使用 Kotlin 在 Android 中创建通知

2022-07-28  本文已影响0人  小城哇哇

步骤

创建通知

NotificationUtils、EggTimerViewModel、EggTimerFragment

基本通知

// NotificationUtils.kt

package com.example.android.eggtimernotifications.util

import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.graphics.BitmapFactory
import androidx.core.app.NotificationCompat
import com.example.android.eggtimernotifications.MainActivity
import com.example.android.eggtimernotifications.R
import com.example.android.eggtimernotifications.receiver.SnoozeReceiver

// Notification ID.
private val NOTIFICATION_ID = 0
private val REQUEST_CODE = 0
private val FLAGS = 0

// Step 1.1 extension function to send messages (GIVEN)
/**
 * Builds and delivers the notification.
 *
 * @param context, activity context.
 */
fun NotificationManager.sendNotification(messageBody: String, applicationContext: Context) {
    // Create the content intent for the notification, which launches
    // this activity
    // TODO: Step 1.11 create intent

    // TODO: Step 1.12 create PendingIntent

    // TODO: Step 2.0 add style

    // TODO: Step 2.2 add snooze action

    // TODO: Step 1.2 get an instance of NotificationCompat.Builder
    // Build the notification
    val builder = NotificationCompat.Builder(
        applicationContext,
        applicationContext.getString(R.string.egg_notification_channel_id)
    )

    // TODO: Step 1.8 use the new 'breakfast' notification channel

    // TODO: Step 1.3 set title, text and icon to builder
        .setSmallIcon(R.drawable.cooked_egg)
        .setContentTitle(applicationContext
            .getString(R.string.notification_title))
        .setContentText(messageBody)

    // TODO: Step 1.13 set content intent

        // TODO: Step 2.1 add style to builder

        // TODO: Step 2.3 add snooze action

        // TODO: Step 2.5 set priority

    // TODO: Step 1.4 call notify
    notify(NOTIFICATION_ID, builder.build())
}

// TODO: Step 1.14 Cancel all notifications

package com.example.android.eggtimernotifications.ui

import android.app.*
import android.content.Context
import android.content.Intent
import android.os.CountDownTimer
import android.os.SystemClock
import androidx.core.app.AlarmManagerCompat
import androidx.core.content.ContextCompat
import androidx.lifecycle.*
import com.example.android.eggtimernotifications.receiver.AlarmReceiver
import com.example.android.eggtimernotifications.R
import com.example.android.eggtimernotifications.util.sendNotification
import kotlinx.coroutines.*

class EggTimerViewModel(private val app: Application) : AndroidViewModel(app) {

    private val REQUEST_CODE = 0
    private val TRIGGER_TIME = "TRIGGER_AT"

    private val minute: Long = 60_000L
    private val second: Long = 1_000L

    private val timerLengthOptions: IntArray
    private val notifyPendingIntent: PendingIntent

    private val alarmManager = app.getSystemService(Context.ALARM_SERVICE) as AlarmManager
    private var prefs = app.getSharedPreferences(
                        "com.example.android.eggtimernotifications",
                        Context.MODE_PRIVATE
        )
    private val notifyIntent = Intent(app, AlarmReceiver::class.java)

    private val _timeSelection = MutableLiveData<Int>()
    val timeSelection: LiveData<Int>
        get() = _timeSelection

    private val _elapsedTime = MutableLiveData<Long>()
    val elapsedTime: LiveData<Long>
        get() = _elapsedTime

    private var _alarmOn = MutableLiveData<Boolean>()
    val isAlarmOn: LiveData<Boolean>
        get() = _alarmOn

    private lateinit var timer: CountDownTimer

    init {
        _alarmOn.value = PendingIntent.getBroadcast(
            getApplication(),
            REQUEST_CODE,
            notifyIntent,
            PendingIntent.FLAG_NO_CREATE
        ) != null

        notifyPendingIntent = PendingIntent.getBroadcast(
            getApplication(),
            REQUEST_CODE,
            notifyIntent,
            PendingIntent.FLAG_UPDATE_CURRENT
        )

        timerLengthOptions = app.resources.getIntArray(R.array.minutes_array)

        //If alarm is not null, resume the timer back for this alarm
        if (_alarmOn.value!!) {
            createTimer()
        }

    }

    /**
     * Turns on or off the alarm
     *
     * @param isChecked, alarm status to be set.
     */
    fun setAlarm(isChecked: Boolean) {
        when (isChecked) {
            true -> timeSelection.value?.let { startTimer(it) }
            false -> cancelNotification()
        }
    }

    /**
     * Sets the desired interval for the alarm
     *
     * @param timerLengthSelection, interval timerLengthSelection value.
     */
    fun setTimeSelected(timerLengthSelection: Int) {
        _timeSelection.value = timerLengthSelection
    }

    /**
     * Creates a new alarm, notification and timer
     */
    private fun startTimer(timerLengthSelection: Int) {
        _alarmOn.value?.let {
            if (!it) {
                _alarmOn.value = true
                val selectedInterval = when (timerLengthSelection) {
                    0 -> second * 10 //For testing only
                    else ->timerLengthOptions[timerLengthSelection] * minute
                }
                val triggerTime = SystemClock.elapsedRealtime() + selectedInterval

                // Step 1.5 get an instance of NotificationManager and call sendNotification
                val notificationManager = ContextCompat.getSystemService(                       
                    app,                                                                        
                    NotificationManager::class.java                                             
                ) as NotificationManager                                                        
                notificationManager.sendNotification(app.getString(R.string.timer_running), app)

                              // Step 1.15 call cancel notification

                AlarmManagerCompat.setExactAndAllowWhileIdle(
                    alarmManager,
                    AlarmManager.ELAPSED_REALTIME_WAKEUP,
                    triggerTime,
                    notifyPendingIntent
                )

                viewModelScope.launch {
                    saveTime(triggerTime)
                }
            }
        }
        createTimer()
    }

    /**
     * Creates a new timer
     */
    private fun createTimer() {
        viewModelScope.launch {
            val triggerTime = loadTime()
            timer = object : CountDownTimer(triggerTime, second) {
                override fun onTick(millisUntilFinished: Long) {
                    _elapsedTime.value = triggerTime - SystemClock.elapsedRealtime()
                    if (_elapsedTime.value!! <= 0) {
                        resetTimer()
                    }
                }

                override fun onFinish() {
                    resetTimer()
                }
            }
            timer.start()
        }
    }

    /**
     * Cancels the alarm, notification and resets the timer
     */
    private fun cancelNotification() {
        resetTimer()
        alarmManager.cancel(notifyPendingIntent)
    }

    /**
     * Resets the timer on screen and sets alarm value false
     */
    private fun resetTimer() {
        timer.cancel()
        _elapsedTime.value = 0
        _alarmOn.value = false
    }

    private suspend fun saveTime(triggerTime: Long) =
        withContext(Dispatchers.IO) {
            prefs.edit().putLong(TRIGGER_TIME, triggerTime).apply()
        }

    private suspend fun loadTime(): Long =
        withContext(Dispatchers.IO) {
            prefs.getLong(TRIGGER_TIME, 0)
        }
}

通知渠道

// EggTimerFragment.kt

package com.example.android.eggtimernotifications.ui

import android.app.NotificationChannel
import android.app.NotificationManager
import android.graphics.Color
import android.os.Build
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.lifecycle.ViewModelProvider
import com.example.android.eggtimernotifications.R
import com.example.android.eggtimernotifications.databinding.FragmentEggTimerBinding
import com.google.firebase.messaging.FirebaseMessaging

class EggTimerFragment : Fragment() {

    private val TOPIC = "breakfast"

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        val binding: FragmentEggTimerBinding = DataBindingUtil.inflate(
            inflater, R.layout.fragment_egg_timer, container, false
        )

        val viewModel = ViewModelProvider(this).get(EggTimerViewModel::class.java)

        binding.eggTimerViewModel = viewModel
        binding.lifecycleOwner = this.viewLifecycleOwner

        // Step 1.7 call create channel
        createChannel(
            getString(R.string.egg_notification_channel_id),
            getString(R.string.egg_notification_channel_name)
        )

        return binding.root
    }

    private fun createChannel(channelId: String, channelName: String) {
        // Step 1.6 START create a channel
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val notificationChannel = NotificationChannel(
                channelId,
                channelName,
                // Change importance
                NotificationManager.IMPORTANCE_LOW
            )

            notificationChannel.enableLights(true)
            notificationChannel.lightColor = Color.RED
            notificationChannel.enableVibration(true)
            notificationChannel.description = "Time for breakfast!"

            val notificationManager = requireActivity().getSystemService(
                NotificationManager::class.java
            )
            notificationManager.createNotificationChannel(notificationChannel)

        } else {
            Log.d(TAG, "VERSION.SDK_INT < O")
            Toast.makeText(context, "VERSION.SDK_INT < O", Toast.LENGTH_SHORT).show()
        }

        // Step 1.6 END create a channel

    }

    companion object {
        private const val TAG = "EggTimerFragment"
        fun newInstance() = EggTimerFragment()
    }
}

添加新通知

报警接收器

向您的应用添加通知

package com.example.android.eggtimernotifications.receiver

import android.app.NotificationManager
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.widget.Toast
import androidx.core.content.ContextCompat
import com.example.android.eggtimernotifications.R
import com.example.android.eggtimernotifications.util.sendNotification

class AlarmReceiver: BroadcastReceiver() {

    override fun onReceive(context: Context, intent: Intent) {
        // Step 1.10 remove toast (since we're now sending a notification for the same)
        // Toast.makeText(context, context.getText(R.string.eggs_ready), Toast.LENGTH_SHORT).show()

        // TODO: Step 1.9 add call to sendNotification
        val notificationManager = ContextCompat.getSystemService(
            context,
            NotificationManager::class.java
        ) as NotificationManager

                notificationManager.sendNotification(
            context.getText(R.string.eggs_ready).toString(),
            context
        )

    }

}

使用 PendingIntent 从通知返回到应用程序

通知工具

添加内容意图

使用 cancelAll 清除以前的通知

NotificationUtils, EggTimerViewModel

取消通知

样式化您的通知

通知工具

添加贪睡动作

贪睡接收器，NotificationUtils

改变重要性

EggTimerFragment、NotificationUtils

通知徽章

EggTimerFragment

链接：https://dev.to/apigeoneer/creating-notifications-in-android-with-kotlin-56fi

上一篇下一篇

猜你喜欢

热点阅读