Qt Android Notifier▲

Image non disponible

This example demonstrates how to add a custom Java class to an Android application, and how to call it using the JNI convenience APIs in Qt.

Click on one of the smiley faces to send a notification in the status bar of the Android screen.

Running the Example▲

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Calling Java Methods from C++ Code▲

We define a custom Java class called NotificationClient in the NotificationClient.java file:

 
Sélectionnez
package org.qtproject.example.androidnotifier;

import android.app.Notification;
import android.app.NotificationManager;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.BitmapFactory;
import android.app.NotificationChannel;

public class NotificationClient
{
    public static void notify(Context context, String message) {
        try {
            NotificationManager m_notificationManager = (NotificationManager)
                    context.getSystemService(Context.NOTIFICATION_SERVICE);

            Notification.Builder m_builder;
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
                int importance = NotificationManager.IMPORTANCE_DEFAULT;
                NotificationChannel notificationChannel;
                notificationChannel = new NotificationChannel("Qt", "Qt Notifier", importance);
                m_notificationManager.createNotificationChannel(notificationChannel);
                m_builder = new Notification.Builder(context, notificationChannel.getId());
            } else {
                m_builder = new Notification.Builder(context);
            }

            Bitmap icon = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon);
            m_builder.setSmallIcon(R.drawable.icon)
                    .setLargeIcon(icon)
                    .setContentTitle("A message from Qt!")
                    .setContentText(message)
                    .setDefaults(Notification.DEFAULT_SOUND)
                    .setColor(Color.GREEN)
                    .setAutoCancel(true);

            m_notificationManager.notify(0, m_builder.build());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the NotificationClient C++ class header file, notificationclient.h, we declare a simple C++ API to display notifications on an Android device. It consists of a single string property, notification, and a slot, updateAndroidNotification(), that calls the Java code:

 
Sélectionnez
class NotificationClient : public QObject
{
    Q_OBJECT
public:
    explicit NotificationClient(QObject *parent = 0);

    void setNotification(const QString &notification);
    QString notification() const;

signals:
    void notificationChanged();

private slots:
    void updateAndroidNotification();

private:
    QString m_notification;
};

We connect the notificationChanged() signal to the updateAndroidNotification() slot to update the notification text when the notification text changes:

 
Sélectionnez
    m_notification = notification;
    emit notificationChanged();

The updateAndroidNotification() function calls the Java method responsible for sending the notification from the Android platform APIs. First, we construct a Java string jstring from the notification string, then pass the jstring object as a parameter to the notify() method in Java:

 
Sélectionnez
void NotificationClient::updateAndroidNotification()
{
    QJniObject javaNotification = QJniObject::fromString(m_notification);
    QJni