java - 通过服务进行震动检测

Question

我在创建抖动检测服务时遇到问题

后台服务

package com.likith.shakedetector;

import android.app.Service;
import android.content.Intent;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.IBinder;
import android.widget.Toast;

public class Background_service extends Service implements SensorEventListener
{
SensorManager sensorManager;
int count=0;

private float lastX = 0;
private float lastY = 0;
private float lastZ = 0;
private static final int MIN_FORCE = 10;
private static final int MIN_DIRECTION_CHANGE = 3;
private static final int MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE = 200;
private static final int MAX_TOTAL_DURATION_OF_SHAKE = 400;
private long mFirstDirectionChangeTime = 0;
private long mLastDirectionChangeTime;
private int mDirectionChangeCount = 0;

@Override   
public IBinder onBind(Intent intent) {
    return null;
}

public void onCreate()
{
    super.onCreate();
}

public void onDestroy() 
{
    super.onDestroy();
    sensorManager.unregisterListener(this);
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) 
{
    sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    sensorManager.registerListener(this,sensorManager
            .getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_UI);

    return START_STICKY;
}

public void onStart(Intent intent, int startId)
{
    sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    sensorManager.registerListener(this,sensorManager
            .getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_UI);
}

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

}

@SuppressWarnings("deprecation")
private void getAccelerometer(SensorEvent event) 
{
    //Toast.makeText(getApplicationContext(),"Shaked",Toast.LENGTH_LONG).show();

    float x = event.values[SensorManager.DATA_X];
    float y = event.values[SensorManager.DATA_Y];
    float z = event.values[SensorManager.DATA_Z];

    float totalMovement = Math.abs(x + y + z - lastX - lastY - lastZ);

    if (totalMovement <= MIN_FORCE) 
    {
        long now = System.currentTimeMillis();
        if (mFirstDirectionChangeTime == 0) 
        {
            mFirstDirectionChangeTime = now;
            mLastDirectionChangeTime = now;
        }

        long lastChangeWasAgo = now - mLastDirectionChangeTime;

        if (lastChangeWasAgo < MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE) 
        {
            mLastDirectionChangeTime = now;
            mDirectionChangeCount++;

            lastX = x;
            lastY = y;
            lastZ = z;

            if (mDirectionChangeCount >= MIN_DIRECTION_CHANGE) 
            {
                long totalDuration = now - mFirstDirectionChangeTime;
                if (totalDuration < MAX_TOTAL_DURATION_OF_SHAKE) 
                {
                    Toast.makeText(getApplicationContext(),"Shaked",Toast.LENGTH_LONG).show();
                    resetShakeParameters();
                }
            }

        }
        else 
        {
            resetShakeParameters();
        }
    }
}


public void onSensorChanged(SensorEvent event) 
{
    getAccelerometer(event);
}

protected void onResume() 
{
    sensorManager.registerListener(this,sensorManager
            .getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_UI);
}

protected void onPause()
{
    sensorManager.unregisterListener(this);
}

private void resetShakeParameters() 
{
    mFirstDirectionChangeTime = 0;
    mDirectionChangeCount = 0;
    mLastDirectionChangeTime = 0;
    lastX = 0;
    lastY = 0;
    lastZ = 0;
}

当我运行此服务时，它会连续打印 toast 消息。

如何更改代码，以便在我摇动设备时，它只打印一次 toast 消息？

Answer 1

你有

float totalMovement = Math.abs(x + y + z - lastX - lastY - lastZ);

您可能应该分别处理每个轴 - 因为每个轴的变化独立于其他轴。

float xMovement = Math.abs(x - lastX);
float yMovement = Math.abs(y - lastY);
float zMovement = Math.abs(z - lastZ);

if ((xMovement > MIN_FORCE) ||
    (yMovement > MIN_FORCE) ||
    (zMovement > MIN_FORCE)) {
     // motion detected
}

我在做类似的事情，发现最好先检查延迟 (MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE)。

Android API 18 有一个重要的运动传感器，如果存在于 Android 设备中可能对您的目的有效。

参见 http://developer.android.com/reference/android/hardware/Sensor.html#TYPE_SIGNIFICANT_MOTION