android顯示手機電量

package com.basillee.asus.demo;

import android.app.Notification;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity11 extends ActionBarActivity {

    private TextView textViewLevel=null;
    private int batteryLevel;
    private int batteryScale;
    private Button buttonBatteryShow;
    private BroadcastReceiver broadcastReceiver=new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            //獲取當前電量，如未獲取具體數值，則默認爲0
            batteryLevel=intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
            //獲取最大電量，如未獲取到具體數值，則默認爲100
            batteryScale=intent.getIntExtra(BatteryManager.EXTRA_SCALE,100);
            //顯示電量
            textViewLevel.setText("電量"+(batteryLevel*100/batteryScale)+"%");
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_activity11);
        textViewLevel= (TextView) findViewById(R.id.textViewBattery);
        buttonBatteryShow= (Button) findViewById(R.id.button_show_battery);
        buttonBatteryShow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                IntentFilter intentFilter=new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
                //註冊接收器以獲取電量信息
                registerReceiver(broadcastReceiver, intentFilter);
            }
        });
    }

}

http://jingyan.baidu.com/season/48891