基于Android的计步器(Pedometer)的讲解(四)——后台记步
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基于Android的计步器(Pedometer)的讲解(四)——后台记步
andyhe91 发表于2年前
基于Android的计步器(Pedometer)的讲解(四)——后台记步
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摘要: 基于Android的计步器(Pedometer)的讲解(四)——后台记步
  • 基于Android的计步器(Pedometer)的讲解(四)——后台记步

  • 2015-01-07      58 个评论    来源:a296777513的专栏   

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  • 今天先不说Pedometer(计步器)项目UI方面的了,今天讲一个基于重力加速度的记步功能传感器(Sensor),然后

    在后台开启记步。

     

    计步器(Pedometer)整个项目的源代码,感兴趣的朋友可以下载来看看(记得帮小弟在github打个星~)

     

    先上几张效果图:(效果和上一篇讲到的CircleBar非常的相似,因为记步功能在后台)

    \\

    如图所示,能根据你的一些基本参数,来记步。有一个缺点,因为这个是根据感应加速度来计算是否走一步,所以你在原地晃手机,也会记步,不过正常的走路还是挺准确的。

    首先给出StepDetector类的代码:

     

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    package com.example.histogram.widet;
     
    import android.content.Context;
    import android.hardware.Sensor;
    import android.hardware.SensorEvent;
    import android.hardware.SensorEventListener;
    import android.hardware.SensorManager;
     
    /**
      * 这是一个实现了信号监听的记步的类
      * 这是从谷歌找来的一个记步的算法,看不太懂
      * @author Liyachao Date:2015-1-6
      *
      */
    public class StepDetector implements SensorEventListener {
     
         public static int CURRENT_SETP = 0 ;
         public static float SENSITIVITY = 10 ; // SENSITIVITY灵敏度
         private float mLastValues[] = new float [ 3 * 2 ];
         private float mScale[] = new float [ 2 ];
         private float mYOffset;
         private static long end = 0 ;
         private static long start = 0 ;
         /**
          * 最后加速度方向
          */
         private float mLastDirections[] = new float [ 3 * 2 ];
         private float mLastExtremes[][] = { new float [ 3 * 2 ], new float [ 3 * 2 ] };
         private float mLastDiff[] = new float [ 3 * 2 ];
         private int mLastMatch = - 1 ;
     
         /**
          * 传入上下文的构造函数
          *
          * @param context
          */
         public StepDetector(Context context) {
             super ();
             int h = 480 ;
             mYOffset = h * 0 .5f;
             mScale[ 0 ] = -(h * 0 .5f * ( 1 .0f / (SensorManager.STANDARD_GRAVITY * 2 )));
             mScale[ 1 ] = -(h * 0 .5f * ( 1 .0f / (SensorManager.MAGNETIC_FIELD_EARTH_MAX)));
         }
     
         //当传感器检测到的数值发生变化时就会调用这个方法
         public void onSensorChanged(SensorEvent event) {
             Sensor sensor = event.sensor;
             synchronized ( this ) {
                 if (sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
     
                     float vSum = 0 ;
                     for ( int i = 0 ; i < 3 ; i++) {
                         final float v = mYOffset + event.values[i] * mScale[ 1 ];
                         vSum += v;
                     }
                     int k = 0 ;
                     float v = vSum / 3 ;
     
                     float direction = (v > mLastValues[k] ? 1
                             : (v < mLastValues[k] ? - 1 : 0 ));
                     if (direction == -mLastDirections[k]) {
                         // Direction changed
                         int extType = (direction > 0 ? 0 : 1 ); // minumum or
                                                                 // maximum?
                         mLastExtremes[extType][k] = mLastValues[k];
                         float diff = Math.abs(mLastExtremes[extType][k]
                                 - mLastExtremes[ 1 - extType][k]);
     
                         if (diff > SENSITIVITY) {
                             boolean isAlmostAsLargeAsPrevious = diff > (mLastDiff[k] * 2 / 3 );
                             boolean isPreviousLargeEnough = mLastDiff[k] > (diff / 3 );
                             boolean isNotContra = (mLastMatch != 1 - extType);
     
                             if (isAlmostAsLargeAsPrevious && isPreviousLargeEnough
                                     && isNotContra) {
                                 end = System.currentTimeMillis();
                                 if (end - start > 500 ) { // 此时判断为走了一步
     
                                     CURRENT_SETP++;
                                     mLastMatch = extType;
                                     start = end;
                                 }
                             } else {
                                 mLastMatch = - 1 ;
                             }
                         }
                         mLastDiff[k] = diff;
                     }
                     mLastDirections[k] = direction;
                     mLastValues[k] = v;
                 }
     
             }
         }
         //当传感器的经度发生变化时就会调用这个方法,在这里没有用
         public void onAccuracyChanged(Sensor arg0, int arg1) {
     
         }
     
    }


    下来是后台服务StepService的代码:

     

     

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    package com.example.histogram.widet;
     
    import android.app.Service;
    import android.content.Context;
    import android.content.Intent;
    import android.hardware.Sensor;
    import android.hardware.SensorManager;
    import android.os.IBinder;
     
    public class StepService extends Service {
         public static Boolean flag = false ;
         private SensorManager sensorManager;
         private StepDetector stepDetector;
     
         @Override
         public IBinder onBind(Intent arg0) {
             // TODO Auto-generated method stub
             return null ;
         }
     
         @Override
         public void onCreate() {
             super .onCreate();
             //这里开启了一个线程,因为后台服务也是在主线程中进行,这样可以安全点,防止主线程阻塞
             new Thread( new Runnable() {
                 public void run() {
                     startStepDetector();
                 }
             }).start();
     
         }
     
         private void startStepDetector() {
             flag = true ;
             stepDetector = new StepDetector( this );
             sensorManager = (SensorManager) this .getSystemService(SENSOR_SERVICE); //获取传感器管理器的实例
             Sensor sensor = sensorManager
                     .getDefaultSensor(Sensor.TYPE_ACCELEROMETER); //获得传感器的类型,这里获得的类型是加速度传感器
             //此方法用来注册,只有注册过才会生效,参数:SensorEventListener的实例,Sensor的实例,更新速率
             sensorManager.registerListener(stepDetector, sensor,
                     SensorManager.SENSOR_DELAY_FASTEST);
         }
     
         @Override
         public int onStartCommand(Intent intent, int flags, int startId) {
             return super .onStartCommand(intent, flags, startId);
         }
     
         @Override
         public void onDestroy() {
             super .onDestroy();
             flag = false ;
             if (stepDetector != null ) {
                 sensorManager.unregisterListener(stepDetector);
             }
     
         }
    }


    最后把FragmentPedometer测试页面的代码也给大家,如果大家看过之前的博客,应该知道这是一个碎片。如果没看过,看兴趣的朋友可以看看之前的博文:

     

     

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    package com.example.histogram;
     
    import java.text.SimpleDateFormat;
    import java.util.Date;
     
     
     
     
     
     
    import com.example.changepage1.R;
    import com.example.histogram.widet.CircleBar;
    import com.example.histogram.widet.StepDetector;
    import com.example.histogram.widet.StepService;
    import com.example.histogram.widet.Weather;
     
     
     
    import android.annotation.SuppressLint;
    import android.content.Intent;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.view.View.OnClickListener;
     
    /**
      * 这是记步的碎片
      * Author: 李垭超   email:296777513@qq.com
      * Date: 2015-1-6
      * Time: 下午8:39
      */
    public class FragmentPedometer extends Fragment implements OnClickListener{
         private View view;
         private CircleBar circleBar;
         private int total_step = 0 ;
         private Thread thread;
         private int Type = 1 ;
         private int calories = 0 ;
         private int step_length = 50 ;
         private int weight = 70 ;
         private Weather weather;
         private String test;
         private boolean flag = true ; // 来判断第三个页面是否开启动画
     
         @SuppressLint (HandlerLeak)
         Handler handler = new Handler() {
             public void handleMessage(Message msg) {
                 super .handleMessage(msg);
                 total_step = StepDetector.CURRENT_SETP;
                 if (Type == 1 ) {
                     circleBar.setProgress(total_step, Type);
                 } else if (Type == 2 ) {
                     calories = ( int ) (weight * total_step * step_length * 0.01 * 0.01 );
                     circleBar.setProgress(calories, Type);
                 } else if (Type == 3 ) {
                     if (flag) {
                         circleBar.startCustomAnimation();
                         flag = false ;
                     }
                     if (test != null || weather.getWeather() == null ) {
                         weather.setWeather(正在更新中...);
                         weather.setPtime();
                         weather.setTemp1();
                         weather.setTemp2();
                         circleBar.startCustomAnimation();
                         circleBar.setWeather(weather);
                     } else {
                         circleBar.setWeather(weather);
                     }
     
                 }
     
             }
     
         };
     
     
         @Override
         public View onCreateView(LayoutInflater inflater, ViewGroup container,
                 Bundle savedInstanceState) {
             view = inflater.inflate(R.layout.pedometer, container, false );
             init();
             mThread();
             return view;
         }
         private void init() {      
             Intent intent = new Intent(getActivity(), StepService. class );
             getActivity().startService(intent);
             weather = new Weather();
             circleBar = (CircleBar) view.findViewById(R.id.progress_pedometer);
             circleBar.setMax( 10000 );
             circleBar.setProgress(StepDetector.CURRENT_SETP, 1 );
             circleBar.startCustomAnimation();
             circleBar.setOnClickListener( this );
     
         }
         
         private void mThread() {
             if (thread == null ) {
     
                 thread = new Thread( new Runnable() {
                     public void run() {
                         while ( true ) {
                             try {
                                 Thread.sleep( 500 );
                             } catch (InterruptedException e) {
                                 e.printStackTrace();
                             }
                             if (StepService.flag) {
                                 Message msg = new Message();
                                 handler.sendMessage(msg);
                             }
                         }
                     }
                 });
                 thread.start();
             }
         }
         @Override
         public void onClick(View v) {
             switch (v.getId()) {
             case R.id.progress_pedometer:
                 if (Type == 1 ) {
                     Type = 2 ;
                 } else if (Type == 2 ) {
                     flag = true ;
                     Type = 3 ;
                 } else if (Type == 3 ) {
                     Type = 1 ;
                 }
                 Message msg = new Message();
                 handler.sendMessage(msg);
                 break ;
             default :
                 break ;
             }
             
         }
     
    }


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    orangebook
    嗯!不错,就是计步关键代码能,算法分析出来就好了
    ×
    andyhe91
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