[Android] 取得Device目前電池電量

(How to get current battery level)

Android系統會在電池狀態發生變化時，發出System broadcast intent，會附帶電池狀態、電量、溫度等內容，APP要取得電池電量就必須註冊BroadcastReceiver來接收此intent。


程式碼說明

一、建立BroadcastReceiver物件，實作其onReceive()方法

private BroadcastReceiver batteryInfoReceiver = new BroadcastReceiver(){
@Override
 public void onReceive(Context context, Intent intent) {
 int lv=intent.getIntExtra("level",0);
 batteryLevelTxt.setText(String.valueOf(lv)+"%");
 }  
};

二、註冊BroadcastReceiver，filter設定為ACTION_BATTERY_CHANGED，它將會在電池狀態改變時觸發其onReceive方法

package com.batteryDemo;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Bundle;
import android.widget.TextView;

public class BatteryDemoActivity extends Activity {
    
private TextView batteryLevelTxt;
 
private BroadcastReceiver batteryInfoReceiver = new BroadcastReceiver(){
@Override
public void onReceive(Context context,Intent intent){
 int lv=intent.getIntExtra("level",0);
 batteryLevelTxt.setText(String.valueOf(lv)+"%");
 }  
};
 
@Override
public void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
        
 batteryLevelTxt=(TextView)findViewById(R.id.LevelTxt);

 this.registerReceiver(batteryInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
}
}