post 频道空通知失败 Android
Failed to post notification on channel null in Android
我正在开发一个 android 应用程序，我试图在设置特定时间时显示通知。
我可以看到出现了一个错误
"Failed to post notification on channel null"
我已附上代码以供参考。
这是WorkReminder.java
WorkReminder.java
public class WorkReminder extends AppCompatActivity implements View.OnClickListener{
private int notificationId = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_work_reminder);
getSupportActionBar().setTitle("Create reminders");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
findViewById(R.id.set_button).setOnClickListener(this);
findViewById(R.id.cancel_button).setOnClickListener(this);
}
@Override
public void onClick(View v) {
EditText reminder = findViewById(R.id.reminder_text);
TimePicker timePicker = findViewById(R.id.timePicker);
// Set notificationId & text.
Intent intent = new Intent(WorkReminder.this, AlarmReceiver.class);
intent.putExtra("notificationId", notificationId);
intent.putExtra("todo", reminder.getText().toString());
// getBroadcast(context, requestCode, intent, flags)
PendingIntent alarmIntent = PendingIntent.getBroadcast(WorkReminder.this, 0,
intent, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager alarm = (AlarmManager) getSystemService(ALARM_SERVICE);
switch (v.getId()) {
case R.id.set_button:
int hour = timePicker.getCurrentHour();
int minute = timePicker.getCurrentMinute();
// Create time.
Calendar startTime = Calendar.getInstance();
startTime.set(Calendar.HOUR_OF_DAY, hour);
startTime.set(Calendar.MINUTE, minute);
startTime.set(Calendar.SECOND, 0);
long alarmStartTime = startTime.getTimeInMillis();
// Set alarm.
// set(type, milliseconds, intent)
alarm.set(AlarmManager.RTC_WAKEUP, alarmStartTime, alarmIntent);
Toast.makeText(this, "Done!", Toast.LENGTH_SHORT).show();
break;
case R.id.cancel_button:
alarm.cancel(alarmIntent);
Toast.makeText(this, "Canceled.", Toast.LENGTH_SHORT).show();
break;
}
}
}
这是AlarmReceiver.java
AlarmReceiver.java
public class AlarmReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// Get id & message from intent.
int notificationId = intent.getIntExtra("notificationId", 0);
String message = intent.getStringExtra("todo");
// When notification is tapped, call MainActivity.
Intent mainIntent = new Intent(context, MainActivity.class);
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, mainIntent, 0);
NotificationManager myNotificationManager =
(NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
// Prepare notification.
Notification.Builder builder = new Notification.Builder(context);
builder.setSmallIcon(android.R.drawable.ic_dialog_info)
.setContentTitle("Reminder!")
.setContentText(message)
.setWhen(System.currentTimeMillis())
.setAutoCancel(true)
.setContentIntent(contentIntent)
.setPriority(Notification.PRIORITY_MAX)
.setDefaults(Notification.DEFAULT_ALL);
// Notify
myNotificationManager.notify(notificationId, builder.build());
}
}
这是activity_work_reminder.xml
activity_work_reminder.xml
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".WorkReminder">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/reminder_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:gravity="center_horizontal"
android:lineSpacingExtra="3dp"
android:text="Staying hygiene is more important during COVID - 19. Ensure your safety by creating simple reminders to keep you noted."
android:textAlignment="center"
android:textColor="#000"
android:textSize="18dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/reminder_text"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="28dp"
android:background="@drawable/corner_edges"
android:ems="10"
android:hint="Reminder"
android:inputType="textPersonName"
android:padding="15dp"
android:textColor="#000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.18"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/reminder_header" />
<TimePicker
android:id="@+id/timePicker"
android:layout_width="300dp"
android:layout_height="400dp"
android:layout_marginTop="32dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.495"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/reminder_text" />
<Button
android:id="@+id/set_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:text="set reminder"
android:padding="12dp"
android:background="@drawable/corner_edges"
app:layout_constraintEnd_toStartOf="@+id/cancel_button"
app:layout_constraintHorizontal_bias="0.603"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/timePicker" />
<Button
android:id="@+id/cancel_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:layout_marginEnd="76dp"
android:layout_marginRight="76dp"
android:text="cancel"
android:padding="12dp"
android:background="@drawable/corner_edges"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="@+id/timePicker" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
给我一个显示通知的方法。
您需要在发布通知之前创建通知渠道。请发现文档。
https://developer.android.com/training/notify-user/build-notification#java
Before you can deliver the notification on Android 8.0 and higher, you must register your app's notification channel with the system by passing an instance of NotificationChannel to createNotificationChannel(). So the following code is blocked by a condition on the SDK_INT version:
private void createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
CharSequence name = getString(R.string.channel_name);
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);
channel.setDescription(description);
// Register the channel with the system; you can't change the importance
// or other notification behaviors after this
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}}
我正在开发一个 android 应用程序，我试图在设置特定时间时显示通知。
我可以看到出现了一个错误
"Failed to post notification on channel null"
我已附上代码以供参考。 这是WorkReminder.java
WorkReminder.java
public class WorkReminder extends AppCompatActivity implements View.OnClickListener{
private int notificationId = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_work_reminder);
getSupportActionBar().setTitle("Create reminders");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
findViewById(R.id.set_button).setOnClickListener(this);
findViewById(R.id.cancel_button).setOnClickListener(this);
}
@Override
public void onClick(View v) {
EditText reminder = findViewById(R.id.reminder_text);
TimePicker timePicker = findViewById(R.id.timePicker);
// Set notificationId & text.
Intent intent = new Intent(WorkReminder.this, AlarmReceiver.class);
intent.putExtra("notificationId", notificationId);
intent.putExtra("todo", reminder.getText().toString());
// getBroadcast(context, requestCode, intent, flags)
PendingIntent alarmIntent = PendingIntent.getBroadcast(WorkReminder.this, 0,
intent, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager alarm = (AlarmManager) getSystemService(ALARM_SERVICE);
switch (v.getId()) {
case R.id.set_button:
int hour = timePicker.getCurrentHour();
int minute = timePicker.getCurrentMinute();
// Create time.
Calendar startTime = Calendar.getInstance();
startTime.set(Calendar.HOUR_OF_DAY, hour);
startTime.set(Calendar.MINUTE, minute);
startTime.set(Calendar.SECOND, 0);
long alarmStartTime = startTime.getTimeInMillis();
// Set alarm.
// set(type, milliseconds, intent)
alarm.set(AlarmManager.RTC_WAKEUP, alarmStartTime, alarmIntent);
Toast.makeText(this, "Done!", Toast.LENGTH_SHORT).show();
break;
case R.id.cancel_button:
alarm.cancel(alarmIntent);
Toast.makeText(this, "Canceled.", Toast.LENGTH_SHORT).show();
break;
}
}
}
这是AlarmReceiver.java
AlarmReceiver.java
public class AlarmReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// Get id & message from intent.
int notificationId = intent.getIntExtra("notificationId", 0);
String message = intent.getStringExtra("todo");
// When notification is tapped, call MainActivity.
Intent mainIntent = new Intent(context, MainActivity.class);
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, mainIntent, 0);
NotificationManager myNotificationManager =
(NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
// Prepare notification.
Notification.Builder builder = new Notification.Builder(context);
builder.setSmallIcon(android.R.drawable.ic_dialog_info)
.setContentTitle("Reminder!")
.setContentText(message)
.setWhen(System.currentTimeMillis())
.setAutoCancel(true)
.setContentIntent(contentIntent)
.setPriority(Notification.PRIORITY_MAX)
.setDefaults(Notification.DEFAULT_ALL);
// Notify
myNotificationManager.notify(notificationId, builder.build());
}
}
这是activity_work_reminder.xml
activity_work_reminder.xml
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".WorkReminder">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/reminder_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:gravity="center_horizontal"
android:lineSpacingExtra="3dp"
android:text="Staying hygiene is more important during COVID - 19. Ensure your safety by creating simple reminders to keep you noted."
android:textAlignment="center"
android:textColor="#000"
android:textSize="18dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@+id/reminder_text"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="28dp"
android:background="@drawable/corner_edges"
android:ems="10"
android:hint="Reminder"
android:inputType="textPersonName"
android:padding="15dp"
android:textColor="#000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.18"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/reminder_header" />
<TimePicker
android:id="@+id/timePicker"
android:layout_width="300dp"
android:layout_height="400dp"
android:layout_marginTop="32dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.495"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/reminder_text" />
<Button
android:id="@+id/set_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:text="set reminder"
android:padding="12dp"
android:background="@drawable/corner_edges"
app:layout_constraintEnd_toStartOf="@+id/cancel_button"
app:layout_constraintHorizontal_bias="0.603"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/timePicker" />
<Button
android:id="@+id/cancel_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:layout_marginEnd="76dp"
android:layout_marginRight="76dp"
android:text="cancel"
android:padding="12dp"
android:background="@drawable/corner_edges"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="@+id/timePicker" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
给我一个显示通知的方法。
您需要在发布通知之前创建通知渠道。请发现文档。
https://developer.android.com/training/notify-user/build-notification#java
Before you can deliver the notification on Android 8.0 and higher, you must register your app's notification channel with the system by passing an instance of NotificationChannel to createNotificationChannel(). So the following code is blocked by a condition on the SDK_INT version:
private void createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
CharSequence name = getString(R.string.channel_name);
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);
channel.setDescription(description);
// Register the channel with the system; you can't change the importance
// or other notification behaviors after this
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}}