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

 1 #!/usr/bin/python
 2 import json,pickle
 3 '''
 4 json -用于字符串 和 python数据类型间进行转换
 5 json 的操作 dump /dumps load /loads
 6 pickle-用于python特有的类型 和 python的数据类型间进行转换
 7 pickle模块提供了四个功能：dumps、dump、loads、load
 8 '''
 9 test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"}
10 x=json.dumps(test)
11 print(x)
12 print(json.loads(x))
13 #dumps 写入文件
14 with open('json_test','w',encoding='utf-8')as f:
15     f.write(json.dumps(test))
16 #
17 #
18 # # loads从文件读取
19 with open('json_test','r',encoding='utf-8') as f:
20     print(json.loads((f.read())))
21 
22 
23 
24 
25 #dump 写入文件
26 with open('json_test','w',encoding='utf-8')as f:
27     json.dump(test,f)
28 #
29 #
30 # # load 从文件读取
31 with open('json_test','r',encoding='utf-8') as f:
32     print(json.load((f)))

2.pickle

 1 #!/usr/bin/python
 2 import json,pickle
 3 test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"}
 4 #dump
 5 x=pickle.dumps(test)
 6 print(x)
 7 print(pickle.loads(x))
 8 
 9 with open('json_test.pk','wb')as f:
10     pickle.dump('test',f)
11 
12 #
13 # # load
14 with open('json_test.pk','rb') as f:
15     print(pickle.load((f)))

3.shelve

注意：打开文件后需要关闭文件

 1 #!/usr/bin/python
 2 # -*- coding: utf-8 -*-
 3 import pickle,shelve
 4 
 5 #shelve 写
 6 shelve_test=shelve.open('shelve_test')  #打开文件
 7 name = 'test'          #存字符串
 8 list_test=[1,2,3,4,5]  #存列表
 9 dict_test={"test_line1":"test_line1", "test_line2":"test_line2", "test_line3":"test_line3"} #存字典
10 
11 shelve_test['name']=name
12 shelve_test['dict_test']=dict_test   #添加的key为字符串
13 shelve_test['list_test']=list_test
14 
15 
16 #shelve 读出来
17 print(shelve_test.get('name'))
18 print(shelve_test.get('list_test'))
19 print(shelve_test.get('dict_test'))
20 shelve_test.close()