为什么没有出现通知？

Question

我制作了一个应用程序来测试显示前台服务，然后尝试在真实应用程序中实现它以在一定时间后关闭 wifi，代码与我的测试应用程序相同，但它不显示通知。该服务工作正常但没有通知

主要Activity

package com.example.countdownclosewifi.UI;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Build;
import android.os.Bundle;
import android.widget.Toast;

import com.example.countdownclosewifi.MyService;
import com.example.countdownclosewifi.R;
import com.example.countdownclosewifi.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {
    private ActivityMainBinding binding;
    private BroadcastReceiver receiver;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

        // Intent filter to set the same action of the broadcast sender
        IntentFilter intentFilter_getRemainingTime = new IntentFilter();
        intentFilter_getRemainingTime.addAction("Count");

        // what will happen when the app receive a broadcast
        receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                int i = intent.getIntExtra("Show", 0);
                binding.timeLeft.setText(String.valueOf(i));
            }
        };
        registerReceiver(receiver, intentFilter_getRemainingTime);


        binding.start.setOnClickListener(view -> {
            if (binding.setTime.getText().toString().isEmpty() || Long.parseLong(binding.setTime.getText().toString()) == 0) {
                Toast.makeText(MainActivity.this, "Enter the duration", Toast.LENGTH_SHORT).show();
            } else {
                Intent serviceIntent = new Intent(this, MyService.class);
                int time = Integer.parseInt(binding.setTime.getText().toString());
                serviceIntent.putExtra("Time", time);
                if(Build.VERSION.SDK_INT>= Build.VERSION_CODES.O){
                    startForegroundService(serviceIntent);

                }
                else {
                    startService(serviceIntent);
                }

            }

        });

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(receiver);
    }
}

服务class

package com.example.countdownclosewifi;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
//import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.WifiManager;
import android.os.Build;
import android.os.IBinder;

import androidx.annotation.Nullable;
import androidx.core.app.NotificationCompat;

import com.example.countdownclosewifi.UI.MainActivity;

import java.util.Timer;
import java.util.TimerTask;

public class MyService extends Service {
    private WifiManager wifiManager;
    private int timeRemaining;
    private Timer timer;
    //    Intent intent;

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

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);

        IntentFilter intentFilter_stop = new IntentFilter();
        intentFilter_stop.addAction("Stop timer");


        timeRemaining = intent.getIntExtra("Time", 0);
        timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {

                if (timeRemaining == 0) {
                    wifiManager.setWifiEnabled(false);
                    timer.cancel();
                    stopSelf();
                }

                setNotification(timeRemaining);

                Intent intent = new Intent();
                intent.setAction("Count");
                intent.putExtra("Show", timeRemaining);
                sendBroadcast(intent);

                timeRemaining -= 1;


            }
        }, 0, 1000);

        return START_STICKY;
    }

    public void setNotification(int timeRemaining) {
        Intent notificationIntent = new Intent(this, MainActivity.class);
        PendingIntent pendingIntent =
                PendingIntent.getActivity(this, 0, notificationIntent, 0);

        String channel_id = "id";
        Notification notification;
        if (Build.VERSION.SDK_INT>= Build.VERSION_CODES.O) {
            notification = new Notification.Builder(this, channel_id)
                    .setContentTitle("You are running out of time")
                    .setContentText(String.valueOf(timeRemaining))
                    .setSmallIcon(R.drawable.wifi_24)
                    .setContentIntent(pendingIntent)
                    .setOnlyAlertOnce(true)
                    .build();
        } else {
            notification = new NotificationCompat.Builder(this, channel_id)
                    .setContentTitle("You are running out of time")
                    .setContentText(String.valueOf(timeRemaining))
                    .setSmallIcon(R.drawable.wifi_24)
                    .setContentIntent(pendingIntent)
                    .setOnlyAlertOnce(true)
                    .build();
        }

        // Notification ID cannot be 0.
        startForeground(1, notification);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            String id = "Notification Channel";
            CharSequence name = "notification";
            NotificationChannel notificationChannel = new NotificationChannel(id, name, NotificationManager.IMPORTANCE_DEFAULT);
            NotificationManager notificationManager = getSystemService(NotificationManager.class);
            notificationManager.createNotificationChannel(notificationChannel);
        }



    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        stopForeground(true);
    }
}

清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.countdownclosewifi">

    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.CountDownCloseWIFI">
        <activity android:name=".UI.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service android:name=".MyService"/>
    </application>

</manifest>

非常清楚，但我看不到显示此通知所缺少的内容。

Answer 1

使用 countdowntimer class 而不是 timerTask

并设置优先级为MAX NotificationManager.IMPORTANCE_HIGH

Answer 2

我解决了，问题是Notification ID和Channel ID不一样

为什么没有出现通知？

Why doesn't the notification appear?

notifications

android

foreground-service