Day 30 - 错误、异常与 JSON 数据 - Python学习笔记

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Day 30 - Errors, Exceptions and JSON Data

228. Catch Exceptions

try：Something that might cause an exception 可能引发异常的代码
except：Do this if there was an exception 发生异常时执行的代码
else：Do this if there were no exceptions 没有异常时执行的代码
finally：Do this no matter what happens 不管有没有异常都会执行的代码

try:  file = open("file.txt", "r", encoding="utf-8")  content = file.read()  
except FileNotFoundError:print("File was not found, creating a new file.")file = open("file.txt", "w", encoding="gbk")  file.write("你好")  
except UnicodeDecodeError as e:  print(f"Encoding error: {e}")  
else:  print(f"File content: {content}")  
finally: print("File was closed.")file.close()   

229. Raise Exceptions

height = float(input("Height (m): "))  
weight = float(input("Weight (kg): "))  if height > 3:  raise ValueError("Human Height should not be over 3 meters.")  bmi = weight / height ** 2  
print(bmi)

230. Improve the NATO Alphabet Project

NATO Alphabet Project

import pandas  df = pandas.read_csv("nato_phonetic_alphabet.csv")  
phonetic_dict = {row.letter: row.code for index, row in df.iterrows()}  
print(phonetic_dict)  def generate_alphabet():  word = input("Enter a word: ").upper()  try:  output_list = [phonetic_dict[letter] for letter in word]  except KeyError:  print("Sorry, only letters in the alphabet please.")  generate_alphabet()  else:  print(output_list)  generate_alphabet()

231. Read and Write JSON Data

Python JSON Module

import json        # JavaScript Object Notation  JavaScript对象表示法# Read JSON Data (JSON String -> Python Object)  
json_str = '{"name":"John", "age":30, "city":"New York"}'  
data = json.loads(json_str)  
print(data)  # Write JSON Data (Python Object -> JSON String)  
data = {  "name": "John",  "age": 30,  "city": "New York"  
}  
json_str = json.dumps(data, indent=4)  
print(json_str) # Read JSON Data (JSON File -> Python Object)  
with open("data.json") as file:  data = json.load(file)  
print(data)# Write JSON Data (Python Object -> JSON File)  
data = {  "name": "John",  "age": 30,  "city": "New York"  
}  
with open("data.json", mode="w") as file:  json.dump(data, file, indent=4)  

232. Improve the Password Manager Project

Password Manager Project

from tkinter import *
from tkinter import messagebox
from random import choice, randint, shuffle
import pyperclip
import jsondef generate_password():letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']numbers = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']symbols = ['!', '#', '$', '%', '&', '(', ')', '*', '+']password_letters = [choice(letters) for _ in range(randint(8, 10))]password_symbols = [choice(symbols) for _ in range(randint(2, 4))]password_numbers = [choice(numbers) for _ in range(randint(2, 4))]password_list = password_letters + password_symbols + password_numbersshuffle(password_list)password = "".join(password_list)password_entry.delete(0, END)password_entry.insert(0, password)pyperclip.copy(password)def save():website = website_entry.get()email = email_entry.get()password = password_entry.get()new_data = {website: {"email": email,"password": password,}}if len(website) == 0 or len(email) == 0 or len(password) == 0:messagebox.showinfo(title="Oops",message="Please make sure you haven't left any fields empty.")else:try:with open("data.json", "r") as data_file:data = json.load(data_file)except FileNotFoundError:with open("data.json", "w") as data_file:json.dump(new_data, data_file, indent=4)else:data.update(new_data)with open("data.json", "w") as data_file:json.dump(data, data_file, indent=4)finally:website_entry.delete(0, END)password_entry.delete(0, END)def find_password():website = website_entry.get()try:with open("data.json") as data_file:data = json.load(data_file)except FileNotFoundError:messagebox.showinfo(title="Error", message="No Data File Found.")else:if website in data:email = data[website]["email"]password = data[website]["password"]messagebox.showinfo(title=website, message=f"Email: {email}\nPassword: {password}")else:messagebox.showinfo(title="Error", message=f"No details for {website} exists.")# UI SETUP
window = Tk()
window.title("Password Manager")
window.config(padx=50, pady=50)canvas = Canvas(width=200, height=200)
logo_img = PhotoImage(file="logo.png")
canvas.create_image(100, 100, image=logo_img)
canvas.grid(column=0, row=0, columnspan=3)# Labels
website_label = Label(text="Website:")
website_label.grid(column=0, row=1)
email_label = Label(text="Email/Username:")
email_label.grid(column=0, row=2)
password_label = Label(text="Password:")
password_label.grid(column=0, row=3)# Entries
website_entry = Entry(width=20)
website_entry.grid(column=1, row=1)
website_entry.focus()
email_entry = Entry(width=38)
email_entry.grid(column=1, row=2, columnspan=2)
email_entry.insert(0, "[e-mail]")
password_entry = Entry(width=20)
password_entry.grid(column=1, row=3)# Buttons
search_button = Button(text="Search", width=16, command=find_password)
search_button.grid(row=1, column=2)
generate_button = Button(text="Generate Password", width=16, command=generate_password)
generate_button.grid(column=2, row=3)
add_button = Button(text="Add", width=38, command=save)
add_button.grid(column=1, row=4, columnspan=2)window.mainloop()