如何在flask上设置dispatcher中间件中的login_required？

from flask import Flask, request
from werkzeug.wrappers import Response
from werkzeug.exceptions import Unauthorized

app = Flask(__name__)

def login_required(func):
    def wrapper(*args, **kwargs):
        # 检查用户是否已登录
        if not is_user_logged_in():
            raise Unauthorized()
        return func(*args, **kwargs)
    return wrapper

@app.route('/protected')
@login_required
def protected_route():
    return 'This is a protected route.'

class DispatcherMiddleware:
    def __init__(self, app, mounts):
        self.app = app
        self.mounts = mounts

    def __call__(self, environ, start_response):
        path_info = environ.get('PATH_INFO', '')
        for prefix, app in self.mounts:
            if path_info.startswith(prefix):
                environ['SCRIPT_NAME'] = prefix
                return app(environ, start_response)
        return self.app(environ, start_response)

protected_app = DispatcherMiddleware(app, [('/protected', app)])

if __name__ == '__main__':
    from werkzeug.serving import run_simple
    run_simple('localhost', 5000, protected_app)