Home Screen Battery Widget

It's a simple Battery Widget, with battery level and charging status displayed on Android Home Screen.



Create a layout file of our widget, simple with a TextView only - /res/layout/androidbatterywidget_layout.xml.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
>
<TextView
 android:id="@+id/level"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
   android:gravity="center"
   android:textColor="#000000"
/>
</LinearLayout>

The provider info, /res/xml/androidbatterywidgetproviderinfo.xml.

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
 android:minWidth="146dp"
 android:minHeight="72dp"
 android:initialLayout="@layout/androidbatterywidget_layout"
 >
</appwidget-provider>

Implement AndroidBatteryWidgetProvider.java, it's our AppWidgetProvider.
It show "waiting" initially, and start our Service in onUpdate() method.

package com.exercise.AndroidBatteryWidget;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.widget.RemoteViews;

public class AndroidBatteryWidgetProvider extends AppWidgetProvider {

 
 @Override
 public void onUpdate(Context context, AppWidgetManager appWidgetManager,
   int[] appWidgetIds) {
  // TODO Auto-generated method stub
  updateWidget(context);
  context.startService(new Intent(context, MyBatteryReceiver.class));
 }

 public void updateWidget(Context context){
  RemoteViews updateViews = new RemoteViews(context.getPackageName(), R.layout.androidbatterywidget_layout);
    updateViews.setTextViewText(R.id.level, "waiting!");
   
    ComponentName myComponentName = new ComponentName(context, AndroidBatteryWidgetProvider.class);
    AppWidgetManager manager = AppWidgetManager.getInstance(context);
    manager.updateAppWidget(myComponentName, updateViews);
 }

}

Implement MyBatteryReceiver.java.
In onCreate(), it register the BroadcastReceiver, myReceiver, to receive the event of Intent.ACTION_BATTERY_CHANGED. And also update widget in myReceiver.onReceive().

package com.exercise.AndroidBatteryWidget;

import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.IBinder;
import android.widget.RemoteViews;

public class MyBatteryReceiver extends Service {
 
 private int batterylevel = 0;
 private String batteryStatus ="";

   private BroadcastReceiver myReceiver = new BroadcastReceiver()
   {
       @Override
       public void onReceive(Context context, Intent intent)
       {
        String action = intent.getAction();
        if (action.equals(Intent.ACTION_BATTERY_CHANGED))
        {
         batterylevel = intent.getIntExtra("level", 0);
         
         int status = intent.getIntExtra("status", BatteryManager.BATTERY_STATUS_UNKNOWN);
         String strStatus;
         if (status == BatteryManager.BATTERY_STATUS_CHARGING){
          batteryStatus = "Charging"; 
         } else if (status == BatteryManager.BATTERY_STATUS_DISCHARGING){
          batteryStatus = "Dis-charging";
         } else if (status == BatteryManager.BATTERY_STATUS_NOT_CHARGING){
          batteryStatus = "Not charging";
         } else if (status == BatteryManager.BATTERY_STATUS_FULL){
          batteryStatus = "Full";
         } else {
          batteryStatus = "";
         }
         
         updateAppWidget(context);
        }
       }
      
       public void updateAppWidget(Context context){
        RemoteViews updateViews = new RemoteViews(context.getPackageName(), R.layout.androidbatterywidget_layout);
        updateViews.setTextViewText(R.id.level,
          "Bat. Status:\n" +
          "Level: " + batterylevel + "%\n" +
          "Status: " + batteryStatus);
       
        ComponentName myComponentName = new ComponentName(context, AndroidBatteryWidgetProvider.class);
        AppWidgetManager manager = AppWidgetManager.getInstance(context);
        manager.updateAppWidget(myComponentName, updateViews);
      }
   };
 
 @Override
 public IBinder onBind(Intent arg0) {
  // TODO Auto-generated method stub
  return null;
 }

 @Override
 public void onCreate() {
  // TODO Auto-generated method stub
  super.onCreate();
  
  IntentFilter intentFilter = new IntentFilter();
  intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
  registerReceiver(myReceiver, intentFilter);
 }

 @Override
 public void onDestroy() {
  // TODO Auto-generated method stub
  super.onDestroy();
  unregisterReceiver(myReceiver);
 }

}

Modify AndroidManifest.xml to include receiver and server in our application.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.exercise.AndroidBatteryWidget"
     android:versionCode="1"
     android:versionName="1.0">
   <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true">
    <receiver android:name=".AndroidBatteryWidgetProvider" >
     <intent-filter>
      <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
     </intent-filter>
     <meta-data android:name="android.appwidget.provider"
      android:resource="@xml/androidbatterywidgetproviderinfo" />
    </receiver>

    <service android:name=".MyBatteryReceiver" android:label="MyBatteryReceiver">
     <intent-filter>
      <action android:name="android.intent.action.BATTERY_CHANGED" />
     </intent-filter>
    </service>
 
   </application>
   <uses-sdk android:minSdkVersion="4" />
</manifest>

Download the files.

Related Article:
- A simple Home Screen App Widget to get Date/Time.
- android.app.Service
- Detect Battery Info.