Python Serialization _json,pickle,shelve Module

Serialization of

Serialization refers to converting the data type in memory into a string so that it can be stored on the hard disk or transmitted over the network to the remote, because the hard disk or the network can only accept bytes

• Turns memory data into characters, called serialization
• Turn characters into memory data, called deserialization

Module Jsonjson.dumps () serializes an object

import jsondata = {    ‘roles‘:[        {‘role‘:‘monster‘,‘type‘:‘pig‘,‘life‘:50},        {‘role‘:‘hero‘,‘type‘:‘关羽‘,‘life‘:80},    ]}d = json.dumps(data) #转成字符串print(type(d))print(d)

Printing results:

<class ‘str‘>{"roles": [{"role": "monster", "type": "pig", "life": 50}, {"role": "hero", "type": "\u5173\u7fbd", "life": 80}]}

Json.lodads () Loading data from an object

import jsondata = {    ‘roles‘:[        {‘role‘:‘monster‘,‘type‘:‘pig‘,‘life‘:50},        {‘role‘:‘hero‘,‘type‘:‘关羽‘,‘life‘:80},    ]}d = json.dumps(data) #仅转成字符串d2 = json.loads(d)print(type(d2),d2) #<class ‘dict‘>#{‘roles‘: [{‘role‘: ‘monster‘, ‘type‘: ‘pig‘, ‘life‘: 50}, {‘role‘: ‘hero‘, ‘type‘: ‘关羽‘, ‘life‘: 80}]}

Json.dump () Serializes an object into a file

import jsondata = {    ‘roles‘:[        {‘role‘:‘monster‘,‘type‘:‘pig‘,‘life‘:50},        {‘role‘:‘hero‘,‘type‘:‘关羽‘,‘life‘:80},    ]}f = open(‘test.json‘,mode=‘w‘)json.dump(data, f) #转成字符并写入文件

Result: Data is written to the file

Json.load () loads data from an open file handle

import jsonf = open(‘test.json‘,‘r‘)data = json.load(f)print(data[‘roles‘])

Print:

[{‘role‘: ‘monster‘, ‘type‘: ‘pig‘, ‘life‘: 50}, {‘role‘: ‘hero‘, ‘type‘: ‘关羽‘, ‘life‘: 80}]

import jsonf = open(‘json_file.json‘,‘w‘,encoding=‘utf-8‘)data1 = {‘name‘:‘nurato‘,‘skill‘:‘螺旋丸‘}data2 = [1,2,3,‘sunshine‘]json.dump(data1, f)json.dump(data2, f)

Results:

Description: can dump multiple data and write to file

Let's do it now. json.load

f = open(‘json_file.json‘,‘r‘,encoding=‘utf-8‘)json.load(f)# 程序报错：json.decoder.JSONDecodeError

Load only once, and JSON format has a problem, will error

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Module Pickle

import pickledata1 = {‘name‘:‘nurato‘,‘skill‘:‘螺旋丸‘}f = open(‘data.pkl‘,‘wb‘)pickle.dump(data1,f)

Result: A file named Data.pkl was created

import picklef = open(‘data.pkl‘,‘rb‘)d = pickle.load(f)print(type(d))print(d)#<class ‘dict‘>#{‘name‘: ‘nurato‘, ‘skill‘: ‘螺旋丸‘}

About JSON and Pickle

Json:

Advantages: Cross-language, small size

Cons: Only support int\str\list\tuple\dict

Pickle:

Pros: Designed for Python and supports all Python data types

Cons: can only be used in Python, the storage data occupy large space

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Serialization of shelve modules

import shelvef = shelve.open(‘shelve_test‘) #打开一个文件names = [‘python‘, ‘html‘, ‘java‘]info = {‘name‘: ‘jack‘, ‘age‘: 25}f[‘names‘] = namesf[‘info_dic‘] = infof.close()

Result: The Shelve_test file is created

import shelvef = shelve.open(‘shelve_test‘) #打开一个文件print(list(f.keys()))  #[‘names‘, ‘info_dic‘]print(list(f.items())) #[(‘names‘, [‘python‘, ‘html‘, ‘java‘]), (‘info_dic‘, {‘name‘: ‘jack‘, ‘age‘: 25})]print(f.get(‘names‘)) #[‘python‘, ‘html‘, ‘java‘]print(f.get(‘info_dic‘)) #{‘name‘: ‘jack‘, ‘age‘: 25}

Add Content:

import shelvef = shelve.open(‘shelve_test‘) #打开一个文件f[‘book‘] = [1,2,3,4,5] #增加内容f.close()f2 = shelve.open(‘shelve_test‘)print(list(f2.keys()))  # [‘names‘, ‘info_dic‘, ‘book‘]print(f2[‘book‘])

Let's modify the content: (Only through f[‘book‘] = [1,2,‘肖申克的救赎‘,4,5] ) re-assigning values in such a way as to change

f[‘book‘][0] = ‘new book‘Such a way is not possible.

import shelvef = shelve.open(‘shelve_test‘)  # 打开一个文件f[‘book‘] = [1,2,‘肖申克的救赎‘,4,5]f.close()f2 = shelve.open(‘shelve_test‘)print(f2[‘book‘])  # [1, 2, ‘肖申克的救赎‘, 4, 5]

Delete content:

import shelvef = shelve.open(‘shelve_test‘) #打开一个文件del f[‘book‘]f.close()f2 = shelve.open(‘shelve_test‘)print(list(f2.items())) # 打印 ： [(‘names‘, [‘python‘, ‘html‘, ‘java‘]), (‘info_dic‘, {‘name‘: ‘jack‘, ‘age‘: 25})]

Python Serialization _json,pickle,shelve Module