二十六、python中json学习

1.json序列介绍：提供4个关键字：dumps，dump，loads，load（与pickle用法完全相同）

　　语法：f.write(bytes（json.dumps(dict)，encoding="utf-8"）)

　　　　　r=json.loads(f.read().decode("utf-8"))

　　将字典存入文件，由于字典格式不能转化成字节格式的，所以引入json

　　A.将一个字典转化成json序列存入一个文件

import json
 
accounts={
    1000:{
        'name':'Tom',
        'email':'22016311@qq.com',
        'passwd':'abc123',
        'balance':20000,
        'phone':'44165465',
        'bank_acc':{
            'ICBC':165116161,
            'CBC':16516516516,
            'ABC':656151616516
        }
    },
1001:{
        'name':'Tom1',
        'email':'220116311@qq.com',
        'passwd':'abc1123',
        'balance':210000,
        'phone':'441654165',
        'bank_acc':{
            'ICBC':16511161611,
            'CBC':165165165161,
            'ABC':6561516165161
        }
    }
}
 
print (json.dumps(accounts))   #将字典转成json序列
f=open("account.db","wb")        #写入文件account.db
f.write(bytes(json.dumps(accounts),encoding="utf-8"))  #写入文件account.db

f.close()
-------------------------------------------------------------------
{"1000": {"name": "Tom", "email": "22016311@qq.com", "passwd": "abc123", "balance": 20000, "phone": "44165465", "bank_acc": {"ICBC": 165116161, "CBC": 16516516516, "ABC": 656151616516}}, "1001": {"name": "Tom1", "email": "220116311@qq.com", "passwd": "abc1123", "balance": 210000, "phone": "441654165", "bank_acc": {"ICBC": 16511161611, "CBC": 165165165161, "ABC": 6561516165161}}}

　　B.重新创建一个新的python文件读取account.db中的内容：

import pickle
 
account_file=open("account.db","rb")                   #打开文件
account_dict=json.loads(account_file.read().decode("utf-8"))         #以json加载文件
#print (account_dict)
account_file.close()
#print(type(account_dict['1000']['balance']))             
account_dict['1000']['balance'] -= 500                   #取字典中balance然后减500
print (account_dict)
 
f=open("account.db","wb")
f.write(bytes(json.dumps(account_dict),encoding="utf-8"))  #将变更后的内容dumps入文件
f.close()
print (account_dict)
-----------------------------------------------------------------------------

{'1000': {'name': 'Tom', 'email': '22016311@qq.com', 'passwd': 'abc123', 'balance': 20000, 'phone': '44165465', 'bank_acc': {'ICBC': 165116161, 'CBC': 16516516516, 'ABC': 656151616516}}, '1001': {'name': 'Tom1', 'email': '220116311@qq.com', 'passwd': 'abc1123', 'balance': 210000, 'phone': '441654165', 'bank_acc': {'ICBC': 16511161611, 'CBC': 165165165161, 'ABC': 6561516165161}}}
{'1000': {'name': 'Tom', 'email': '22016311@qq.com', 'passwd': 'abc123', 'balance': 19500, 'phone': '44165465', 'bank_acc': {'ICBC': 165116161, 'CBC': 16516516516, 'ABC': 656151616516}}, '1001': {'name': 'Tom1', 'email': '220116311@qq.com', 'passwd': 'abc1123', 'balance': 210000, 'phone': '441654165', 'bank_acc': {'ICBC': 16511161611, 'CBC': 165165165161, 'ABC': 6561516165161}}}
{'1000': {'name': 'Tom', 'email': '22016311@qq.com', 'passwd': 'abc123', 'balance': 19500, 'phone': '44165465', 'bank_acc': {'ICBC': 165116161, 'CBC': 16516516516, 'ABC': 656151616516}}, '1001': {'name': 'Tom1', 'email': '220116311@qq.com', 'passwd': 'abc1123', 'balance': 210000, 'phone': '441654165', 'bank_acc': {'ICBC': 16511161611, 'CBC': 165165165161, 'ABC': 6561516165161}}}