Android对手机口袋状态的检测，距离传感器

通常手机自带的距离传感器只能检测到几厘米的范围，一般用于判断手机在不在口袋中

import Android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.Log;

public class ProximitySensor implements SensorEventListener {

private static final String TAG = "ProximitySensor";
    private static ProximitySensor instance;

private SensorManager mSensorManager;
    private float distance = -1;
    private boolean mHasStarted = false;

private ProximitySensor() {
    }

public static ProximitySensor getInstance() {
        if (instance == null) {
            instance = new ProximitySensor();
        }
        return instance;
    }

/**
    * 启动距离传感器
    */
    public static void start(Context context) {
        ProximitySensor.getInstance().registerListener(context);
    }

/**
    * 停止距离传感器
    */
    public static void stop() {
        ProximitySensor.getInstance().unregisterListener();
    }

/**
    * 获取手机距离（单位厘米）
    */
    public static float getDistance() {
        return ProximitySensor.getInstance().getValue();
    }

    // ------------------------------------------------------------------------------

/**
    * Use this method to start listening of the sensor
    */
    private void registerListener(Context context) {
        if (mHasStarted) {
            return;
        }
        mHasStarted = true;
        mSensorManager = (SensorManager) context.getApplicationContext().getSystemService(Context.SENSOR_SERVICE);
        Sensor proximitySensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY); // 获取距离传感器
        if (proximitySensor != null) { // 距离传感器存在时才执行
            mSensorManager.registerListener(this, proximitySensor, SensorManager.SENSOR_DELAY_NORMAL); // 注册事件监听
        }
    }

/**
    * Use this method to stop listening of the sensor
    */
    private void unregisterListener() {
        if (!mHasStarted || mSensorManager == null) {
            return;
        }
        mHasStarted = false;
        mSensorManager.unregisterListener(this);
    }

private float getValue() {
        if (!mHasStarted) {
            Log.w(TAG, "proximity sensor has not start!");
        }
        return distance;
    }

@Override
    public void onSensorChanged(SensorEvent event) {
        if (event != null && event.sensor.getType() == Sensor.TYPE_PROXIMITY) {
            // values[0]: Proximity sensor distance measured in centimeters
            distance = event.values[0];
            Log.v(TAG, "proximity sensor distance: " + distance);
        }
    }

@Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }