python 物件持久化

print(open('persondb.dat','rb').read())

testdemo2.py

#讀取資料庫

#載入乙個例項的時候，類極其模組的檔案都必須匯入

#該類的例項再次載入的時候，對類的源**檔案的修改會自動選取

import testdemo

import shelve

db=shelve.open('persondb')

print(len(db))    #獲取資料條數 3

print(list(db.keys()))   #獲取資料鍵值 ['bob smith', 'sue jones', 'tom jones']

tom=db['tom jones']

print(tom)    #[manager: job=mgr, name=tom jones, pay=50000]

print(tom.lastname())    #jones

print(tom.pay)     #50000

for key in db.keys():

print(key, '=>', db[key])   #列印資料庫中所有資料

for key in sorted(db, reverse=true):

print(key, '=>', db[key])   #列印資料庫中所有資料，並且排序

db.close()

testdemo3.py

#更新shelve中的物件

import shelve

db=shelve.open('persondb')

sue=db['sue jones']

print(sue)    #[person: job=dev, name=sue jones, pay=10000],每次執行值都會儲存

sue.giveraist(1.1)

db['sue jones']=sue

print(sue)    #[person: job=dev, name=sue jones, pay=21000]   pay為最新的值,每次執行值都會變化

db.close()

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