python kivy on android 关闭应用程序后如何使服务继续工作

Question

我希望我的服务在关闭应用程序后继续工作，但我做不到。我听说我应该使用 startForeground() 但如何在 python 中使用？应用代码：

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from jnius import autoclass
from kivy.uix.label import Label
class MyApp(App):
    def build(self):
        fl = FloatLayout()
        try:
            service = autoclass('org.test.myapp.ServiceMyservice')
            mActivity = autoclass('org.kivy.android.PythonActivity').mActivity                                                                        
            service.start(mActivity, "")
        except Exception as error:
            fl.add_widget(Label(text=str(error), font_size=(40)))
        return fl
if __name__ == '__main__':
    MyApp().run()

我的代码 service/main.py:

import pickle, socket, jnius

for x in range(5):
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    host = 'example-78945.portmap.host'
    port = 78945
    s.connect((host,port))
    s.send(('hello world').encode('utf-8'))

ServiceMyservice.java代码：

package org.test.myapp.ServiceMyservice;

import android.content.Intent;
import android.content.Context;
import org.kivy.android.PythonService;
import android.app.Notification;
import android.app.Service;

public class ServiceMyservice extends PythonService {
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
    }
    protected int getServiceId() {
        return 1;
    }

    static public void start(Context ctx, String pythonServiceArgument) {
        Intent intent = new Intent(ctx, ServiceMyservice.class);
        String argument = ctx.getFilesDir().getAbsolutePath() + "/app";
        intent.putExtra("androidPrivate", ctx.getFilesDir().getAbsolutePath());
        intent.putExtra("androidArgument", argument);
        intent.putExtra("serviceTitle", "My Application");
        intent.putExtra("serviceDescription", "Myservice");                                                                     
        intent.putExtra("serviceEntrypoint", "./service/main.py");
        intent.putExtra("pythonName", "myservice");
        intent.putExtra("serviceStartAsForeground", true);
        intent.putExtra("pythonHome", argument);
        intent.putExtra("pythonPath", argument + ":" + argument + "/lib");
        intent.putExtra("pythonServiceArgument", pythonServiceArgument);
        ctx.startService(intent);
    }

    static public void stop(Context ctx) {
        Intent intent = new Intent(ctx, ServiceMyservice.class);
        ctx.stopService(intent);
    }
}

服务启动并运行，但在关闭应用程序后，服务也会关闭。如何修复？？？？

Answer 1

This workaround is basically making the service got an auto restart. That means your service will start from beginning. And yes, this is hardcoding.

向服务模板文件中的 start() 方法添加一个字符串参数

我的是重启参数。这将是额外的 activity 意图传递给由 ctx.startService() 方法触发的 onStartCommand() 方法。然后将 'autoRestartService' 与 restart 参数值一起放置。

我的 .buildozer/android/platform/build-<您的架构>/dists/<您的应用程序>/templates/Service.tmpl.java:

package {{ args.package }};

import android.content.Intent;
import android.content.Context;
import org.kivy.android.PythonService;


public class Service{{ name|capitalize }} extends PythonService {

    {% if sticky %}
    @Override
    public int startType() {
        return START_STICKY;
    }
    {% endif %}

    @Override
    protected int getServiceId() {
        return {{ service_id }};
    }
                                  /*add 'restart' String argument to the start() method*/
    static public void start(Context ctx, String pythonServiceArgument, String restart) {
        Intent intent = new Intent(ctx, Service{{ name|capitalize }}.class);
        String argument = ctx.getFilesDir().getAbsolutePath() + "/app";
        intent.putExtra("androidPrivate", ctx.getFilesDir().getAbsolutePath());
        intent.putExtra("androidArgument", argument);
        intent.putExtra("serviceTitle", "{{ args.name }}");
        intent.putExtra("serviceDescription", "{{ name|capitalize }}");
        intent.putExtra("serviceEntrypoint", "{{ entrypoint }}");
        intent.putExtra("pythonName", "{{ name }}");
        intent.putExtra("serviceStartAsForeground", "{{ foreground|lower }}");
        intent.putExtra("pythonHome", argument);
        intent.putExtra("pythonPath", argument + ":" + argument + "/lib");
        intent.putExtra("pythonServiceArgument", pythonServiceArgument);
        intent.putExtra("autoRestartService", restart); /*<-- add this line*/
        ctx.startService(intent);
    }

    static public void stop(Context ctx) {
        Intent intent = new Intent(ctx, Service{{ name|capitalize }}.class);
        ctx.stopService(intent);
    }
}

在 PythonService 的 onStartCommand()

中设置 autoRestartService 值

看看下面 PythonService 的 onDestroy() 方法。如果服务被终止（由关闭应用程序或从最近的应用程序滑动引起），将触发 onDestroy() 方法。有一个选项是否重启服务取决于 autoRestartService 值。因此，通过从 intent extras 获取它，在 onStartCommand() 方法中设置它。

我的 .buildozer/android/platform/build-<您的架构>/dists/<您的应用程序>/src/main/org/kivy/android/PythonService.java:

package org.kivy.android;

import android.os.Build;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import android.app.Service;
import android.os.IBinder;
import android.os.Bundle;
import android.content.Intent;
import android.content.Context;
import android.util.Log;
import android.app.Notification;
import android.app.PendingIntent;
import android.os.Process;
import java.io.File;

//imports for channel definition
import android.app.NotificationManager;
import android.app.NotificationChannel;
import android.graphics.Color;

public class PythonService extends Service implements Runnable {

    // Thread for Python code
    private Thread pythonThread = null;

    // Python environment variables
    private String androidPrivate;
    private String androidArgument;
    private String pythonName;
    private String pythonHome;
    private String pythonPath;
    private String serviceEntrypoint;
    // Argument to pass to Python code,
    private String pythonServiceArgument;


    public static PythonService mService = null;
    private Intent startIntent = null;

    private boolean autoRestartService = false;

    public void setAutoRestartService(boolean restart) {
        autoRestartService = restart;
    }

    public int startType() {
        return START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (pythonThread != null) {
            Log.v("python service", "service exists, do not start again");
            return START_NOT_STICKY;
        }

        startIntent = intent;
        Bundle extras = intent.getExtras();
        androidPrivate = extras.getString("androidPrivate");
        androidArgument = extras.getString("androidArgument");
        serviceEntrypoint = extras.getString("serviceEntrypoint");
        pythonName = extras.getString("pythonName");
        pythonHome = extras.getString("pythonHome");
        pythonPath = extras.getString("pythonPath");
        boolean serviceStartAsForeground = (
            extras.getString("serviceStartAsForeground").equals("true")
        );
        pythonServiceArgument = extras.getString("pythonServiceArgument");
        autoRestartService = (
            extras.getString("autoRestartService").equals("true") //this will return boolean for autoRestartservice
        );
        pythonThread = new Thread(this);
        pythonThread.start();

        if (serviceStartAsForeground) {
            doStartForeground(extras);
        }

        return startType();
    }

    protected int getServiceId() {
        return 1;
    }

    protected void doStartForeground(Bundle extras) {
        String serviceTitle = extras.getString("serviceTitle");
        String serviceDescription = extras.getString("serviceDescription");
        Notification notification;
        Context context = getApplicationContext();
        Intent contextIntent = new Intent(context, PythonActivity.class);
        PendingIntent pIntent = PendingIntent.getActivity(context, 0, contextIntent,
            PendingIntent.FLAG_UPDATE_CURRENT);

        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
            notification = new Notification(
                context.getApplicationInfo().icon, serviceTitle, System.currentTimeMillis());
            try {
                // prevent using NotificationCompat, this saves 100kb on apk
                Method func = notification.getClass().getMethod(
                    "setLatestEventInfo", Context.class, CharSequence.class,
                    CharSequence.class, PendingIntent.class);
                func.invoke(notification, context, serviceTitle, serviceDescription, pIntent);
            } catch (NoSuchMethodException | IllegalAccessException |
                     IllegalArgumentException | InvocationTargetException e) {
            }
        } else {
            // for android 8+ we need to create our own channel
            // 
            String NOTIFICATION_CHANNEL_ID = "org.kivy.p4a";    //TODO: make this configurable
            String channelName = "Background Service";                //TODO: make this configurable
            NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, 
                NotificationManager.IMPORTANCE_NONE);
            
            chan.setLightColor(Color.BLUE);
            chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
            NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
            manager.createNotificationChannel(chan);

            Notification.Builder builder = new Notification.Builder(context, NOTIFICATION_CHANNEL_ID);
            builder.setContentTitle(serviceTitle);
            builder.setContentText(serviceDescription);
            builder.setContentIntent(pIntent);
            builder.setSmallIcon(context.getApplicationInfo().icon);
            notification = builder.build();
        }
        startForeground(getServiceId(), notification);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        pythonThread = null;
        if (autoRestartService && startIntent != null) {
            Log.v("python service", "service restart requested");
            startService(startIntent);
        }
        Process.killProcess(Process.myPid());
    }

    /**
     * Stops the task gracefully when killed.
     * Calling stopSelf() will trigger a onDestroy() call from the system.
     */
    @Override
    public void onTaskRemoved(Intent rootIntent) {
        super.onTaskRemoved(rootIntent);
        stopSelf();
    }

    @Override
    public void run(){
        String app_root =  getFilesDir().getAbsolutePath() + "/app";
        File app_root_file = new File(app_root);
        PythonUtil.loadLibraries(app_root_file,
            new File(getApplicationInfo().nativeLibraryDir));
        this.mService = this;
        nativeStart(
            androidPrivate, androidArgument,
            serviceEntrypoint, pythonName,
            pythonHome, pythonPath,
            pythonServiceArgument);
        stopSelf();
    }

    // Native part
    public static native void nativeStart(
            String androidPrivate, String androidArgument,
            String serviceEntrypoint, String pythonName,
            String pythonHome, String pythonPath,
            String pythonServiceArgument);
}

那里有 setAutoRestartService() 方法，但我们不能调用它，因为它是 non-static 方法。

最后一件事，buildozer.spec

为 buildozer.spec 添加 FOREGROUND_SERVICE 权限和服务。

android.permissions = FOREGROUND_SERVICE
...

services = myservice:./path/to/your-service.py:foreground

现在通过将 'true' 字符串作为第三个位置参数来启动服务。

activity = autoclass('org.kivy.android.PythonActivity').mActivity
service = autoclass('com.omdo.example.ServiceMyservice')
service.start(activity, '', 'true')

注：我不是很懂Java，也许谁能把它说得简单点。

Reference:

Static vs. Non-Static

Foreground vs. Background

Intents & Extras

Create python-for-android Service

Answer 2

@omdo: 谢谢你的回答。

你添加权限的方法对我有用。虽然我知道解决方案是添加 FOREGROUND_SERVICE 的权限，我尝试添加：

from android.permissions import request_permissions, Permission

request_permissions([Permission.FOREGROUND_SERVICE])

但没有用，直到我根据您的建议修改了 buildozer.spec。

python kivy on android 关闭应用程序后如何使服务继续工作

how to make the service continue working after closing the app in python kivy on android

java

python

android

service

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