import json

dumps 将对象转换成字符串(序列化)
lst = [1,2,3,4,5]
print(repr(json.dumps(lst)))
# "[1,2,3,4,5]"

loads 将字符串转换成对象(反序列化)
str_lst = ‘[1, 2, 3, 4, 5]‘
lst = json.loads(str_lst)
print(repr(lst))
# [1,2,3,4,5]
特例:
dic = {"k1":"名字"}
str_dic = json.dumps(dic)
print(str_dic)
# {"k1": "\u540d\u5b57"}
解决方法:
dic = {"k1":"名字"}
str_dic = json.dumps(dic,ensure_ascii=False)
print(str_dic)
# {"k1": "名字"}
# ensure_ascii=False 关闭ascii码

dump 将对象转换成字符串写入文件当中(序列化)
import json
lst = [1,2,3,4,5,6]
with open("info","w",encoding="utf-8")as f:
    json.dump(lst,f)
# info文件中写入一行[1,2,3,4,5,6]

load 将文件中的字符串转换成对象(反序列化)
import json
lst = [1,2,3,4,5,6]
with open("info","r",encoding="utf-8")as f:
    lst1 = json.load(f)
    print(lst1)
# [1,2,3,4,5,6] 

with open("info","r",encoding="utf-8")
for i in f:
    l = json.loads(i)
    print(l)

对象转换成类似字节
import pickle
lst = [1,2,3,4,5]
b_lst = pickle.dumps(lst)
print(b_lst)
# b‘\x80\x03]q\x00(K\x01K\x02K\x03K\x04K\x05e.‘

类似字节转换成对象
import pickle
lst = [1,2,3,4,5]
b_lst = pickle.dumps(lst)
t_lst = pickle.loads(b_lst)
print(t_lst)
# [1,2,3,4,5]

将对象转换成乱码写入对象
import pickle 
dic = {"user":"baoyuan"}
pickle.dump(dic,open("info","wb"))
# ?}q X   userqX   baoyuanqs.

将乱码转换成对象输出
import pickle 
dic = {"user":"baoyuan"}
pickle.dump(dic,open("info","wb"))
print(pickle.load(open("info","rb")))
# {‘user‘: ‘baoyuan‘}

import pickle
dic = {"1":2}
with open("info","wb")as f:
    s = "\n".encode("utf-8")
    f.write(pickle.dumps(dic) + s)
    f.write(pickle.dumps(dic) + s)
    f.write(pickle.dumps(dic) + s)

import pickle
dic = {"1":2}
with open("info","wb")as f:
    s = "\n".encode("utf-8")
    f.write(pickle.dumps(dic) + s)
    f.write(pickle.dumps(dic) + s)
    f.write(pickle.dumps(dic) + s)

f1 = open("info","rb")
for i in f1:
    print(pickle.loads(i))

当前工作路径 ***
print(os.getcwd())

路径切换    **
os.chdir(r"D:\pycharm demo\123")

当前目录
print(os.curdir)

父级目录
print(os.pardir)

import os   
创建一个文件夹    ***
os.mkdir("ttt")

删除一个文件夹    ***
os.rmdir("ttt")

递归创建文件夹    ***
os.makedirs("ttt/sss/ddd/ee")

递归删除文件夹    ***
os.removedirs("ttt/sss/ddd/ee")

获取当前文件夹下所有文件名 ***
print(os.listdir())

import os

修改名字     ***
os.rename("123","info")

删除文件     ***
os.remove("info")

import os

通过相对路径获取绝对路径   ***
print(os.path.abspath("info"))

将路径以最后一个"\"切割(路径,文件名)
print(os.path.split(os.path.abspath("info")))

获取路径        ***
print(os.path.dirname("D:\pycharm demo\info"))
                      
获取文件名       **
print(os.path.basename("D:\pycharm demo\info"))

判断路径是否存在    ***
print(os.path.exists("D:\pycharm demo\info"))

判断是不是路径     ***
print(os.path.isdir(r"D:\pycharm demo"))

判断是不是文件名   ***
print(os.path.isfile("info"))

判断是不是绝对路径  ***
print(os.path.isabs("D:\pycharm demo\info"))

路径拼接         *****
print(os.path.join("D:\\","pycharm demo","info"))

文件最后修改的时间(返回时间戳)
print(os.path.getatime("D:\pycharm demo\info"))

文件最后的访问时间(返回时间戳)
print(os.path.getctime("D:\pycharm demo\info"))
print(os.path.getmtime("D:\pycharm demo\info"))

获取当前文件的大小(返回字节b)     ***
print(os.path.getsize("D:\pycharm demo\代码练习.py"))

import sys

脚本本身,当前文件运行(返回一个绝对路径)   ***
print(sys.argv)

退出程序，正常退出时exit(0),错误退出sys.exit(1)
print(sys.exit(n))

获取解释器版本
print(sys.version)

添加自定义模块查找路径
print(sys.path)

区分操作系统然后进行相关逻辑操作
print(sys.platform)

md5示例:
import hashlib
md5 = hashlib.md5()
md5.update("alex123".encode("utf-8"))
print(md5.hexdigest())

sha1示例:
import hashlib
sha1 = hashlib.sha1()
sha1.update("alex123".encode("utf-8"))
print(sha1.hexdigest())

最常用的是md5但是被中国人破解
平时加密的时候使用sha1

import hashlib
md5 = hashlib.md5("alex".encode("utf-8"))
md5.update("wusir".encode("utf-8"))
print(md5.hexdigest())

user = input("user")
pwd = input("pwd")
import hashlib
md5 = hashlib.md5(user.encode("utf-8"))
md5.update(pwd.encode("utf-8"))
print(md5.hexdigest())

import hashlib
ss = "baoyuanwusirtaibai"
s = "baoyuan"
s1 = "wusir"
s2 = "taibai"
md5 = hashlib.md5()
md5.update(ss.encode("utf-8"))
print(md5.hexdigest())

import hashlib
ss = "baoyuanwusirtaibai"
s = "baoyuan"
s1 = "wusir"
s2 = "taibai"
md5 = hashlib.md5()
md5.update(s.encode("utf-8"))
md5.update(s1.encode("utf-8"))
md5.update(s2.encode("utf-8"))
print(md5.hexdigest())
# 拼接加密 和 分解加密 的加密结果一样

# 生成可以使用名字来访问元素内容的tuple
from collections import namedtuple
point = namedtuple("tu",["a","b","c"])     # 第一个参数是元组的名字,第二参数是元组中元素的[名字,名字]
p = point({"key":(1,2,3,4)},20,10)
print(p)
# tu(a={‘key‘: (1, 2, 3, 4)}, b=20, c=10)

# 双端队列,可以快速的从另外一端追加和推出对象
from collections import deque
lst = deque([1,2,3,4,5,6])
lst.append(8)
lst.appendleft(0)
print(lst)
# deque([0,1,2,3,4,5,6,8])

lst = deque([1,2,3,4,5,6])
lst.pop()
lst.popleft()
print(lst)
# deque([2,3,4,5])

# 队列:先进先出
# 栈:先进后出 -- 栈顶

c = Counter(‘abcdeabcdabcaba‘)
print(c)
# Counter({‘a‘: 5, ‘b‘: 4, ‘c‘: 3, ‘d‘: 2, ‘e‘: 1})

from collections import defaultdict
dic = defaultdict(list)
dic["k1"].append(12)
print(dic)
# defaultdict(<class ‘list‘>, {‘k1‘: [12]})