今天先不說Pedometer（計步器）項目UI方面的了，今天講一個基于重力加快度的記步功能傳感器（Sensor），然后
在后臺開啟記步。

計步器（Pedometer）全部項目標(biāo)源代碼，感興趣的同伙可以下載來看看(記得幫小弟在github打個星~)
https://github.com/296777513/pedometer
先上幾張效不雅圖：（效不雅和上一篇講到的CircleBar異常的相似，因為記步功能在后臺）
[img]http://img.blog.csdn.net/20150106203148421?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvYTI5Njc3NzUxMw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center[img]http://img.blog.csdn.net/20150106203225891?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvYTI5Njc3NzUxMw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center

如圖所示，能根據(jù)你的一些根本參數(shù)，來記步。有一個缺點，因為這個是根據(jù)感應(yīng)加快度來計算是否走一步，所以你在原地晃手機，也會記步，不過正常的走路照樣挺精確的。
起首給出StepDetector類的代碼：

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;

/**
 * 這是一個實現(xiàn)了旌旗燈號監(jiān)聽的記步的類
 * 這是大年夜谷歌找來的一個記步的算法，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靈敏度
	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;
	/**
	 * 最后加快度偏向
	 */
	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;

	/**
	 * 傳入高低文的構(gòu)造函數(shù)
	 * 
	 * @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)));
	}

	//當(dāng)傳感器檢測到的數(shù)值產(chǎn)生變更時就會調(diào)用這個辦法
	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) {// 此時斷定為走了一步

								CURRENT_SETP++;
								mLastMatch = extType;
								start = end;
							}
						} else {
							mLastMatch = -1;
						}
					}
					mLastDiff[k] = diff;
				}
				mLastDirections[k] = direction;
				mLastValues[k] = v;
			}

		}
	}
	//當(dāng)傳感器的經(jīng)度產(chǎn)生變更時就會調(diào)用這個辦法，在這瑯綾腔有效
	public void onAccuracyChanged(Sensor arg0, int arg1) {

	}

}

下來是后臺辦事StepService的代碼：

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();
		//這里開啟了一個線程，因為后臺辦事也是在主線程中進行，如許可以安然點，防止主線程壅塞
		new Thread(new Runnable() {
			public void run() {
				startStepDetector();
			}
		}).start();

	}

	private void startStepDetector() {
		flag = true;
		stepDetector = new StepDetector(this);
		sensorManager = (SensorManager) this.getSystemService(SENSOR_SERVICE);//獲取傳感器治理器的實例
		Sensor sensor = sensorManager
				.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);//獲得傳感器的類型，這里獲得的類型是加快度傳感器
		//此辦法用來注冊，只有注冊過才會生效，參數(shù)：SensorEventListener的實例，Sensor的實例，更新速度
		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測試頁面的代碼也給大年夜家，如不雅大年夜家看過之前的博客，應(yīng)當(dāng)知道這是一個碎片。如不雅沒看過，看興趣的同伙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;

/**
 * 這是記步的碎片
 * Author: 李埡超   email:[email protected]
 * Date: 2015-1-6
 * Time: 下晝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;// 來斷定第三個頁面是否開啟動畫

	@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;
		}
		
	}

}

這些是重要的代碼，其他次要的我就不貼出來了，如不雅想要demo的同伙可以鄙人面留言，我給你們。
如不雅大年夜家有什么建議，可以提出來哦。