227, in __init__
Shelf.__init__(self, dbm.open(filename, flag), protocol, writeback)
File "D:\software2\Python3\install\lib\dbm\__init__.py", line 88, in open
raise error[0]("db type could not be determined")
dbm.error: db type could not be determined
Process finished with exit code 1
"shelve序列化"
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import shelve
f = shelve.open("寫文件.txt") #此處的文件不能是已經存在的
names = ["vita","麗麗","lyly"]
info = {"name":"vita","age":23}
f["names"]=names
f["info_dic"]=info
f.close()
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
Process finished with exit code 0
寫入成功後,產生如下的文件
"shelve反序列化"
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
import shelve
f = shelve.open("寫文件.txt")
print(f["names"])
print(f["info_dic"])
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
[‘vita‘, ‘麗麗‘, ‘lyly‘]
{‘name‘: ‘vita‘, ‘age‘: 23}
Process finished with exit code 0
- shelve相關操作
"查詢"
>>> f = shelve.open("寫文件.txt")
>>> f
<shelve.DbfilenameShelf object at 0x000002A52DB5E780>
>>> f.keys()
KeysView(<shelve.DbfilenameShelf object at 0x000002A52DB5E780>)
>>> list(f.keys())
[‘names‘, ‘info_dic‘]
>>> list(f.items())
[(‘names‘, [‘vita‘, ‘麗麗‘, ‘lyly‘]), (‘info_dic‘, {‘name‘: ‘vita‘, ‘age‘: 23})]
>>> f.get("names")
[‘vita‘, ‘麗麗‘, ‘lyly‘]
>>> f.get("info_dic")
{‘name‘: ‘vita‘, ‘age‘: 23}
>>> f["names"][1]
‘麗麗‘
"修改"
>>> f["names"][1]="超超" #這樣修改是不可以的
>>> f["names"][1] "
‘麗麗‘
>>> f["names"]=["ccc","lll"] #可以這樣修改
>>> f["names"]
[‘ccc‘, ‘lll‘]
>>> f.items()
ItemsView(<shelve.DbfilenameShelf object at 0x000002A52DB5E780>)
>>> list(f.items())
[(‘names‘, [‘ccc‘, ‘lll‘]), (‘info_dic‘, {‘name‘: ‘vita‘, ‘age‘: 23})]
"刪除"
>>> del f["names"]
>>> list(f.items())
[(‘info_dic‘, {‘name‘: ‘vita‘, ‘age‘: 23})]
"增加"
>>> f["scores"]=[90,89]
>>> list(f.items())
[(‘info_dic‘, {‘name‘: ‘vita‘, ‘age‘: 23}), (‘scores‘, [90, 89])]
json&&pickl&&shelve