# -*- coding: utf-8 -*-
import shelve
from datetime import datetime
from flask import Flask, render_template, redirect, request, escape, Markup

app = Flask(__name__)

DATA_FILE = 'message'

def save_data(name, comment, create_at):
    """保存提交的数据"""
    database = shelve.open(DATA_FILE)
    if 'message_list' not in database:
        message_list = []
    else:
        message_list = database['message_list']

    message_list.insert(0, {
        'name': name,
        'comment': comment,
        'create_at': create_at,
    })
    database['message_list'] = message_list
    database.close()

def load_data():
    """返回已提交的数据"""
    database = shelve.open(DATA_FILE)
    message_list = database.get('message_list', [])
    database.close()
    return message_list

def post():
    """用于提交评论的URL"""
    name = request.form.get('name')
    comment = request.form.get('comment')
    create_at = datetime.now()

    save_data(name, comment, create_at)
    return redirect('/')

@app.route('/')
def index():
    message_list = load_data()
    return render_template('index.html', message_list=message_list)

@app.template_filter('nl2br')
def nl2br_filter(s):
    return escape(s).replace("\n", Markup('<br>'))

@app.template_filter('datetime_fmt')
def datetime_fmt_filter(dt):
    return dt.strftime('%Y-%m-%d %H:%M：%S')

if __name__ == '__main__':
    app.run('127.0.0.1', 8001, debug=True)

{% for message in message_list %}
        <h3>{{ message.name }} 的消息 ({{ message.create_at | datetime_fmt }}):</h3>
        <p>
            {{ message.comment | nl2br }}<p>
        </p>
{% endfor %}

Error message when running the program:

UnicodeDecodeError

UnicodeDecodeError: 'ascii' codec can't decode byte 0xef in position 16: ordinal not in range(128)

There is an error in the Chinese line, how to deal with it