python之常用标准库-json/pickle/shelve

json，用于各个平台语言的字符串 和 python数据类型间进行转换

json的方法：dumps,loads,dump,load

pickle-用于python特有的类型(字符串，列表，字典，集合等) 和 python的数据类型间进行转换

pickle的方法：dumps,loads,dump,load，但是都是以二进制存储

shelve，是一个简单的k,v将内存数据通过文件持久化的模块，可以持久化任何pickle可支持的python数据格式#添加的key为字符串

1.json

#!/usr/bin/python
import json,pickle
'''
json -用于字符串 和 python数据类型间进行转换
json 的操作 dump /dumps load /loads
pickle-用于python特有的类型 和 python的数据类型间进行转换
pickle模块提供了四个功能：dumps、dump、loads、load
'''
test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"}
x=json.dumps(test)
print(x)
print(json.loads(x))
#dumps 写入文件
with open('json_test','w',encoding='utf-8')as f:
    f.write(json.dumps(test))
#
#
# # loads从文件读取
with open('json_test','r',encoding='utf-8') as f:
    print(json.loads((f.read())))




#dump 写入文件
with open('json_test','w',encoding='utf-8')as f:
    json.dump(test,f)
#
#
# # load 从文件读取
with open('json_test','r',encoding='utf-8') as f:
    print(json.load((f)))

2.pickle

#!/usr/bin/python
import json,pickle
test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"}
#dump
x=pickle.dumps(test)
print(x)
print(pickle.loads(x))

with open('json_test.pk','wb')as f:
    pickle.dump('test',f)

#
# # load
with open('json_test.pk','rb') as f:
    print(pickle.load((f)))

3.shelve

注意：打开文件后需要关闭文件

#!/usr/bin/python
# -*- coding: utf-8 -*-
import pickle,shelve

#shelve 写
shelve_test=shelve.open('shelve_test')  #打开文件
name = 'test'          #存字符串
list_test=[1,2,3,4,5]  #存列表
dict_test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"} #存字典

shelve_test['name']=name
shelve_test['dict_test']=dict_test   #添加的key为字符串
shelve_test['list_test']=list_test


#shelve 读出来
print(shelve_test.get('name'))
print(shelve_test.get('list_test'))
print(shelve_test.get('dict_test'))
shelve_test.close()