AppWidgetProvider显示电量

添加权限

 

<uses-permission android:name="android.permission.BATTERY_STATS"></uses-permission>

 

 

public class BatteryWidget extends AppWidgetProvider {

	public void onUpdate(Context context, AppWidgetManager appWidgetManager,
			int[] appWidgetIds) {
		super.onUpdate(context, appWidgetManager, appWidgetIds);
		Intent intent = new Intent(context, AppBatteryService.class);
		context.startService(intent);// 不是context.startActivity(intent);
	}

	/* UpdateService系统服务后台运行 */
	public static class AppBatteryService extends Service {//不要忘记static 否则会抛出Unable to instantiate service异常
		private UpdateReceiver receiver;

		public IBinder onBind(Intent arg0) {
			return null;
		}

		public void onStart(Intent intent, int startId) {
			super.onStart(intent, startId);

			IntentFilter filter = new IntentFilter(
					Intent.ACTION_BATTERY_CHANGED);
			receiver = new UpdateReceiver();
			registerReceiver(receiver, filter);

			RemoteViews updateViews = getRemoteViews(this);
			/* 建立ComponentName对象与AppWidgetManager对象 */
			ComponentName thisWidget = new ComponentName(this,
					BatteryWidget.class);
			AppWidgetManager manager = AppWidgetManager.getInstance(this);
			manager.updateAppWidget(thisWidget, updateViews);
		}

		public void onDestroy() {
			unregisterReceiver(receiver);
			super.onDestroy();
		}

		public RemoteViews getRemoteViews(Context context) {
			RemoteViews retRemoteViews = null;
			retRemoteViews = new RemoteViews(context.getPackageName(),
					R.layout.update_widget);
			/* 取得保存在SharedPreferences的电量值 */
			int power = 0;
			SharedPreferences pres = context.getSharedPreferences("battery",
					Context.MODE_PRIVATE);
			if (pres != null) {
				power = pres.getInt("power", 0);
			}
			/* 更新电量文字显示 */
			retRemoteViews.setTextViewText(R.id.myTextView1, power + "%");
			/* 更新电量图形显示 */
			if (power != 0) {
				Bitmap bmp = BitmapFactory.decodeResource(
						context.getResources(), R.drawable.power);

				float x = 57.0f / 100 * power;
				Matrix matrix = new Matrix();
				matrix.postScale(x, 1.0f);
				Bitmap resizeBmp = Bitmap.createBitmap(bmp, 0, 0, 1, 39,
						matrix, true);

				retRemoteViews.setBitmap(R.id.myImageView1,

				"setImageBitmap", resizeBmp);
			}
			return retRemoteViews;
		}

		public class UpdateReceiver extends BroadcastReceiver {

			public void onReceive(Context context, Intent intent) {

				if (intent.getAction().equals

				(Intent.ACTION_BATTERY_CHANGED)) {

					int intLevel = intent.getIntExtra("level", 0);
					int intScale = intent.getIntExtra("scale", 100);
					/* 将电量保存在SharedPreferences中 */
					SharedPreferences pres =

					context.getSharedPreferences("battery",
							Context.MODE_PRIVATE);
					if (pres != null) {
						SharedPreferences.Editor ed = pres.edit();
						ed.putInt("power", (intLevel * 100 /

						intScale));
						ed.commit();
					}
				}
			}

		}
	}

}

 manifest.xml

 

<receiver
			android:name=".BatteryWidget"
			android:label="@string/app_name">
			<intent-filter>
				<action
					android:name="android.appwidget.action.APPWIDGET_UPDATE" />
			</intent-filter>
			<meta-data
				android:name="android.appwidget.provider"
				android:resource="@xml/widget_template" />
		</receiver>
		<service
			android:name=".BatteryWidget$AppBatteryService" />

 widget_template.xml

 

<?xml version="1.0" encoding="utf-8"?> 
<appwidget-provider
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:minWidth="72dip" 
  android:minHeight="72dip" 
  android:updatePeriodMillis="10000" 
  android:initialLayout="@layout/update_widget" 
/>

 update_widget.xml

 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:background="@drawable/batt"
	android:orientation="vertical"
	android:layout_width="72dip"
	android:layout_height="72dip">
	<ImageView
		android:id="@+id/myImageView1"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:layout_gravity="center"
		android:layout_marginLeft="5dip"
		android:layout_marginTop="6dip" />
	<TextView
		android:id="@+id/myTextView1"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:layout_x="24px"
		android:layout_y="22px"
		android:layout_marginTop="44dip"
		android:gravity="center_horizontal" />
</RelativeLayout>

power.png  
 
batt.png