android中使用百度定位sdk实时的计算移动距离

/***************************************************

 * TODO: description .

 * @author: gao_chun

 * @version: 1.0.0

 * @remark: 转载请注明出处

 **************************************************/

前段时间因为项目需求，通过百度定位adk写了一个实时更新距离的程序（类似大家坐的士时，车上的里程表），遇到很多技术点，总结了一下发表出来和大家相互学习。直接要求定位具体的位置应该是不难的，只需要引入百度定位adk，并配置相关参数就可以完成，显示百度地图也类似，但是如果需要不断的实时显示移动距离，GPS定位从一个点，到第二个点，从第二个点，到第三个点，从第三个点......，移动距离是多少呢？不得不说，要实现这种需求的确存在一定的难度。

目标：使用百度定位sdk开发实时移动距离计算功能，根据经纬度的定位，计算行驶公里数并实时刷新界面显示。
大家都知道定位有三种方式：GPS 、Wifi 、 基站 .
误差方面的话，使用GPS误差在10左右，Wifi则在20 - 300左右 ，而使用基站则误差在100 - 300左右的样子，因为在室内GPS是定位不到的，必须在室外，
而我们项目的需求正好需要使用GPS定位，所以我们这里设置GPS优先。车，不可能在室内跑吧。


使用技术点：
1.百度定位sdk
2.sqlite数据库(用于保存经纬度和实时更新的距离)
3.通过经纬度计算距离的算法方式
4.TimerTask 、Handler


大概思路：
1）创建项目，上传应用到百度定位sdk获得应用对应key，并配置定位服务成功。
2）将配置的定位代码块放入service中，使程序在后台不断更新经纬度
3）为应用创建数据库和相应的数据表，编写 增删改查 业务逻辑方法
4）编写界面，通过点击按钮控制是否开始计算距离，并引用数据库，初始化表数据，实时刷新界面
5）在service的定位代码块中计算距离，并将距离和经纬度实时的保存在数据库(注：只要经纬度发生改变，计算出来的距离就要进行保存)

6）界面的刷新显示

文章后附源码下载链接

以下是MainActivity中的代码，通过注释可以理解思路流程.

package app.ui.activity;
    import java.util.Timer;
    import java.util.TimerTask;
    import android.content.Intent;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.view.View;
    import android.view.WindowManager;
    import android.widget.Button;
    import android.widget.TextView;
    import android.widget.Toast;
    import app.db.DistanceInfoDao;
    import app.model.DistanceInfo;
    import app.service.LocationService;
    import app.ui.ConfirmDialog;
    import app.ui.MyApplication;
    import app.ui.R;
    import app.utils.ConstantValues;
    import app.utils.LogUtil;
    import app.utils.Utils;

    public class MainActivity extends Activity {

        private TextView mTvDistance;                   //控件
        private Button mButton;
        private TextView mLng_lat;
        private boolean isStart = true;                 //是否开始计算移动距离

        private DistanceInfoDao mDistanceInfoDao;       //数据库
        private volatile boolean isRefreshUI = true;    //是否暂停刷新UI的标识
        private static final int REFRESH_TIME = 5000;   //5秒刷新一次

        private Handler refreshHandler = new Handler(){ //刷新界面的Handler
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case ConstantValues.REFRESH_UI:
                        if (isRefreshUI) {
                            LogUtil.info(DistanceComputeActivity.class, "refresh ui");
                            DistanceInfo mDistanceInfo = mDistanceInfoDao.getById(MyApplication.orderDealInfoId);
                            LogUtil.info(DistanceComputeActivity.class, "界面刷新---> "+mDistanceInfo);
                            if (mDistanceInfo != null) {
                                mTvDistance.setText(String.valueOf(Utils.getValueWith2Suffix(mDistanceInfo.getDistance())));
                                mLng_lat.setText("经:"+mDistanceInfo.getLongitude()+" 纬:"+mDistanceInfo.getLatitude());
                                mTvDistance.invalidate();
                                mLng_lat.invalidate();
                            }
                        }
                        break;
                }
                super.handleMessage(msg);
            }
        };

        //定时器，每5秒刷新一次UI
        private Timer refreshTimer = new Timer(true);
        private TimerTask refreshTask = new TimerTask() {
            @Override
            public void run() {
                if (isRefreshUI) {
                    Message msg = refreshHandler.obtainMessage();
                    msg.what = ConstantValues.REFRESH_UI;
                    refreshHandler.sendMessage(msg);
                }
            }
        };

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
                WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);    //保持屏幕常亮
            setContentView(R.layout.activity_expensecompute);

            startService(new Intent(this,LocationService.class));   //启动定位服务
            Toast.makeText(this,"已启动定位服务...", 1).show();
            init();                                                 //初始化相应控件
        }

        private void init(){
            mTvDistance = (TextView) findViewById(R.id.tv_drive_distance);
            mDistanceInfoDao = new DistanceInfoDao(this);
            refreshTimer.schedule(refreshTask, 0, REFRESH_TIME);
            mButton = (Button)findViewById(R.id.btn_start_drive);
            mLng_lat = (TextView)findViewById(R.id.longitude_Latitude);
        }


        @Override
        public void onClick(View v) {
            super.onClick(v);
            switch (v.getId()) {
                case R.id.btn_start_drive:      //计算距离按钮
                    if(isStart)
                    {
                        mButton.setBackgroundResource(R.drawable.btn_selected);
                        mButton.setText("结束计算");
                        isStart = false;
                        DistanceInfo mDistanceInfo = new DistanceInfo();
                        mDistanceInfo.setDistance(0f);                 //距离初始值
                        mDistanceInfo.setLongitude(MyApplication.lng); //经度初始值
                        mDistanceInfo.setLatitude(MyApplication.lat);  //纬度初始值
                        int id = mDistanceInfoDao.insertAndGet(mDistanceInfo);  //将值插入数据库，并获得数据库中最大的id
                        if (id != -1) {
                            MyApplication.orderDealInfoId = id;                 //将id赋值到程序全局变量中(注：该id来决定是否计算移动距离)
                            Toast.makeText(this,"已开始计算...", 0).show();
                        }else{
                            Toast.makeText(this,"id is -1,无法执行距离计算代码块", 0).show();
                        }
                    }else{
                        //自定义提示框
                        ConfirmDialog dialog = new ConfirmDialog(this, R.style.dialogNoFrame){
                            @Override
                            public void setDialogContent(TextView content) {
                                content.setVisibility(View.GONE);
                            }
                            @Override
                            public void setDialogTitle(TextView title) {
                                title.setText("确认结束计算距离 ？");
                            }
                            @Override
                            public void startMission() {
                                mButton.setBackgroundResource(R.drawable.btn_noselect);
                                mButton.setText("开始计算");
                                isStart = true;
                                isRefreshUI = false;    //停止界面刷新
                                if (refreshTimer != null) {
                                    refreshTimer.cancel();
                                    refreshTimer = null;
                                }
                                mDistanceInfoDao.delete(MyApplication.orderDealInfoId); //删除id对应记录
                                MyApplication.orderDealInfoId = -1; //停止定位计算
                                Toast.makeText(DistanceComputeActivity.this,"已停止计算...", 0).show();
                            }
                        };
                        dialog.show();
                    }
                    break;
            }
        }
    }

以下是LocationService中的代码，即配置的百度定位sdk代码块，放在继承了service的类中  LocationService.java (方便程序在后台实时更新经纬度)

package app.service;
    import java.util.concurrent.Callable;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import android.app.Service;
    import android.content.Intent;
    import android.os.IBinder;
    import app.db.DistanceInfoDao;
    import app.model.GpsLocation;
    import app.model.DistanceInfo;
    import app.ui.MyApplication;
    import app.utils.BDLocation2GpsUtil;
    import app.utils.FileUtils;
    import app.utils.LogUtil;
    import com.baidu.location.BDLocation;
    import com.baidu.location.BDLocationListener;
    import com.baidu.location.LocationClient;
    import com.baidu.location.LocationClientOption;
    import com.computedistance.DistanceComputeInterface;
    import com.computedistance.impl.DistanceComputeImpl;

    public class LocationService extends Service {

        public static final String FILE_NAME = "log.txt";                       //日志
        LocationClient mLocClient;
        private Object lock = new Object();
        private volatile GpsLocation prevGpsLocation = new GpsLocation();       //定位数据
        private volatile GpsLocation currentGpsLocation = new GpsLocation();
        private MyLocationListenner myListener = new MyLocationListenner();
        private volatile int discard = 1;   //Volatile修饰的成员变量在每次被线程访问时，都强迫从共享内存中重读该成员变量的值。
        private DistanceInfoDao mDistanceInfoDao;
        private ExecutorService executor = Executors.newSingleThreadExecutor();

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

        @Override
        public void onCreate() {
            super.onCreate();
            mDistanceInfoDao = new DistanceInfoDao(this);   //初始化数据库
            //LogUtil.info(LocationService.class, "Thread id ----------->:" + Thread.currentThread().getId());
            mLocClient = new LocationClient(this);
            mLocClient.registerLocationListener(myListener);
            //定位参数设置
            LocationClientOption option = new LocationClientOption();
            option.setCoorType("bd09ll"); //返回的定位结果是百度经纬度，默认值gcj02
            option.setAddrType("all");    //返回的定位结果包含地址信息
            option.setScanSpan(5000);     //设置发起定位请求的间隔时间为5000ms
            option.disableCache(true);    //禁止启用缓存定位
            option.setProdName("app.ui.activity");
            option.setOpenGps(true);
            option.setPriority(LocationClientOption.GpsFirst);  //设置GPS优先
            mLocClient.setLocOption(option);
            mLocClient.start();
            mLocClient.requestLocation();

        }

        @Override
        @Deprecated
        public void onStart(Intent intent, int startId) {
            super.onStart(intent, startId);
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            if (null != mLocClient) {
                mLocClient.stop();
            }
            startService(new Intent(this, LocationService.class));
        }

        private class Task implements Callable<String>{
            private BDLocation location;
            public Task(BDLocation location){
                this.location = location;
            }

            /**
             * 检测是否在原地不动
             *
             * @param distance
             * @return
             */
            private boolean noMove(float distance){
                if (distance < 0.01) {
                    return true;
                }
                return false;
            }

            /**
             * 检测是否在正确的移动
             *
             * @param distance
             * @return
             */
            private boolean checkProperMove(float distance){
                if(distance <= 0.1 * discard){
                    return true;
                }else{
                    return false;
                }
            }

            /**
             * 检测获取的数据是否是正常的
             *
             * @param location
             * @return
             */
            private boolean checkProperLocation(BDLocation location){
                if (location != null && location.getLatitude() != 0 && location.getLongitude() != 0){
                    return true;
                }
                return false;
            }

            @Override
            public String call() throws Exception {
                synchronized (lock) {
                    if (!checkProperLocation(location)){
                        LogUtil.info(LocationService.class, "location data is null");
                        discard++;
                        return null;
                    }

                    if (MyApplication.orderDealInfoId != -1) {
                        DistanceInfo mDistanceInfo = mDistanceInfoDao.getById(MyApplication.orderDealInfoId);   //根据MainActivity中赋值的全局id查询数据库的值
                        if(mDistanceInfo != null)       //不为空则说明车已经开始行使，并可以获得经纬度，计算移动距离
                        {
                            LogUtil.info(LocationService.class, "行驶中......");
                            GpsLocation tempGpsLocation = BDLocation2GpsUtil.convertWithBaiduAPI(location);     //位置转换
                            if (tempGpsLocation != null) {
                                currentGpsLocation = tempGpsLocation;
                            }else{
                                discard ++;
                            }
                            //日志
                            String logMsg = "(plat:--->" + prevGpsLocation.lat + "  plgt:--->" + prevGpsLocation.lng +")\n" +
                                            "(clat:--->" + currentGpsLocation.lat + "  clgt:--->" + currentGpsLocation.lng + ")";
                            LogUtil.info(LocationService.class, logMsg);

                            /** 计算距离  */
                            float distance = 0.0f;
                            DistanceComputeInterface distanceComputeInterface = DistanceComputeImpl.getInstance();  //计算距离类对象
                            distance = (float) distanceComputeInterface.getLongDistance(prevGpsLocation.lat,prevGpsLocation.lng,
                            currentGpsLocation.lat,currentGpsLocation.lng);     //移动距离计算
                            if (!noMove(distance)) {                //是否在移动
                                if (checkProperMove(distance)) {    //合理的移动
                                    float drivedDistance = mDistanceInfo.getDistance();
                                    mDistanceInfo.setDistance(distance + drivedDistance); //拿到数据库原始距离值， 加上当前值
                                    mDistanceInfo.setLongitude(currentGpsLocation.lng);   //经度
                                    mDistanceInfo.setLatitude(currentGpsLocation.lat);    //纬度

                                    //日志记录
                                    FileUtils.saveToSDCard(FILE_NAME,"移动距离--->:"+distance+drivedDistance+"\n"+"数据库中保存的距离"+mDistanceInfo.getDistance());
                                    mDistanceInfoDao.updateDistance(mDistanceInfo);
                                    discard = 1;
                                }
                            }
                            prevGpsLocation = currentGpsLocation;
                        }
                    }
                    return null;
                }
            }
        }

        /**
         * 定位SDK监听函数
         */
        public class MyLocationListenner implements BDLocationListener {
            @Override
            public void onReceiveLocation(BDLocation location) {
                executor.submit(new Task(location));

                LogUtil.info(LocationService.class, "经度："+location.getLongitude());
                LogUtil.info(LocationService.class, "纬度："+location.getLatitude());
                //将经纬度保存于全局变量，在MainActivity中点击按钮时初始化数据库字段
                if(MyApplication.lng <=0 && MyApplication.lat <= 0)
                {
                    MyApplication.lng = location.getLongitude();
                    MyApplication.lat = location.getLatitude();
                }
            }

            public void onReceivePoi(BDLocation poiLocation) {
                if (poiLocation == null){
                    return ;
                }
            }
        }
    }

以下是应用中需要使用的DBOpenHelper数据库类 DBOpenHelper.java

package app.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBOpenHelper extends SQLiteOpenHelper{
    private static final int VERSION = 1;                   //数据库版本号
    private static final String DB_NAME = "distance.db";    //数据库名

    public DBOpenHelper(Context context){                   //创建数据库
        super(context, DB_NAME, null, VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {               //创建数据表
        db.execSQL("CREATE TABLE IF NOT EXISTS milestone(id INTEGER PRIMARY KEY AUTOINCREMENT, distance INTEGER,longitude DOUBLE, latitude DOUBLE )");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {  //版本号发生改变的时
        db.execSQL("drop table milestone");
        db.execSQL("CREATE TABLE IF NOT EXISTS milestone(id INTEGER PRIMARY KEY AUTOINCREMENT, distance INTEGER,longitude FLOAT, latitude FLOAT )");
    }

}

以下是应用中需要使用的数据库业务逻辑封装类 DistanceInfoDao.java

package app.db;
    import android.content.Context;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import app.model.DistanceInfo;
    import app.utils.LogUtil;

    public class DistanceInfoDao {
        private DBOpenHelper helper;
        private SQLiteDatabase db;

        public DistanceInfoDao(Context context) {
            helper = new DBOpenHelper(context);
        }

        public void insert(DistanceInfo mDistanceInfo) {
            if (mDistanceInfo == null) {
                return;
            }
            db = helper.getWritableDatabase();
            String sql = "INSERT INTO milestone(distance,longitude,latitude) VALUES('"+ mDistanceInfo.getDistance() + "','"+ mDistanceInfo.getLongitude() + "','"+ mDistanceInfo.getLatitude() + "')";
            LogUtil.info(DistanceInfoDao.class, sql);
            db.execSQL(sql);
            db.close();
        }

        public int getMaxId() {
            db = helper.getReadableDatabase();
            Cursor cursor = db.rawQuery("SELECT MAX(id) as id from milestone",null);
            if (cursor.moveToFirst()) {
                return cursor.getInt(cursor.getColumnIndex("id"));
            }
            return -1;
        }

        /**
         * 添加数据
         * @param orderDealInfo
         * @return
         */
        public synchronized int insertAndGet(DistanceInfo mDistanceInfo) {
            int result = -1;
            insert(mDistanceInfo);
            result = getMaxId();
            return result;
        }

        /**
         * 根据id获取
         * @param id
         * @return
         */
        public DistanceInfo getById(int id) {
            db = helper.getReadableDatabase();
            Cursor cursor = db.rawQuery("SELECT * from milestone WHERE id = ?",new String[] { String.valueOf(id) });
            DistanceInfo mDistanceInfo = null;
            if (cursor.moveToFirst()) {
                mDistanceInfo = new DistanceInfo();
                mDistanceInfo.setId(cursor.getInt(cursor.getColumnIndex("id")));
                mDistanceInfo.setDistance(cursor.getFloat(cursor.getColumnIndex("distance")));
                mDistanceInfo.setLongitude(cursor.getFloat(cursor.getColumnIndex("longitude")));
                mDistanceInfo.setLatitude(cursor.getFloat(cursor.getColumnIndex("latitude")));
            }
            cursor.close();
            db.close();
            return mDistanceInfo;
        }

        /**
         * 更新距离
         * @param orderDealInfo
         */
        public void updateDistance(DistanceInfo mDistanceInfo) {
            if (mDistanceInfo == null) {
                return;
            }
            db = helper.getWritableDatabase();
            String sql = "update milestone set distance="+ mDistanceInfo.getDistance() +",longitude="+mDistanceInfo.getLongitude()+",latitude="+mDistanceInfo.getLatitude()+" where id = "+ mDistanceInfo.getId();
            LogUtil.info(DistanceInfoDao.class, sql);
            db.execSQL(sql);
            db.close();
        }
    }

以下是需要使用到的实体类 DistanceInfo.java (set数据到对应变量，以实体类作为参数更新数据库)

package app.model;
public class DistanceInfo {
    private int id;
    private float distance;
    private double longitude;
    private double latitude;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public float getDistance() {
        return distance;
    }
    public void setDistance(float distance) {
        this.distance = distance;
    }
    public double getLongitude() {

        return longitude;
    }
    public void setLongitude(double longitude) {

        this.longitude = longitude;
    }
    public double getLatitude() {

        return latitude;
    }
    public void setLatitude(double latitude) {

        this.latitude = latitude;
    }
    @Override
    public String toString() {

        return "DistanceInfo [id=" + id + ", distance=" + distance
                + ", longitude=" + longitude + ", latitude=" + latitude + "]";
    }
}

保存经纬度信息的类 GpsLocation

package app.model;
public class GpsLocation {
    public double lat;//纬度
    public double lng;//经度
}

将从百度定位中获得的经纬度转换为精准的GPS数据 BDLocation2GpsUtil.java

package app.utils;
import it.sauronsoftware.base64.Base64;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import org.json.JSONObject;
import app.model.GpsLocation;
import com.baidu.location.BDLocation;
public class BDLocation2GpsUtil {
    static BDLocation tempBDLocation = new BDLocation();     // 临时变量，百度位置
    static GpsLocation tempGPSLocation = new GpsLocation();  // 临时变量，gps位置
    public static enum Method{
        origin, correct;
    }
    private static final Method method = Method.correct;
    /**
     * 位置转换
     *
     * @param lBdLocation 百度位置
     * @return GPS位置
     */
    public static GpsLocation convertWithBaiduAPI(BDLocation lBdLocation) {
        switch (method) {
        case origin:    //原点
            GpsLocation location = new GpsLocation();
            location.lat = lBdLocation.getLatitude();
            location.lng = lBdLocation.getLongitude();
            return location;
        case correct:   //纠偏
            //同一个地址不多次转换
            if (tempBDLocation.getLatitude() == lBdLocation.getLatitude() && tempBDLocation.getLongitude() == lBdLocation.getLongitude()) {
                return tempGPSLocation;
            }
            String url = "http://api.map.baidu.com/ag/coord/convert?from=0&to=4&"
                    + "x=" + lBdLocation.getLongitude() + "&y="
                    + lBdLocation.getLatitude();
            String result = executeHttpGet(url);
            LogUtil.info(BDLocation2GpsUtil.class, "result:" + result);
            if (result != null) {
                GpsLocation gpsLocation = new GpsLocation();
                try {
                    JSONObject jsonObj = new JSONObject(result);
                    String lngString = jsonObj.getString("x");
                    String latString = jsonObj.getString("y");
                    // 解码
                    double lng = Double.parseDouble(new String(Base64.decode(lngString)));
                    double lat = Double.parseDouble(new String(Base64.decode(latString)));
                    // 换算
                    gpsLocation.lng = 2 * lBdLocation.getLongitude() - lng;
                    gpsLocation.lat = 2 * lBdLocation.getLatitude() - lat;
                    tempGPSLocation = gpsLocation;
                    LogUtil.info(BDLocation2GpsUtil.class, "result:" + gpsLocation.lat + "||" + gpsLocation.lng);
                } catch (Exception e) {
                    e.printStackTrace();
                    return null;
                }
                tempBDLocation = lBdLocation;
                return gpsLocation;
            }else{
                LogUtil.info(BDLocation2GpsUtil.class, "百度API执行出错,url is:" + url);
                return null;
            }
        }
    }
}

需要声明相关权限，且项目中所用到的jar有：
android-support-v4.jar
commons-codec.jar
commons-lang3-3.0-beta.jar
javabase64-1.3.1.jar
locSDK_3.1.jar

Android中计算地图上两点距离的算法

项目中目前尚有部分不健全的地方，如：
1.在行驶等待时间较长后，使用TimerTask 、Handler刷新界面是偶尔会出现卡住的现象，车仍在行驶，
但是数据不动了，通过改善目前测试近7次未出现此问题。

2.较快的消耗电量

源码下载地址

【转载注明gao_chun的Blog：http://blog.csdn.net/gao_chun/article/details/38229339】