python - 如何在Android中保持kivy服务在后台运行(切换到其他应用程序或锁定屏幕时服务仍然运行)？

Question

我正在尝试用 kivy 构建一个 android APP，我的要求很简单:
打开安卓APP，从0开始计数，每隔5秒在状态栏弹出一个提示。提示内容为当前计数值。如果APP切换到后台或锁屏，状态栏仍会每5秒弹出一次提示。
这是我从网上修改的代码:

from os.path import join, dirname, realpath

import kivy
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from plyer import notification
from plyer.utils import platform
from kivy.properties import DictProperty
kivy.require('1.8.0')

a = 0
from kivy.utils import platform
if platform == 'android':
    #pass
    from jnius import autoclass
    package_name = 'net.saband.myapp'
    service_name = 'ENTRYPOINT_TO_PY'
    service = autoclass('{}.Service{}'.format(package_name, service_name))
    mActivity = autoclass('org.kivy.android.PythonActivity').mActivity
    service.start(mActivity, '')

class NotificationDemo(BoxLayout):
    kwargs = DictProperty()
    def update(self,dt):
        global a
        a = a + 1
        mode = 'fancy'
        message = str(a)
        title = self.ids.notification_title.text
        self.ids.notification_text.text = message
        ticker = self.ids.ticker_text.text
        self.kwargs = {'title': title, 'message': message, 'ticker': ticker}
        if mode == 'fancy':
            self.kwargs['app_name'] = "Plyer Notification Example"
            if platform == "win":
                self.kwargs['app_icon'] = join(dirname(realpath(__file__)),
                                          'plyer-icon.ico')
                self.kwargs['timeout'] = 4
            else:
                self.kwargs['app_icon'] = join(dirname(realpath(__file__)),
                                          'plyer-icon.png')
        elif mode == 'toast':
            self.kwargs['toast'] = True
        print(message)
        notification.notify(**self.kwargs)


class NotificationDemoApp(App):
    def build(self):
        notify = NotificationDemo()
        Clock.schedule_interval(notify.update, 5)
        return notify

    def on_pause(self):
        return True

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

并且kv文件没问题，在下面列出

#:kivy 1.8.0
<NotificationDemo>:
    orientation: 'vertical'
    Widget:
    BoxLayout:
        orientation: 'horizontal'
        size_hint: 1, None
        TextInput:
            id: notification_title
            text: 'Put title here'
            size_hint: 1, None
        TextInput:
            id: notification_text
            text: 'Put message here'
            size_hint: 1, None
        TextInput:
            id: ticker_text
            text: 'New notification'
            size_hint: 1, None
    Button:
        text: 'Toast Notification'
        size_hint: 1, None
        on_release: root.do_notify(mode='toast')
    Button:
        text: 'Simple Notification'
        size_hint: 1, None
        on_release: root.do_notify(mode='normal')
    Button:
        text: 'Fancy Notification'
        size_hint: 1, None
        on_release: root.do_notify(mode='fancy')
    Widget:

，buildozer.spec 如下:

[app]

# (str) Title of your application
title = SteeringRemind

# (str) Package name
package.name = net.saband.myapp

# (str) Package domain (needed for android/ios packaging)
package.domain = org.SteeringRemind

# (str) Source code where the main.py live
source.dir = .

# (list) Source files to include (let empty to include all the files)
source.include_exts = py,png,jpg,kv,atlas,ttf,wav

# (list) List of inclusions using pattern matching
source.include_patterns = assets/*,images/*.png

# (list) Source files to exclude (let empty to not exclude anything)
#source.exclude_exts = spec

# (list) List of directory to exclude (let empty to not exclude anything)
#source.exclude_dirs = tests, bin

# (list) List of exclusions using pattern matching
#source.exclude_patterns = license,images/*/*.jpg

# (str) Application versioning (method 1)
version = 0.100.0

# (str) Application versioning (method 2)
# version.regex = __version__ = ['"](.*)['"]
# version.filename = %(source.dir)s/main.py

# (list) Application requirements
# comma separated e.g. requirements = sqlite3,kivy
requirements = python3,kivy,pillow,plyer,pyjnius

# (str) Custom source folders for requirements
# Sets custom source for any requirements with recipes
# requirements.source.kivy = ../../kivy

# (list) Garden requirements
#garden_requirements =

# (str) Presplash of the application
#presplash.filename = %(source.dir)s/assets/background.jpg

android.presplash_color=#FFFFFF

# (str) Icon of the application
#icon.filename = %(source.dir)s/assets/steering.png

# (str) Supported orientation (one of landscape, sensorLandscape, portrait or all)
orientation = portrait

# (list) List of service to declare
services = NAME:ENTRYPOINT_TO_PY,NAME2:ENTRYPOINT2_TO_PY
#services = NAME:Myservice
#
# OSX Specific
#

#
# author = © Copyright Info

# change the major version of python used by the app
#osx.python_version = 3

# Kivy version to use
#osx.kivy_version = 1.9.1

#
# Android specific
#

# (bool) Indicate if the application should be fullscreen or not
fullscreen = 0

# (string) Presplash background color (for new android toolchain)
# Supported formats are: #RRGGBB #AARRGGBB or one of the following names:
# red, blue, green, black, white, gray, cyan, magenta, yellow, lightgray,
# darkgray, grey, lightgrey, darkgrey, aqua, fuchsia, lime, maroon, navy,
# olive, purple, silver, teal.
#android.presplash_color = #FFFFFF

# (list) Permissions
android.permissions = INTERNET

# (int) Target Android API, should be as high as possible.
android.api = 28

# (int) Minimum API your APK will support.
android.minapi = 21

# (int) Android SDK version to use
#android.sdk = 20

# (str) Android NDK version to use
android.ndk = 17c

# (int) Android NDK API to use. This is the minimum API your app will support, it should usually match android.minapi.
#android.ndk_api = 21

# (bool) Use --private data storage (True) or --dir public storage (False)
#android.private_storage = True

# (str) Android NDK directory (if empty, it will be automatically downloaded.)
android.ndk_path = /home/kivy/Android/android-ndk-r17c

# (str) Android SDK directory (if empty, it will be automatically downloaded.)
android.sdk_path = /home/kivy/Android/android-sdk-28

# (str) ANT directory (if empty, it will be automatically downloaded.)
android.ant_path = /home/kivy/.buildozer/android/platform/apache-ant-1.9.4

# (bool) If True, then skip trying to update the Android sdk
# This can be useful to avoid excess Internet downloads or save time
# when an update is due and you just want to test/build your package
# android.skip_update = False

# (bool) If True, then automatically accept SDK license
# agreements. This is intended for automation only. If set to False,
# the default, you will be shown the license when first running
# buildozer.
# android.accept_sdk_license = False

# (str) Android entry point, default is ok for Kivy-based app
#android.entrypoint = org.renpy.android.PythonActivity

# (list) Pattern to whitelist for the whole project
#android.whitelist =

# (str) Path to a custom whitelist file
#android.whitelist_src =

# (str) Path to a custom blacklist file
#android.blacklist_src =

# (list) List of Java .jar files to add to the libs so that pyjnius can access
# their classes. Don't add jars that you do not need, since extra jars can slow
# down the build process. Allows wildcards matching, for example:
# OUYA-ODK/libs/*.jar
#android.add_jars = foo.jar,bar.jar,path/to/more/*.jar

# (list) List of Java files to add to the android project (can be java or a
# directory containing the files)
#android.add_src =

# (list) Android AAR archives to add (currently works only with sdl2_gradle
# bootstrap)
#android.add_aars =

# (list) Gradle dependencies to add (currently works only with sdl2_gradle
# bootstrap)
#android.gradle_dependencies =

# (list) Java classes to add as activities to the manifest.
#android.add_activites = com.example.ExampleActivity

# (str) OUYA Console category. Should be one of GAME or APP
# If you leave this blank, OUYA support will not be enabled
#android.ouya.category = GAME

# (str) Filename of OUYA Console icon. It must be a 732x412 png image.
#android.ouya.icon.filename = %(source.dir)s/data/ouya_icon.png

# (str) XML file to include as an intent filters in <activity> tag
#android.manifest.intent_filters =

# (str) launchMode to set for the main activity
#android.manifest.launch_mode = standard

# (list) Android additional libraries to copy into libs/armeabi
#android.add_libs_armeabi = libs/android/*.so
#android.add_libs_armeabi_v7a = libs/android-v7/*.so
#android.add_libs_arm64_v8a = libs/android-v8/*.so
#android.add_libs_x86 = libs/android-x86/*.so
#android.add_libs_mips = libs/android-mips/*.so

# (bool) Indicate whether the screen should stay on
# Don't forget to add the WAKE_LOCK permission if you set this to True
#android.wakelock = False

# (list) Android application meta-data to set (key=value format)
#android.meta_data =

# (list) Android library project to add (will be added in the
# project.properties automatically.)
#android.library_references =

# (list) Android shared libraries which will be added to AndroidManifest.xml using <uses-library> tag
#android.uses_library =

# (str) Android logcat filters to use
#android.logcat_filters = *:S python:D

# (bool) Copy library instead of making a libpymodules.so
#android.copy_libs = 1

# (str) The Android arch to build for, choices: armeabi-v7a, arm64-v8a, x86, x86_64
android.arch = armeabi-v7a

#
# Python for android (p4a) specific
#

# (str) python-for-android fork to use, defaults to upstream (kivy)
#p4a.fork = kivy

# (str) python-for-android branch to use, defaults to master
#p4a.branch = master

# (str) python-for-android git clone directory (if empty, it will be automatically cloned from github)
p4a.source_dir = ~/Repos/python-for-android/
# (str) The directory in which python-for-android should look for your own build recipes (if any)
#p4a.local_recipes =

# (str) Filename to the hook for p4a
#p4a.hook =

# (str) Bootstrap to use for android builds
# p4a.bootstrap = sdl2

# (int) port number to specify an explicit --port= p4a argument (eg for bootstrap flask)
#p4a.port =


#
# iOS specific
#

# (str) Path to a custom kivy-ios folder
#ios.kivy_ios_dir = ../kivy-ios
# Alternately, specify the URL and branch of a git checkout:
#ios.kivy_ios_url = https://github.com/kivy/kivy-ios
#ios.kivy_ios_branch = master

# Another platform dependency: ios-deploy
# Uncomment to use a custom checkout
#ios.ios_deploy_dir = ../ios_deploy
# Or specify URL and branch
#ios.ios_deploy_url = https://github.com/phonegap/ios-deploy
#ios.ios_deploy_branch = 1.7.0

# (str) Name of the certificate to use for signing the debug version
# Get a list of available identities: buildozer ios list_identities
#ios.codesign.debug = "iPhone Developer: <lastname> <firstname> (<hexstring>)"

# (str) Name of the certificate to use for signing the release version
#ios.codesign.release = %(ios.codesign.debug)s


[buildozer]

# (int) Log level (0 = error only, 1 = info, 2 = debug (with command output))
log_level = 2

# (int) Display warning if buildozer is run as root (0 = False, 1 = True)
warn_on_root = 0

# (str) Path to build artifact storage, absolute or relative to spec file
# build_dir = ./.buildozer

# (str) Path to build output (i.e. .apk, .ipa) storage
# bin_dir = ./bin

#    -----------------------------------------------------------------------------
#    List as sections
#
#    You can define all the "list" as [section:key].
#    Each line will be considered as a option to the list.
#    Let's take [app] / source.exclude_patterns.
#    Instead of doing:
#
#[app]
#source.exclude_patterns = license,data/audio/*.wav,data/images/original/*
#
#    This can be translated into:
#
#[app:source.exclude_patterns]
#license
#data/audio/*.wav
#data/images/original/*
#


#    -----------------------------------------------------------------------------
#    Profiles
#
#    You can extend section / key with a profile
#    For example, you want to deploy a demo version of your application without
#    HD content. You could first change the title to add "(demo)" in the name
#    and extend the excluded directories to remove the HD content.
#
#[app@demo]
#title = My Application (demo)
#
#[app:source.exclude_patterns@demo]
#images/hd/*
#
#    Then, invoke the command line with the "demo" profile:
#
#buildozer --profile demo android debug

当我使用“buildozer android debug”时，apk 生成正确，但有警告

[INFO]:    # APK renamed to net.saband.myapp-0.100.0-debug.apk
[DEBUG]:   -> running cp /home/kivy/Repos/Python3/kivy/examples/demo/test/.buildozer/android/platform/build/dists/net.saband.myapp/build/outputs/apk/debug/net.saband.myapp-debug.apk net.saband.myapp-0.100.0-debug.apk
WARNING: Received a --sdk argument, but this argument is deprecated and does nothing.
No compiled python is present to zip, skipping.
No setup.py/pyproject.toml used, copying full private data into .apk.
Applying Java source code patches...
Applying patch: src/patches/SDLActivity.java.patch
Warning: failed to apply patch (exit code 1), assuming it is already applied: src/patches/SDLActivity.java.patch

当我在安卓手机上安装apk时，在预启动显示后它会立即崩溃，
如果我像下面这样注释掉关于jnius的行，apk可以正常运行，但服务不会在后台运行(状态栏不弹出提示)

if platform == 'android':
    #pass
    from jnius import autoclass
    package_name = 'net.saband.myapp'
    service_name = 'ENTRYPOINT_TO_PY'
    #service = autoclass('{}.Service{}'.format(package_name, service_name))
    #mActivity = autoclass('org.kivy.android.PythonActivity').mActivity
    #service.start(mActivity, '')

不知道是我对jnius的理解有误，还是配置错误
再次......任何帮助将不胜感激!

Answer 1

经过几天的测试，我解决了这个问题
我之前对后台操作的理解确实有问题，
或者我的解决方案只是实现目标的方法之一。
在 main.py ，定义服务并启动它:

from jnius import autoclass
SERVICE_NAME = u'{packagename}.Service{servicename}'.format(
    packagename=u'org.kivy.test',
    servicename=u'Myservice'
)
service = autoclass(SERVICE_NAME)
mActivity = autoclass(u'org.kivy.android.PythonActivity').mActivity
argument = ''
service.start(mActivity, argument)

在 buildozer.spec :

# (str) Package name
package.name = test

# (str) Package domain (needed for android/ios packaging)
package.domain = org.kivy

# (list) List of service to declare
services = Myservice:service.py

然后，编辑 service.py如所须。 main.py和 service.py可以使用 oscpy 进行通信.
通过以上操作，可以在打开APP后弹出通知，甚至将APP切换到后台。