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基于Android的计步器(Pedometer)的讲解(四)——后台记步
2015-01-07 10:37:05         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:

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:
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:
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;
		}
		
	}

}
这些是主要的代码,其他次要的我就不贴出来了,如果想要demo的朋友可以在下面留言,我给你们。

如果大家有什么建议,可以提出来哦。

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相关TAG标签 计步器 后台
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