前台服务永远不会停止 xamarin android

Question

我有从剪贴板读取并写入的 xamarin android 应用程序。 如果用户点击按钮，它使用前台服务。 问题是当用户再次点击按钮时，服务从正在运行的服务中消失，但仍然在做它的工作（编辑复制的文本）。 我怎样才能完全阻止它工作？

前景.cs：

        public override IBinder OnBind(Intent intent)
        {
            return null;
        }
    public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
    {
        Clipboard.ClipboardContentChanged += async (o, e) =>
            {
                var text = await Clipboard.GetTextAsync();
                Toast.MakeText(this, text, ToastLength.Long).Show();
                if (text.Contains("@"))
                {
                    await Clipboard.SetTextAsync(text.Replace("@", ""));
                }
            };
        Notification notif = ReturnNotif();
        StartForeground(1, notif);
        return StartCommandResult.NotSticky;
    }

        public override void OnDestroy()
        {
            base.OnDestroy();
        }

        public override void OnCreate()
        {
            base.OnCreate();
        }
        public override bool StopService(Intent name)
        {
            StopForeground(true);
            StopSelf();
            return base.StopService(name);
        }

主活动.cs：

    if (id == Resource.Id.myService)
    {
        if (count != 1)
        {
            count = 1;
            var intent = new Intent(this, typeof(foreground));
            intent.SetAction("No");
            if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
            {
                StartForegroundService(intent);
            }
            else
            {
                StartService(intent);
            }
        }
        else
        {
            var intent = new Intent(this,typeof(foreground));
            StopService(intent);
            Toast.MakeText(this, "Service Stopped", ToastLength.Long).Show();
            count = 0;
        }
    }

我做错了什么？

编辑：如果从最近使用的应用程序中删除该应用程序，服务将完全停止。

Answer 1

在您的MyForegroundService.cs 。 只需在OnDestroy()方法中添加StopForeground(true) ，如以下代码。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace ForegroundServiceDemo
{
    [Service]
    class MyForegroundService : Service
    {
        public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;

        [return: GeneratedEnum]
        public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
        {
            CreateNotificationChannel();
            string messageBody = "service starting";
           // / Create an Intent for the activity you want to start
           Intent resultIntent = new Intent(this,typeof(Activity1));
           // Create the TaskStackBuilder and add the intent, which inflates the back stack
           TaskStackBuilder stackBuilder = TaskStackBuilder.Create(this);
           stackBuilder.AddNextIntentWithParentStack(resultIntent);
           // Get the PendingIntent containing the entire back stack
           PendingIntent resultPendingIntent = stackBuilder.GetPendingIntent(0, PendingIntentFlags.UpdateCurrent);
           var notification = new Notification.Builder(this, "10111")
            .SetContentIntent(resultPendingIntent)
            .SetContentTitle("Foreground")
            .SetContentText(messageBody)
            .SetSmallIcon(Resource.Drawable.main)
            .SetOngoing(true)
            .Build();
            StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
             //do you work
            return StartCommandResult.Sticky;

           
        }
        public override void OnDestroy()
        {
            base.OnDestroy();
            StopForeground(true);
        }
        public override IBinder OnBind(Intent intent)
        {
            return null;
        }

        void CreateNotificationChannel()
        {
            if (Build.VERSION.SdkInt < BuildVersionCodes.O)
            {
                
                return;
            }

            var channelName = Resources.GetString(Resource.String.channel_name);
            var channelDescription = GetString(Resource.String.channel_description);
            var channel = new NotificationChannel("10111", channelName, NotificationImportance.Default)
            {
                Description = channelDescription
            };

            var notificationManager = (NotificationManager)GetSystemService(NotificationService);
            notificationManager.CreateNotificationChannel(channel);
        }

    }
}

当你想阻止它时。 只需调用以下代码。

   Android.App.Application.Context.StopService(intent);

这是我在活动中的代码。

public class MainActivity : AppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.activity_main);
            Button button1 = FindViewById<Button>(Resource.Id.button1);
            Button button2 = FindViewById<Button>(Resource.Id.button2);
            button2.Click += Button2_Click;
            button1.Click += Button1_Click;
        }
        Intent intent;
        private void Button2_Click(object sender, System.EventArgs e)
        {
            // stop foreground service.
            Android.App.Application.Context.StopService(intent);
        }

        private void Button1_Click(object sender, System.EventArgs e)
        {
             intent = new Intent(Android.App.Application.Context, typeof(MyForegroundService));

  // start foreground service.
            if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
            {
                StartForegroundService(intent);
              
            }
        }

这里正在运行 GIF。

====更新====

预期行为是：当服务停止时，用户可以正常复制和粘贴而不受服务干扰

您可以使用以下方式来实现。使用Clipboard.ClipboardContentChanged += Clipboard_ClipboardContentChanged; 要执行该行为，请使用Clipboard.ClipboardContentChanged -= Clipboard_ClipboardContentChanged; 禁用OnDistory方法中的行为。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Xamarin.Essentials;

namespace ForegroundServiceDemo
{
    [Service]
    class MyForegroundService : Service
    {
        public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;

        [return: GeneratedEnum]
        public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
        {
            CreateNotificationChannel();
            string messageBody = "service starting";


            Clipboard.ClipboardContentChanged += Clipboard_ClipboardContentChanged;

             // / Create an Intent for the activity you want to start
             Intent resultIntent = new Intent(this,typeof(Activity1));
           // Create the TaskStackBuilder and add the intent, which inflates the back stack
           TaskStackBuilder stackBuilder = TaskStackBuilder.Create(this);
           stackBuilder.AddNextIntentWithParentStack(resultIntent);
           // Get the PendingIntent containing the entire back stack
           PendingIntent resultPendingIntent = stackBuilder.GetPendingIntent(0, PendingIntentFlags.UpdateCurrent);
           var notification = new Notification.Builder(this, "10111")
            .SetContentIntent(resultPendingIntent)
            .SetContentTitle("Foreground")
            .SetContentText(messageBody)
            .SetSmallIcon(Resource.Drawable.main)
            .SetOngoing(true)
            .Build();
            StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
             //do you work
            return StartCommandResult.Sticky;

           
        }

        private async void Clipboard_ClipboardContentChanged(object sender, EventArgs e)
        {
            //throw new NotImplementedException();

            var text = await Clipboard.GetTextAsync();
            Toast.MakeText(this, text, ToastLength.Long).Show();
            if (text.Contains("@"))
            {
                await Clipboard.SetTextAsync(text.Replace("@", ""));
            }
        }

        public override void OnDestroy()
        {
            base.OnDestroy();
            Clipboard.ClipboardContentChanged -= Clipboard_ClipboardContentChanged;

            StopForeground(true);
        }
        public override IBinder OnBind(Intent intent)
        {
            return null;
        }

        void CreateNotificationChannel()
        {
            if (Build.VERSION.SdkInt < BuildVersionCodes.O)
            {
                
                return;
            }

            var channelName = Resources.GetString(Resource.String.channel_name);
            var channelDescription = GetString(Resource.String.channel_description);
            var channel = new NotificationChannel("10111", channelName, NotificationImportance.Default)
            {
                Description = channelDescription
            };

            var notificationManager = (NotificationManager)GetSystemService(NotificationService);
            notificationManager.CreateNotificationChannel(channel);
        }

    }
}

这是运行GIF。

Answer 2

为防止出现此问题，请在启动前台方法时在 Properties 字典中添加一个“myServiceIsRunning”布尔值，如下所示：

Application.Current.Properties["myServiceIsRunning"] = true

使用get函数或者任何你想要的，在启动前台方法之前，验证密钥“myServiceIsRunning”是否存在，如果存在，他的状态如何：

public bool getRunningStateMyService(){
    bool myServiceIsRunningValue;
    if (Application.Current.Properties.ContainsKey("myServiceIsRunning"))
    {
        myServiceIsRunningValue = Convert.ToBoolean(Application.Current.Properties["myServiceIsRunning"]);
    }
    else
    {
        myServiceIsRunningValue = false;
    }
    return locationServiceIsRunning;
}

获得值后，通过一个简单的 if{}/else{}，您可以选择是否启动新实例，无论您的服务是否正在运行。 或者，在您的情况下，只是阻止前台方法继续运行。

当您销毁前台方法时，不要忘记将您的值设置为 false。

属性字典可以存储关闭应用程序的数据。 您可以在此处获得更多信息： https : //docs.microsoft.com/fr-fr/xamarin/xamarin-forms/app-fundamentals/application-class#Properties_Dictionary