Android开发笔记（一百一十七）app省电方略

import java.lang.reflect.Field;
import java.lang.reflect.Method;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.IBinder;
import android.os.PowerManager;
import android.os.SystemClock;
import android.util.Log;

//注意，PowerManager只有系统应用才能操作，普通应用不能操作，所以下面代码仅供参考
public class PowerUtil {
	
	private final static String TAG = "PowerUtil";
	
	private static int getValue(Context ctx, String methodName, int defValue) {
		int value = defValue;
		PowerManager pm = (PowerManager) ctx.getSystemService(Context.POWER_SERVICE);
		try {
			Class<?> pmClass = Class.forName(pm.getClass().getName());
			Field field = pmClass.getDeclaredField("mService");
			field.setAccessible(true);
			Object iPM = field.get(pm);
			Class<?> iPMClass = Class.forName(iPM.getClass().getName());
			Method method = iPMClass.getDeclaredMethod(methodName);
			method.setAccessible(true);
			value = (Integer) method.invoke(iPM);
		} catch (Exception e) {
			e.printStackTrace();
		}
		Log.d(TAG, "methodName="+methodName+", value="+value);
		return value;
	}

	public static int getMinLight(Context ctx) {
		return getValue(ctx, "getMinimumScreenBrightnessSetting", 0);
	}

	public static int getMaxLight(Context ctx) {
		return getValue(ctx, "getMaximumScreenBrightnessSetting", 255);
	}

	public static int getDefLight(Context ctx) {
		return getValue(ctx, "getDefaultScreenBrightnessSetting", 100);
	}
	
    //设置屏幕亮度。light取值0-255
    public static void setLight(Context ctx, int light) {
		PowerManager pm = (PowerManager) ctx.getSystemService(Context.POWER_SERVICE);
        try {
            Class<?> pmClass = Class.forName(pm.getClass().getName());
            // 得到PowerManager类中的成员mService（mService为PowerManagerService类型）
            Field field = pmClass.getDeclaredField("mService");
            field.setAccessible(true);
            // 实例化mService
            Object iPM = field.get(pm);
            // 得到PowerManagerService对应的Class对象
            Class<?> iPMClass = Class.forName(iPM.getClass().getName());
            /*
             * 得到PowerManagerService的函数setBacklightBrightness对应的Method对象，
             * PowerManager的函数setBacklightBrightness实现在PowerManagerService中
             */
            Method method = iPMClass.getDeclaredMethod("setBacklightBrightness", int.class);
            method.setAccessible(true);
            // 调用实现PowerManagerService的setBacklightBrightness
            method.invoke(iPM, light);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    public static void resetLight(Context ctx, int light) {
        try {
            Object power;
            Class <?> ServiceManager = Class.forName("android.os.ServiceManager");
            Class <?> Stub = Class.forName("android.os.IPowerManager$Stub");

            Method getService = ServiceManager.getMethod("getService", new Class[] {String.class});
            //Method asInterface = GetStub.getMethod("asInterface", new Class[] {IBinder.class});//of this class?
            Method asInterface = Stub.getMethod("asInterface", new Class[] {IBinder.class});    //of this class?
            IBinder iBinder = (IBinder) getService.invoke(null, new Object[] {Context.POWER_SERVICE});//
            power = asInterface.invoke(null,iBinder);//or call constructor Stub?//

            Method setBacklightBrightness = power.getClass().getMethod("setBacklightBrightness", new Class[]{int.class}); 
            setBacklightBrightness.invoke(power, new Object[]{light});
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    //锁屏
    public static void lockScreen(Context ctx) {
		PowerManager pm = (PowerManager) ctx.getSystemService(Context.POWER_SERVICE);
        pm.goToSleep(SystemClock.uptimeMillis());
    }

    //解锁
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
	public static void unLockScreen(Context ctx) {
		PowerManager pm = (PowerManager) ctx.getSystemService(Context.POWER_SERVICE);
        pm.wakeUp(SystemClock.uptimeMillis());
    }

    //重启
    public static void reboot(Context ctx) {
		PowerManager pm = (PowerManager) ctx.getSystemService(Context.POWER_SERVICE);
        pm.reboot(null);
    }

    //关机
    public static void shutDown(Context ctx) {
        Intent intent = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN");
        intent.putExtra("android.intent.extra.KEY_CONFIRM", false);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        // 弹出系统内置的对话框，选择确定关机或取消关机
        ctx.startActivity(intent);
    }
    
}

import com.example.exmbattery.util.DateUtils;

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 BatteryActivity extends Activity {

	private TextView tv_battery_change;
	private static TextView tv_power_status;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_battery);

		tv_battery_change = (TextView) findViewById(R.id.tv_battery_change);
		tv_power_status = (TextView) findViewById(R.id.tv_power_status);
	}
	
	@Override
	protected void onStart() {
		super.onStart();
		batteryChangeReceiver = new BatteryChangeReceiver();
		IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
		registerReceiver(batteryChangeReceiver, filter);
	}
	
	@Override
	protected void onStop() {
		super.onStop();
		unregisterReceiver(batteryChangeReceiver);
	}

    private BatteryChangeReceiver batteryChangeReceiver;
    private class BatteryChangeReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent != null) {
            	int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
            	int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
            	int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, 0);
            	int healthy = intent.getIntExtra(BatteryManager.EXTRA_HEALTH, 0);
            	int voltage = intent.getIntExtra(BatteryManager.EXTRA_VOLTAGE, 0);
            	int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 3);
            	String technology = intent.getStringExtra(BatteryManager.EXTRA_TECHNOLOGY);
            	int temperature = intent.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0);
            	boolean present = intent.getBooleanExtra(BatteryManager.EXTRA_PRESENT, false);

            	String desc = String.format("%s : 收到广播：%s",
            			DateUtils.getNowDateTime(), intent.getAction());
            	desc = String.format("%s\n电量刻度=%d", desc, scale);
            	desc = String.format("%s\n当前电量=%d", desc, level);
            	desc = String.format("%s\n当前状态=%s", desc, mStatus[status]);
            	desc = String.format("%s\n健康程度=%s", desc, mHealthy[healthy]);
            	desc = String.format("%s\n当前电压=%d", desc, voltage);
            	desc = String.format("%s\n当前电源=%s", desc, mPlugged[plugged]);
            	desc = String.format("%s\n当前技术=%s", desc, technology);
            	desc = String.format("%s\n当前温度=%d", desc, temperature/10);
            	desc = String.format("%s\n是否提供电池=%s", desc, present?"是":"否");
            	tv_battery_change.setText(desc);
            }
        }
    }
    
    private static String[] mStatus = {"不存在", "未知", "正在充电", "正在断电", "不在充电", "充满"};
    private static String[] mHealthy = {"不存在", "未知", "良好", "过热", "坏了", "短路", "未知错误", "冷却"};
    private static String[] mPlugged = {"电池", "充电器", "USB", "不存在", "无线"};

    private static String mChange = ""; 
    public static class PowerChangeReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent != null) {
            	mChange = String.format("%s\n%s : 收到广播：%s", 
            			mChange, DateUtils.getNowDateTime(), intent.getAction());
            	tv_power_status.setText(mChange);
            }
        }
    }
}

import com.example.exmbattery.util.DateUtils;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;

public class LockScreenReceiver extends BroadcastReceiver {

	private static final String TAG = "LockScreenReceiver";

	@Override
	public void onReceive(Context context, Intent intent) {
		if (intent != null) {
			String mChange = "";
			mChange = String.format("%s\n%s : 收到广播：%s", mChange,
					DateUtils.getNowDateTime(), intent.getAction());
			if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
				mChange = String.format("%s\n这是屏幕点亮事件", mChange);
			} else if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
				mChange = String.format("%s\n这是屏幕关闭事件", mChange);
			} else if (intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
				mChange = String.format("%s\n这是用户解锁事件", mChange);
			}
			Log.d(TAG, mChange);
			MainApplication.getInstance().setChangeDesc(mChange);
		}
	}

}

import android.app.Application;
import android.content.Intent;
import android.content.IntentFilter;

public class MainApplication extends Application {

	private static MainApplication mApp;
	private LockScreenReceiver mReceiver;
	private String mChange = "";

	public static MainApplication getInstance() {
		return mApp;
	}

	public String getChangeDesc() {
		return mApp.mChange;
	}

	public void setChangeDesc(String change) {
		mApp.mChange = mApp.mChange + change;
	}

	@Override
	public void onCreate() {
		super.onCreate();
		mApp = this;
		mReceiver = new LockScreenReceiver();
		IntentFilter filter = new IntentFilter();
		filter.addAction(Intent.ACTION_SCREEN_ON);
		filter.addAction(Intent.ACTION_SCREEN_OFF);
		filter.addAction(Intent.ACTION_USER_PRESENT);
		registerReceiver(mReceiver, filter);
	}
	
	@Override
	public void onTerminate() {
		unregisterReceiver(mReceiver);
		super.onTerminate();
	}
	
}

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class ScreenActivity extends Activity {

	private static TextView tv_screen;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_screen);
		tv_screen = (TextView) findViewById(R.id.tv_screen);
	}

	@Override
	protected void onStart() {
		super.onStart();
		tv_screen.setText(MainApplication.getInstance().getChangeDesc());
	}

}