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Android java app with notification from asp.net mvc using firebase cloud messaging – part 3

Notification service in Android

Now we need to create in Android the service able to manage the notification incoming from firebase and to show these to user. Follow this usefull article Working easily with FCM push notifications in Android. You’ll have a class like this.

package com.mycompany.myfirstapp;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import androidx.core.app.NotificationCompat;
import android.util.Log;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

import androidx.core.app.NotificationManagerCompat;
import androidx.work.OneTimeWorkRequest;
import androidx.work.WorkManager;

//is the class that we can find in the manifest as a service

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    public static final String TAG = "MsgFirebaseServ";

    @Override


    public void onMessageReceived(RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);

        String title = "";
        String body = "";
        String objectId = "";
        String objectType = "";

        if (remoteMessage.getData() != null) {
            title = remoteMessage.getData().get("title");
            body = remoteMessage.getData().get("body");
            objectId = remoteMessage.getData().get("object_id");
            objectType = remoteMessage.getData().get("objectType");
        }

        Notification notification = new NotificationCompat.Builder(this)
                .setContentTitle(title)
                .setContentText(body)
                .build();
        NotificationManagerCompat manager = NotificationManagerCompat.from(getApplicationContext());
        manager.notify(/*notification id*/0, notification);
    }
}

Run your app on your device

Follow this instruction : https://developer.android.com/training/basics/firstapp/running-app

First test using your app in your device

  • Run the app on your device or emulator. The app should had created a new register id for the device and send it to asp.net mvc site. Now the device is registered.
  • Open Firebase console, go down in the menu on the left. Open Cloud Messaging session : you should find the possibility to send notification to your device starting from this page. So you can test correct developing of above class.

Send notification from asp.net mvc to firebase

For backend developers. You should create a class to manage notification to firebase. Follow the article Firebase push notifications using a .NET Backend to prepare a class to manage the notification to Firebase.

Then prepare your notification test task in a controller. Something like this :

        public Task<bool> NoteAsync()
        {
            var device = db.RegisteredDevices.Where(d => d.ENABLED == true);
            string[] da = new string[device.Count()];
            int i = 0;
            foreach (RegDevice r in device)
            {
                da[i] = r.ID;
                i++;     
            }
            string serverkey = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
            return FCMPushNotification.SendPushNotification(da,serverkey,"Title","body");
        }

Firebase messaging, where to get Server Key?

Click the Settings (Cog wheel) icon next to your project name at the top of the new Firebase Console, as per screenshot below:

  1. Click Project settings.
  2. Click on the Cloud Messaging tab.


Final test

Call the asp.net mvc method created. You should see a notification in your device.


Android java app with notification from asp.net mvc using firebase cloud messaging – part 1

Android java app with notification from asp.net mvc using firebase cloud messaging – part 2

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Android java app with notification from asp.net mvc using firebase cloud messaging – part 2

In this scenario we looking to send the device registration id to a server with user data to save it in our database.

Token based authentication in ASP.NET Web API

For backend developers. ASP.NET Web API is a framework that makes it easy to build HTTP services that reach a broad range of clients. Follow the following article in order to implement Token based authentication using ASP.NET Web API 2. (Part 1 : Token based authentication in ASP.NET Web API)

To register the device you need a method like this

       [HttpPost]
       public HttpResponseMessage Register(string key)
        {
            
            var identity = (ClaimsIdentity)User.Identity;
            string message = "";
            if (!string.IsNullOrEmpty(key))
            {
                var userid = identity.GetUserId();
                RegDevice device = db.RegisteredDevices.Where(d => d.ID == key &&
                        d.USER == userid).FirstOrDefault();
                        if (device == null)
                        {
                            device = new RegDevice();
                            device.ID = key;
                            device.USER = userid;
                            db.RegisteredDevices.Add(device);
                            if (db.SaveChanges() > 0)
                                {
                                    return Request.CreateResponse(HttpStatusCode.OK);
                                }
                                else
                                {
                                    message = Vocabolario.ErrorInTemporaryStorage;
                                    //System.Diagnostics.Debug.WriteLine("PostServerLog. erore" + 
                                    message);
                                }
                        }  
            }
            HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.BadRequest, "value");
            response.Content = new StringContent(message, Encoding.Unicode);
            return response;
        }

Bearer authentication on Java

For frontend developers. To authenticated in a asp.net mvc site, first of all you have to generate the token using the username and the password. The token will conserve all the user’s data more the validation time. We will use this token to talk to our server.

Getting a token is not a goal per se. It’s a necessary step to call a protected API. The token needs to be used to access a Web API. The way to do it is by setting the Authorization header to be “Bearer”, followed by a space, followed by the access token.

To generate the token you should use something like this :

package com.mycompany.myfirstapp;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;

import javax.net.ssl.HttpsURLConnection;

import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import java.io.InputStream;
import org.apache.wink.json4j.JSONArray;
import org.apache.wink.json4j.JSONObject;
import org.apache.wink.json4j.JSONException;

import java.nio.charset.StandardCharsets;

import java.security.cert.Certificate;
import javax.net.ssl.SSLPeerUnverifiedException;

public class MyServer {

    private final static String BASE_URL = "https://www.mysite.com";
    private final static String TOKEN_ENDPOINT = BASE_URL + "/token";
    private final static String REGDEVICE_ENDPOINT = BASE_URL + "/api/Account/Register";

//pass username and password in this example
    public static String getToken(String user, String pwd) throws IOException, JSONException {
        byte[] postData = getRequestBodyForAccessToken(user,pwd);
        int postDataLength = postData.length;

        URL url = new URL(TOKEN_ENDPOINT);
        HttpsURLConnection requestConn = (HttpsURLConnection) url.openConnection();
        requestConn.setRequestMethod("POST");
        requestConn.setDoOutput(true);
        requestConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        try (DataOutputStream dos = new DataOutputStream(requestConn.getOutputStream())) {
            dos.write(postData);
        }

        if (requestConn.getResponseCode() != HttpURLConnection.HTTP_OK) {
            if (requestConn.getResponseCode() == HttpURLConnection.HTTP_MOVED_PERM) {
                String serverURL = requestConn.getHeaderField("Location");
                System.err.println("Set the value of the server path to: " + serverURL);
            }
            System.err.println("Error in obtaining an access token. " + 
            requestConn.getResponseMessage());
        }

        String accessToken;
        try (InputStream tokenStream = requestConn.getInputStream()) {
            JSONObject tokenRes = new JSONObject(tokenStream);
            accessToken = (String) tokenRes.get("access_token");
        }
        return accessToken;
    }

    public static void RegisterNewDevice(String deviceKey, String atoken)
    {
        StringBuilder urlBuilder = new StringBuilder(REGDEVICE_ENDPOINT);
        urlBuilder.append("&key=").append(deviceKey);
        String pathWithQueryParams = urlBuilder.toString();
        
        InputStream restRegApiStream = null;
        try {
            HttpsURLConnection restRegApiConn = getRestApiConnection(pathWithQueryParams);
            addAuthenticationHeader(restRegApiConnn, atoken);
            restRegApiConn.setRequestMethod("POST");
            
            if (restRegApiConn.getResponseCode() != HttpURLConnection.HTTP_OK) {
                if (restRegApiConn.getResponseCode() == HttpURLConnection.HTTP_UNAUTHORIZED) {
                    if (restRegApiConn.getHeaderField("www-authenticate").contains("invalid_token")) {
                       
                    }
                } else if (restRegApiConn.getResponseCode() == HttpURLConnection.HTTP_FORBIDDEN) {
                    
                }
                
            } else {
                restRegApiStream = restRegApiConn.getInputStream();
            }
        }
        catch(Exception ex)
        {

        }
    }

    private static HttpsURLConnection getRestApiConnection(String apiCall) throws IOException {
        URL restApiUrl = new URL(apiCall);
        HttpsURLConnection restApiURLConnection = (HttpsURLConnection) restApiUrl.openConnection();
        return restApiURLConnection;
    }

    private static void addAuthenticationHeader(HttpsURLConnection restApiURLConnection, String t) 
    {
        restApiURLConnection.setRequestProperty("Authorization", "Bearer " + t);
    }

    /**
     * Get the request body to be used for the POST request when requesting an access token.
     */
    private static byte[] getRequestBodyForAccessToken(String user, String pwd) {
        StringBuilder sb = new StringBuilder("grant_type=password");
        sb.append("&username=")
                .append(user)
                .append("&password=")
                .append(pwd);
        return sb.toString().getBytes(StandardCharsets.UTF_8);
    }

    private static void print_https_cert(HttpsURLConnection con){

        if(con!=null){

            try {

                System.out.println("Response Code : " + con.getResponseCode());
                System.out.println("Cipher Suite : " + con.getCipherSuite());
                System.out.println("\n");

                Certificate[] certs = con.getServerCertificates();
                for(Certificate cert : certs){
                    System.out.println("Cert Type : " + cert.getType());
                    System.out.println("Cert Hash Code : " + cert.hashCode());
                    System.out.println("Cert Public Key Algorithm : "
                            + cert.getPublicKey().getAlgorithm());
                    System.out.println("Cert Public Key Format : "
                            + cert.getPublicKey().getFormat());
                    System.out.println("\n");
                }

            } catch (SSLPeerUnverifiedException e) {
                e.printStackTrace();
            } catch (IOException e){
                e.printStackTrace();
            }

        }

    }

    private static void print_content(HttpsURLConnection con){
        if(con!=null){

            try {

                System.out.println("****** Content of the URL ********");
                BufferedReader br =
                        new BufferedReader(
                                new InputStreamReader(con.getInputStream()));

                String input;

                while ((input = br.readLine()) != null){
                    System.out.println(input);
                }
                br.close();

            } catch (IOException e) {
                e.printStackTrace();
            }

        }

    }
}

So now you have registered the device on the server. It’s time to send notification to your device


Android java app with notification from asp.net mvc using firebase cloud messaging – part 1

Android java app with notification from asp.net mvc using firebase cloud messaging – part 3

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Android java app with notification from asp.net mvc using firebase cloud messaging – part 1

Firebase Project

For backend developers.

Follow the document : https://firebase.google.com/docs/android/setup

Important steps : Add Firebase using the Firebase console. After you have a Firebase project, you can add your Android app to it. Enter your app’s package name in the Android package name field. Click Download google-services.json to obtain your Firebase Android config file google-services.json)

Android app in java

For frontend developers

  • Install or update Android Studio to its latest version.
  • Make sure that your app meets the following requirements:
    • Targets API level 16 (Jelly Bean) or later
    • Uses Gradle 4.1 or later

In Android Studio create a new android app using java as language. To enable Firebase products in your app, pass to Project visualization (on the left of android studio) in your root-level Gradle file (build.gradle), add rules to include the Google Services Gradle plugin. Check that you have Google’s Maven repository, as well.

buildscript {

  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
  }

  dependencies {
    // ...

    // Add the following line:
    classpath 'com.google.gms:google-services:4.3.3'  // Google Services plugin
  }
}

allprojects {
  // ...

  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
    // ...
  }
}

In your module (app-level) Gradle file (usually app/build.gradle), apply the Google Services Gradle plugin:

apply plugin: 'com.android.application'
// Add the following line:
apply plugin: 'com.google.gms.google-services'  // Google Services plugin

android {
  // ...
}

To your module (app-level) Gradle file (usually app/build.gradle), add the dependencies for the Firebase products that you want to use in your app.

dependencies {
  // ...

  // Add the SDKs for the Firebase products you want to use in your app
  // For example, to use Firebase Authentication and Cloud Firestore
  implementation 'com.google.firebase:firebase-analytics:17.2.0'
  implementation 'com.google.firebase:firebase-messaging:20.1.0'

  // Getting a "Could not find" error? Make sure that you've added
  // Google's Maven repository to your root-level build.gradle file
}

Sync your app (at the top on the right of Android Studio) to ensure that all dependencies have the necessary versions.

Set up a Firebase Cloud Messaging client app on Android

For frontend developers. Follow the document : https://firebase.google.com/docs/cloud-messaging/android/client

Edit your app manifest. A service that extends FirebaseMessagingService. This is required if you want to do any message handling beyond receiving notifications

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

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE"/>
    <uses-permission android:name="android.permission.WAKE_LOCK"/>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <uses-permission android:name="android.permission.VIBRATE" />
    <permission
        android:name="${applicationId}.permission.C2D_MESSAGE"
        android:protectionLevel="signature"/>
    <uses-permission android:name="${applicationId}.permission.C2D_MESSAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:networkSecurityConfig="@xml/network_security_config"
        tools:ignore="GoogleAppIndexingWarning">
        <!-- [START fcm_default_icon] -->
        <!-- Set custom default icon. This is used when no icon is set for incoming notification messages. -->
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_stat_ic_notification" />
        <!-- Set color used with incoming notification messages. This is used when no color is set for the incoming notification message. -->
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_color"
            android:resource="@color/colorAccent" />
        <!-- [END fcm_default_icon] -->
        <!-- [START fcm_disable_auto_init] -->
        <meta-data
            android:name="firebase_messaging_auto_init_enabled"
            android:value="false" />
        <meta-data
            android:name="firebase_analytics_collection_enabled"
            android:value="false" />
        <!-- [END fcm_disable_auto_init] -->
        <activity
            android:name=".EntryChoiceActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!-- [START firebase_service] -->
        <service
            android:name=".MyFirebaseMessagingService"
            android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
        <!-- [END firebase_service] -->
    </application>

</manifest>

Access the device registration token

On initial startup of your app, the FCM SDK generates a registration token for the client app instance.

The registration token may change when:

  • The app deletes Instance ID
  • The app is restored on a new device
  • The user uninstalls/reinstall the app
  • The user clears app data.

When you need to retrieve the current token, call FirebaseInstanceId.getInstance().getInstanceId(): For example

private void GetRegistrationToken()
    {
        FirebaseInstanceId.getInstance().getInstanceId()
                .addOnCompleteListener(new OnCompleteListener<InstanceIdResult>() {
                    @Override
                    public void onComplete(@NonNull Task<InstanceIdResult> task) {
                        if (!task.isSuccessful()) {
                            Log.w(TAG, "getInstanceId failed", task.getException());
                            return;
                        }

                        // Get new Instance ID token
                        String token = task.getResult().getToken();
                        regToken = token;
                        System.out.println("***************");
                        System.out.println(token);
                        //
                        // Log and toast
                        String msg = getString(R.string.msg_token_fmt, token);
                        Log.d(TAG, msg);
                        Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();

                        //
                        new Thread(){
                            public void run(){
                                try {
                                    //SEND REGISTRATION TOKEN TO BACKEND SERVER
                                catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }
                        }.start();
                        //

                    }
                });
    }

As you can see above, after get the registration id you need to pass this to your backend server. In this way you will be able to save this data linking it to your user to permit, in the future, to send message only to selected users.


Android java app with notification from asp.net mvc using firebase cloud messaging – part 2

Android java app with notification from asp.net mvc using firebase cloud messaging – part 3

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ASP.NET MVC EMAIL FROM SITE AND FORGOT PASSWORD

Our site needs to send emails to its users, for example when the user forgets the password. To do this comes to the rescue System.Net.Mail.SmtpClient class.

This class automatically uses the SMTP server settings stored in the Web.config file. You just have to add to that file the following tags inside the configuration tag:

<system.net>
 <mailSettings>
 <smtp deliveryMethod="Network" from="mail_from">
 <network host="my_smtp_server" port="my_smtp_server_port" userName="user_name_smtp" password="password" clientDomain="my_domain" />
 </smtp>
 </mailSettings>
 </system.net>

FORGOT DIMENTICATA

In the view Account/Login , you can see, bottom, on the left, the link to Account/ForgotPassword that is the page where the user can reset his password.

In the  controller Account, in the action post  “ForgotPassword” you make operational, removing them as a comment, the lines of code dedicated to password recovery.

In the file IdentityConfig.cs, in the function

public Task SendAsync(IdentityMessage message)

and replaced to the line

return Task.FromResult(0);

with the following lines of code

var sentFrom = "myemail@mydomain.com"
 //
 System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient();
 //
 client.EnableSsl = false;

// Create the message:
 var mail =
 new System.Net.Mail.MailMessage(sentFrom, message.Destination);

mail.Subject = message.Subject;
 mail.Body = message.Body;
 mail.IsBodyHtml = true;

// Send:
 return client.SendMailAsync(mail);

You have activated the password recovery

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ASP.NET MVC: SHARED VIEW

The View / Shared folder contains all the visual controls that are to be displayed (used) in different parts of the site: are the old “user controls.” These controls can be called programmatically or called by the site itself automatically.

In this second case, imagine you create the “Student” model. In the View / Shared folder must exist (if not, create them) folders:

  • DisplayTemplates
  • EditorTemplates

If you enter in the 2 folders, 2 view dedicated to the display of “Student” model in two forms of viewing and editing, both named Studente.cshtml, the site will show you your custom control.

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ASP.NET MVC – First Controller

Visual Studio creates the Controller of Model. Let’s see how.

After creating the Model, Student.cs, in the project, in Visual Studio, position yourself on the Controllers directory. Push the right mouse button and press “Add” -> “Controller”. There appears a mask that offers you to choose the type of controller that you want to create. First on the list it is an empty controller, that is, a class that you have to write independently. The third should be a controller of type “Controller with View, using Entity Framework .” Visual Studio, starting with our Model, creates for us the Controller and view all of the CRUD operations. Choose this type.

Now appears a very important mask. From the top you are asked to choose:

  • Model Class. There is a drop-down menu that is automatically filled with all the classes in the Model (and all the classes in your project). Student choose.
  • Date Class context. You must choose the connection to the database that contains your table. The drop down menu shows all the classes in the project, derived from DbContext class,
  • Check “Generate Views” and “use a Page Layout“.
  • Controller name. Visual Studio there proposes a name one based on the Model you’ve selected. You can change the name, but let the word Controller at the end. (Eg. StudentsController)

Before having to set up the Controller, Visual Studio gives you everything you have written in the models and in DbContext is “right.” If the operation is successful now, in the Controllers directory you find the file StudentsController.cs.

Let’s examine this file. You are inside the class StudentsController derived from Controller.

public class StudentsController : Controller
 {
 private ApplicationDbContext db = new ApplicationDbContext();

// GET: Students
 public ActionResult Index()
 {
 return View(db.Students.ToList());
 }

The class immediately initializes a connection to the database (db).

The first function we see is Index(). It ‘was created automatically and allow us to see the list of our students. Each function of this type is called “Action.” When, in our site we require a list of Students, we launch the Index function of the controller Students according to this path:

http://www.mysite.com/Students/Index

The Index function requires, from the connection to the database, all students (db.Students) and turns them into a list (db.Students.ToList ()). At this point sends our list of students to the view (return View (db.Students.ToList ());) As you can see, there isn’t the name of view but only a generic command “View”. The controller  searches in the list of views, for a view  called exactly like the function (Index) and … we see the students.

In the project, in the directory Views, you will find a folder Student with a list of automatically created files (we’ll analyze the view shortly). In the View directory will find the Shared directory. We can say that this directory contains all the “User Controls” ; all interface items that we intend to use in multiple pages; It contains all of the view that are used by other views. Even the one that in the past called “master page” is located here, in the form of “layout”. Look for the _Layout.cshtml file. This is the website of your graphics (we’ll analyze in detail, soon). Find  this piece of code:

<ul class="nav navbar-nav">
 <li>@Html.ActionLink("Home", "Index", "Home")</li>
 <li>@Html.ActionLink("About", "About", "Home")</li>
 <li>@Html.ActionLink("Contact", "Contact", "Home")</li>

These are the buttons you see above, when you launch your site. We need to see a new button to call the student page.

Add to this list html:

<li>@Html.ActionLink("My Student", "Index", "Students")</li>

Then we analyze the ActionLink component.

ActionLink (“Text Displayed”, “Name of Action,” Name of the Controller “). So we will have a button that when pushed will take us to http://www.mysite.com/Students/Index page.

Try running the application and perform a login to test that everything is working.