Android Studio中基于Firebase实现温度状态显示与通知功能问询

Hey Zack, let's break down how to implement all your requirements step by step based on your existing RealtimeData class code:

1. 调整布局：左右分栏展示 #

First, modify your activity_realtime_data.xml to use ConstraintLayout for the split-screen layout (left for Firebase database structure, right for sensor data display):

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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=".RealtimeData">

    <!-- Top Toolbar -->
    <androidx.appcompat.widget.Toolbar
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:layout_constraintTop_toTopOf="parent" />

    <!-- Left Area: Firebase Database Structure -->
    <ScrollView
        android:id="@+id/firebase_db_container"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="8dp"
        android:background="#f5f5f5"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/split_divider"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/app_bar">

        <TextView
            android:id="@+id/db_structure_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="16dp"
            android:text="Firebase Database Structure:\n- sensors\n  - temp: --\n  - humid: --"
            android:textSize="14sp" />
    </ScrollView>

    <!-- Divider Line -->
    <View
        android:id="@+id/split_divider"
        android:layout_width="1dp"
        android:layout_height="0dp"
        android:background="#cccccc"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/data_display_container"
        app:layout_constraintStart_toEndOf="@+id/firebase_db_container"
        app:layout_constraintTop_toBottomOf="@+id/app_bar" />

    <!-- Right Area: Sensor Data Display -->
    <LinearLayout
        android:id="@+id/data_display_container"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="8dp"
        android:orientation="vertical"
        android:padding="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/split_divider"
        app:layout_constraintTop_toBottomOf="@+id/app_bar">

        <!-- Wifi Status Section -->
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:layout_marginBottom="20dp"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/wifi_status"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Wifi status: OFF"
                android:textSize="16sp" />

            <Switch
                android:id="@+id/wifiswitch"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="16dp" />
        </LinearLayout>

        <!-- Temperature Data -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Current Temperature:"
            android:textSize="16sp" />
        <TextView
            android:id="@+id/mTempView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="--°C"
            android:textSize="28sp"
            android:layout_marginBottom="16dp" />

        <!-- Humidity Data -->
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Current Humidity:"
            android:textSize="16sp" />
        <TextView
            android:id="@+id/mHumidView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="--%"
            android:textSize="28sp"
            android:layout_marginBottom="24dp" />

        <!-- Temperature Status Alert -->
        <TextView
            android:id="@+id/temp_status_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Status: --"
            android:textSize="22sp"
            android:textStyle="bold" />
    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

2. 完善RealtimeData类：实时监听与温度状态判断 #

Update your RealtimeData code to add Firebase database listening logic and temperature status judgment:

import android.graphics.Color;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

public class RealtimeData extends AppCompatActivity {
    private DatabaseReference mDatabase;
    private TextView mTempView;
    private TextView mHumidView;
    private TextView tempStatusView;
    private TextView dbStructureText;

    // Wifi Related
    WifiManager wifiManager;
    TextView wifiStatusTextView;
    Switch wifiSwitch;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_realtime_data);
        Toolbar toolbar = findViewById(R.id.app_bar);
        setSupportActionBar(toolbar);

        // Initialize UI Components
        mTempView = findViewById(R.id.mTempView);
        mHumidView = findViewById(R.id.mHumidView);
        tempStatusView = findViewById(R.id.temp_status_view);
        dbStructureText = findViewById(R.id.db_structure_text);

        // Wifi Status Setup
        Toast.makeText(RealtimeData.this, "Make sure device is connected to the internet for latest data", Toast.LENGTH_LONG).show();
        wifiManager = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
        wifiStatusTextView = findViewById(R.id.wifi_status);
        wifiSwitch = findViewById(R.id.wifiswitch);

        updateWifiStatus();
        wifiSwitch.setOnCheckedChangeListener((buttonView, isChecked) -> {
            wifiManager.setWifiEnabled(isChecked);
            updateWifiStatus();
        });

        // Initialize Firebase Database Reference (replace with your node path)
        mDatabase = FirebaseDatabase.getInstance().getReference("sensors");

        // Listen for real-time database changes
        mDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                // Fetch temperature and humidity
                Double temp = snapshot.child("temp").getValue(Double.class);
                Integer humid = snapshot.child("humid").getValue(Integer.class);

                // Update UI with sensor data
                if (temp != null) {
                    mTempView.setText(temp + "°C");
                    // Check temperature status
                    if (temp > 30) {
                        tempStatusView.setText("abnormal");
                        tempStatusView.setTextColor(Color.RED);
                        // You can trigger a notification here if needed
                    } else {
                        tempStatusView.setText("normal");
                        tempStatusView.setTextColor(Color.GREEN);
                    }
                }

                if (humid != null) {
                    mHumidView.setText(humid + "%");
                }

                // Update left panel with database structure
                updateDbStructureDisplay(snapshot);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {
                Toast.makeText(RealtimeData.this, "Failed to load data: " + error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    // Update Wifi status text and switch state
    private void updateWifiStatus() {
        boolean isWifiEnabled = wifiManager.isWifiEnabled();
        wifiStatusTextView.setText(isWifiEnabled ? "Wifi status: ON" : "Wifi status: OFF");
        wifiSwitch.setChecked(isWifiEnabled);
    }

    // Traverse Firebase snapshot and update structure display
    private void updateDbStructureDisplay(DataSnapshot snapshot) {
        StringBuilder sb = new StringBuilder("Firebase Database Structure:\n");
        traverseSnapshot(snapshot, sb, 0);
        dbStructureText.setText(sb.toString());
    }

    // Recursively traverse database nodes
    private void traverseSnapshot(DataSnapshot snapshot, StringBuilder sb, int indentLevel) {
        String indent = "  ".repeat(indentLevel);
        sb.append(indent).append("- ").append(snapshot.getKey()).append("\n");

        for (DataSnapshot child : snapshot.getChildren()) {
            if (child.getValue() != null && !child.hasChildren()) {
                sb.append("  ").append(indent).append("- ").append(child.getKey()).append(": ").append(child.getValue().toString()).append("\n");
            } else {
                traverseSnapshot(child, sb, indentLevel + 1);
            }
        }
    }
}

3. Implement Firebase Notification Push (FCM) #

To send notifications to users, integrate Firebase Cloud Messaging:

3.1 Add FCM Dependency #

Add this to your module-level app/build.gradle:

dependencies {
    // Other dependencies...
    implementation 'com.google.firebase:firebase-messaging:23.4.1'
}

3.2 Create Messaging Service Class #

Create MyFirebaseMessagingService.java to handle incoming notifications:

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

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    private static final String CHANNEL_ID = "sensor_alert_channel";

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);
        if (remoteMessage.getNotification() != null) {
            sendNotification(remoteMessage.getNotification().getTitle(), remoteMessage.getNotification().getBody());
        }
    }

    // Show notification in system tray
    private void sendNotification(String title, String messageBody) {
        Intent intent = new Intent(this, RealtimeData.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_IMMUTABLE);

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, CHANNEL_ID)
                .setSmallIcon(R.drawable.ic_notification) // Replace with your icon
                .setContentTitle(title)
                .setContentText(messageBody)
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent)
                .setPriority(Notification.PRIORITY_DEFAULT);

        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        // Create channel for Android O and above
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel(CHANNEL_ID,
                    "Sensor Alerts",
                    NotificationManager.IMPORTANCE_DEFAULT);
            notificationManager.createNotificationChannel(channel);
        }

        notificationManager.notify(0, notificationBuilder.build());
    }
}

3.3 Register Service in Manifest #

Add this inside the <application> tag of your AndroidManifest.xml:

<service
    android:name=".MyFirebaseMessagingService"
    android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>

3.4 Trigger Notifications #

• Manual Trigger: Go to Firebase Console > Your Project > Cloud Messaging > Send your first message to send notifications manually.
• Auto Trigger on Abnormal Temp: Use Firebase Cloud Functions to listen for temperature changes. Example Node.js function:

const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp();

exports.sendTempAlert = functions.database.ref('/sensors/temp')
    .onUpdate((change) => {
        const newTemp = change.after.val();
        if (newTemp > 30) {
            const payload = {
                notification: {
                    title: "Temperature Alert!",
                    body: `Current temp is ${newTemp}°C - abnormal!`
                }
            };
            return admin.messaging().sendToTopic("sensor_users", payload);
        }
        return null;
    });

Key Notes #

• Ensure your Firebase project is correctly linked to Android Studio (google-services.json added).
• Add required permissions in AndroidManifest.xml:

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

• For testing, set Firebase database rules to public, then update to secure rules later.

内容的提问来源于stack exchange，提问作者Zack Choon