python成长之路15——json pickle time log

一. 序列化模块——json和pickle

      序列化：  将python的数据类型序列化成字符串或者bytes类型

　　反序列化：将字符串或者bytes类型反序列化成python的数据类型

      注意：在python里单引号和双引号是没有区别的，但是在别的语言里，单引号是用来引字符的，双引号是用来引字符串的。所以如果我们的字符串写成这样："['alex','aric']"要和别的语言做交互的时候是有问题的。所以我们要保证必须：外面是单引号，里面是双引号。

import json

li1=["alex","aric","jack"]
s1=json.dumps(li1)
print(s1,type(s1))

s2='{"k1":"v1","k2":"v2"}'
dic=json.loads(s2)
print(dic,type(dic))

执行结果：
["alex", "aric", "jack"] <class 'str'>
{'k2': 'v2', 'k1': 'v1'} <class 'dict'>

import json

li1=["alex","aric","jack","你好"]
json.dump(li1,open("db","w",encoding="utf8"))

ret=json.load(open("db","r+",encoding="utf8"))
print(ret,type(ret))
#dump和load不仅可以序列化，还可以实现写入文件和从文件读出

执行结果：
['alex', 'aric', 'jack', '你好'] <class 'list'>

import pickle
li1=["alex","aric",123]
ret=pickle.dumps(li1)
print(ret,type(ret))
#pickle序列化成的是bytes类型

li2=pickle.loads(ret)
print(li2,type(li2))

执行结果：
b'\x80\x03]q\x00(X\x04\x00\x00\x00alexq\x01X\x04\x00\x00\x00aricq\x02K{e.' <class 'bytes'>
['alex', 'aric', 123] <class 'list'>

import pickle
dic={"k1":"v1","k2":"v2","k3":"你好"}
pickle.dump(dic,open("db","wb"))
#因为pickle要序列化成bytes类型,所以写入和读出的时候必须加"b"

ret=pickle.load(open("db","rb"))
print(ret)

json和pickle的区别：

(1) json可以跨语言跨平台使用；

     json只能处理基本的数据类型：dict,list,tuple,str,int,float,True,False,None

(2) pickle只能在python里使用，而且对python的版本可能有要求，py2里pickle序列化的数据可能py3打不开；

     pickle支持任何数据类型，例如：玩儿游戏的时候，我们要存档（复杂的数据类型），就只能用pickle啦；

二. 时间模块time&datetime    

#_*_coding:utf-8_*_
__author__ = 'Alex Li'

import time
# print(time.clock()) #返回处理器时间,3.3开始已废弃 , 改成了time.process_time()测量处理器运算时间,不包括sleep时间,不稳定,mac上测不出来
# print(time.altzone)  #返回与utc时间的时间差,以秒计算\
# print(time.asctime()) #返回时间格式"Fri Aug 19 11:14:16 2016",
# print(time.localtime()) #返回本地时间 的struct time对象格式
# print(time.gmtime(time.time()-800000)) #返回utc时间的struc时间对象格式

# print(time.asctime(time.localtime())) #返回时间格式"Fri Aug 19 11:14:16 2016",
#print(time.ctime()) #返回Fri Aug 19 12:38:29 2016 格式, 同上

# 日期字符串 转成  时间戳
# string_2_struct = time.strptime("2016/05/22","%Y/%m/%d") #将 日期字符串 转成 struct时间对象格式
# print(string_2_struct)
# #
# struct_2_stamp = time.mktime(string_2_struct) #将struct时间对象转成时间戳
# print(struct_2_stamp)

#将时间戳转为字符串格式
# print(time.gmtime(time.time()-86640)) #将utc时间戳转换成struct_time格式
# print(time.strftime("%Y-%m-%d %H:%M:%S",time.gmtime()) ) #将utc struct_time格式转成指定的字符串格式

#时间加减
import datetime

# print(datetime.datetime.now()) #返回 2016-08-19 12:47:03.941925
#print(datetime.date.fromtimestamp(time.time()) )  # 时间戳直接转成日期格式 2016-08-19
# print(datetime.datetime.now() )
# print(datetime.datetime.now() + datetime.timedelta(3)) #当前时间+3天
# print(datetime.datetime.now() + datetime.timedelta(-3)) #当前时间-3天
# print(datetime.datetime.now() + datetime.timedelta(hours=3)) #当前时间+3小时
# print(datetime.datetime.now() + datetime.timedelta(minutes=30)) #当前时间+30分

#
# c_time  = datetime.datetime.now()
# print(c_time.replace(minute=3,hour=2)) #时间替换

Directive	Meaning	Notes
%a	Locale’s abbreviated weekday name.
%A	Locale’s full weekday name.
%b	Locale’s abbreviated month name.
%B	Locale’s full month name.
%c	Locale’s appropriate date and time representation.
%d	Day of the month as a decimal number [01,31].
%H	Hour (24-hour clock) as a decimal number [00,23].
%I	Hour (12-hour clock) as a decimal number [01,12].
%j	Day of the year as a decimal number [001,366].
%m	Month as a decimal number [01,12].
%M	Minute as a decimal number [00,59].
%p	Locale’s equivalent of either AM or PM.	(1)
%S	Second as a decimal number [00,61].	(2)
%U	Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.	(3)
%w	Weekday as a decimal number [0(Sunday),6].
%W	Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.	(3)
%x	Locale’s appropriate date representation.
%X	Locale’s appropriate time representation.
%y	Year without century as a decimal number [00,99].
%Y	Year with century as a decimal number.
%z	Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59].
%Z	Time zone name (no characters if no time zone exists).
%%	A literal '%' character.

 

三. 日志模块

python的logging模块提供了标准的日志接口，可以通过它存储各种格式的日志，logging的日志可以分为debug，info，warning，error，critical5个级别(level)，默认的level为warning。

import logging

logging.debug("debug")
logging.info("info")
logging.warning("warning")
logging.error("error")
logging.critical("critical")

执行结果：
WARNING:root:warning
ERROR:root:error
CRITICAL:root:critical

import logging

#输出level对应的日志级别
print(logging._levelToName)
#basicConfig对logging进行一些设置
logging.basicConfig(filename='log.log',  #设置输出到文件,默认输出到console
                    format='%(asctime)s - %(name)s - %(levelname)s -%(module)s:  %(message)s', #设置日志输出格式
                    datefmt='%Y-%m-%d %H:%M:%S %p', #设置时间格式
                    level=0, #设置日志级别,0为不设置,则级别为debug
                    )

logging.debug("debug")
logging.info("info")
logging.warning("warning")
logging.error("error")
logging.critical("critical")

执行结果：
终端：
{0: 'NOTSET', 50: 'CRITICAL', 20: 'INFO', 40: 'ERROR', 10: 'DEBUG', 30: 'WARNING'}
文件log.log：
2017-03-03 17:56:09 PM - root - DEBUG -func:  debug
2017-03-03 17:56:09 PM - root - INFO -func:  info
2017-03-03 17:56:09 PM - root - WARNING -func:  warning
2017-03-03 17:56:09 PM - root - ERROR -func:  error
2017-03-03 17:56:09 PM - root - CRITICAL -func:  critical

还可以这样写：logging.log(30,'log')  #30为level，
执行结果为：  WARNING:root:log

日志输出格式：