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

public class MainActivity extends Activity implements SensorEventListener {
    public static final String TAG = "SensorTest";
    //调用距离传感器，控制屏幕
    private SensorManager mManager;//传感器管理对象
    //屏幕开关
    private PowerManager localPowerManager = null;//电源管理对象
    private PowerManager.WakeLock localWakeLock = null;//电源锁
    //TextView
    private TextView tv;//基本上没啥用
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        tv = (TextView) findViewById(R.id.tv);

        mManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);
        //获取系统服务POWER_SERVICE，返回一个PowerManager对象
        localPowerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
        //获取PowerManager.WakeLock对象,后面的参数|表示同时传入两个值,最后的是LogCat里用的Tag 
        localWakeLock = this.localPowerManager.newWakeLock(32, "MyPower");//第一个参数为电源锁级别，第二个是日志tag
    }

    public void onResume(){
        super.onResume();
        mManager.registerListener(this, mManager.getDefaultSensor(Sensor.TYPE_PROXIMITY),// 距离感应器
                SensorManager.SENSOR_DELAY_NORMAL);//注册传感器，第一个参数为距离监听器，第二个是传感器类型，第三个是延迟类型
    }

    public void onStop(){
        super.onStop();
        Log.d(TAG,"on stop");
    }

    public void onDestroy(){
        super.onDestroy();
        Log.d(TAG,"on destroy");
        if(mManager != null){
            localWakeLock.release();//释放电源锁，如果不释放finish这个acitivity后仍然会有自动锁屏的效果，不信可以试一试
            mManager.unregisterListener(this);//注销传感器监听
        }
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        float[] its = event.values;
        //Log.d(TAG,"its array:"+its+"sensor type :"+event.sensor.getType()+" proximity type:"+Sensor.TYPE_PROXIMITY);
        if (its != null && event.sensor.getType() == Sensor.TYPE_PROXIMITY) {

            System.out.println("its[0]:" + its[0]);
            tv.setText(its[0]+"");
            //经过测试，当手贴近距离感应器的时候its[0]返回值为0.0，当手离开时返回1.0
            if (its[0] == 0.0) {// 贴近手机

                System.out.println("hands up");
                Log.d(TAG,"hands up in calling activity");
                if (localWakeLock.isHeld()) {
                    return;
                } else{

                    localWakeLock.acquire();// 申请设备电源锁
                }
            } else {// 远离手机

                System.out.println("hands moved");
                Log.d(TAG,"hands moved in calling activity");
                if (localWakeLock.isHeld()) {
                    return;
                } else{
                    localWakeLock.setReferenceCounted(false);
                    localWakeLock.release(); // 释放设备电源锁
                }
            }
        }

    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO 自动生成的方法存根

    }


}