Android如果不存在python，如何创建一个新的json文件

Question

I am creating an app that lets the user enter information and can save the data into a json file called hello.json. This works fine when the file exists, however when testing it on an android it crashed because it does not contain this file. How can I create a new json file on android if it doesn't exist?

.py file

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.popup import Popup
from kivy.uix.button import Button
from kivy.graphics import Color, Rectangle
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.image import AsyncImage
from kivy.uix.label import Label
from kivy.properties import StringProperty, ListProperty
from kivy.uix.behaviors import ButtonBehavior
from kivy.uix.textinput import TextInput
from kivy.network.urlrequest import UrlRequest
from kivy.storage.jsonstore import JsonStore
from os.path import exists
from kivy.compat import iteritems
from kivy.storage import AbstractStore
from json import loads, dump
from kivy.config import Config



class Phone(FloatLayout):
    def __init__(self, **kwargs):
        # make sure we aren't overriding any important functionality
        super(Phone, self).__init__(**kwargs)

    with self.canvas.before:
        Color(0, 1, 0, 1)  # green; colors range from 0-1 instead of 0-255
        self.rect = Rectangle(size=self.size, pos=self.pos)

    self.bind(size=self._update_rect, pos=self._update_rect)

    with open('hello.json') as inFile:
        try:
            data = Phone.load(self)
        except KeyError:
            data = []

def _update_rect(self, instance, value):
    self.rect.pos = instance.pos
    self.rect.size = instance.size

def product(self, instance):
    self.result.text = str(float(self.w.text) * 703/ (float(self.h.text) * float(self.h.text)))

def save(self):
    store = JsonStore('hello.json')
    name = self.n.text
    gender = self.g.text
    dtype = self.t.text
    height = self.h.text
    weight = self.w.text
    bmi = self.result.text
    medications = self.m.text
    insulin = self.ti.text
    store.put('profile', name=name, gender=gender, dtype=dtype, height=height, weight=weight, bmi=bmi, medications=medications, insulin=insulin)



def load(self):
    store = JsonStore('hello.json')
    profile = store.get('profile')
    self.n.text = profile['name']
    self.g.text = profile['gender']
    self.t.text = profile['dtype']
    self.h.text = profile['height']
    self.w.text = profile['weight']
    self.result.text = profile['bmi']
    self.m.text = profile['medications']
    self.ti.text = profile['insulin']

    try:
        store.get('profile')['name']
    except KeyError:
        name = ""
    else:
        name = store.get('profile')['name']        




presentation = Builder.load_file("main.kv")

class PhoneApp(App):
    def build(self):
        store = JsonStore('hello.json')

        return Phone()



if __name__ == '__main__':
    PhoneApp().run()

Answer 1

You should use with open('hello.json', 'a+') as inFile

a+ Opens a file for both appending and reading. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.