在android中使用GPS确定车辆速度

我想知道坐在车上使用gps时如何使用手机获取车辆速度。我读到加速度计不是很准确。另一件事是；坐在车内时是否可以使用GPS。它不会有和你在大楼里时一样的效果吗

以下是我尝试过的一些代码，但我使用了网络提供商。我将感谢您的帮助。谢谢

package com.example.speedtest;

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends Activity {
    LocationManager locManager;
    LocationListener li;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        locManager=(LocationManager)getSystemService(Context.LOCATION_SERVICE);
        li=new speed();
        locManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, li);
    }
    class speed implements LocationListener{
        @Override
        public void onLocationChanged(Location loc) {
            Float thespeed=loc.getSpeed();
            Toast.makeText(MainActivity.this,String.valueOf(thespeed), Toast.LENGTH_LONG).show();
        }
        @Override
        public void onProviderDisabled(String arg0) {}
        @Override
        public void onProviderEnabled(String arg0) {}
        @Override
        public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}

    }
}

---

GPS在车辆上工作正常。

NETWORK\u PROVIDER

设置可能不够精确，无法获得可靠的速度，而且

NETWORK\u PROVIDER

中的位置甚至可能不包含速度。您可以使用

location.hasSpeed（）

（

location.getSpeed（）

将始终返回0）

如果您发现

location.getSpeed（）

不够精确，或者不稳定（即波动剧烈），则您可以通过计算几个GPS位置之间的平均距离并除以经过的时间来计算速度

主要有两种计算手机速度的方法

从加速度计计算速度

利用GPS技术计算速度

与GPS技术中的加速度计不同，如果要计算速度，必须启用数据连接和GPS连接

在这里，我们将使用GPS连接计算速度。 在该方法中，我们使用GPS定位点在单个时间段内的变化频率。然后，如果我们有地理位置点之间的实际距离，我们可以得到速度。因为我们有距离和时间。 速度=距离/时间 但是获得两个定位点之间的距离并不容易。因为世界在形状上是一个目标，所以两个地理点之间的距离因地点和角度而异。所以我们必须使用

首先，我们必须授予在清单文件中获取位置数据的权限

制作GUI

使用GPS位置实现获取速度的逻辑

将逻辑与GUI相结合

如果要将米/秒转换为kmph-1，则需要将米/秒答案从3.6乘以

从kmph-1开始的速度=3.6*（从ms-1开始的速度）

在“活动”旁边添加implements

LocationListener

LocationManager lm =(LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
        this.onLocationChanged(null);

LocationManager.GPS\u PROVIDER，0，0，

第一个零表示

minTime

，第二个零表示更新值的

minDistance

。零意味着基本上是即时更新，这可能会影响电池寿命，所以您可能需要调整它

     @Override
    public void onLocationChanged(Location location) {

    if (location==null){
         // if you can't get speed because reasons :)
        yourTextView.setText("00 km/h");
    }
    else{
        //int speed=(int) ((location.getSpeed()) is the standard which returns meters per second. In this example i converted it to kilometers per hour

        int speed=(int) ((location.getSpeed()*3600)/1000);

        yourTextView.setText(speed+" km/h");
    }
}


@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

}


@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub

}


@Override
public void onProviderDisabled(String provider) {


}

别忘了权限

 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

---

我们可以使用location.getSpeed（）

---

Thanx，我曾想过手动计算速度，直到找到便利功能。网络提供商给了我一个0.0的值。我猜这意味着它没有速度。再次感谢。location.getSpeed（）的单位是多少？km/h、M/h、ft/sec、mtrs/sect文档中说，米/秒使用此功能，由于每次调用onlocation change后都会延迟获取速度。我们能做些什么使它完美无瑕呢？我扩展了

android.location.LocationListener

（

com.google.android.gms.location.LocationListener

）

import java.util.Formatter;
import java.util.Locale;

import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.view.Menu;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.TextView;

public class MainActivity extends Activity implements IBaseGpsListener {

      @Override
      protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
            this.updateSpeed(null);

            CheckBox chkUseMetricUntis = (CheckBox) this.findViewById(R.id.chkMetricUnits);
            chkUseMetricUntis.setOnCheckedChangeListener(new OnCheckedChangeListener() {

                  @Override
                  public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                        // TODO Auto-generated method stub
                        MainActivity.this.updateSpeed(null);
                  }
            });
      }

      public void finish()
      {
            super.finish();
            System.exit(0);
      }

      private void updateSpeed(CLocation location) {
            // TODO Auto-generated method stub
            float nCurrentSpeed = 0;

            if(location != null)
            {
                  location.setUseMetricunits(this.useMetricUnits());
                  nCurrentSpeed = location.getSpeed();
            }

            Formatter fmt = new Formatter(new StringBuilder());
            fmt.format(Locale.US, "%5.1f", nCurrentSpeed);
            String strCurrentSpeed = fmt.toString();
            strCurrentSpeed = strCurrentSpeed.replace(' ', '0');

            String strUnits = "miles/hour";
            if(this.useMetricUnits())
            {
                  strUnits = "meters/second";
            }

            TextView txtCurrentSpeed = (TextView) this.findViewById(R.id.txtCurrentSpeed);
            txtCurrentSpeed.setText(strCurrentSpeed + " " + strUnits);
      }

      private boolean useMetricUnits() {
            // TODO Auto-generated method stub
            CheckBox chkUseMetricUnits = (CheckBox) this.findViewById(R.id.chkMetricUnits);
            return chkUseMetricUnits.isChecked();
      }

      @Override
      public void onLocationChanged(Location location) {
            // TODO Auto-generated method stub
            if(location != null)
            {
                  CLocation myLocation = new CLocation(location, this.useMetricUnits());
                  this.updateSpeed(myLocation);
            }
      }

      @Override
      public void onProviderDisabled(String provider) {
            // TODO Auto-generated method stub

      }

      @Override
      public void onProviderEnabled(String provider) {
            // TODO Auto-generated method stub

      }

      @Override
      public void onStatusChanged(String provider, int status, Bundle extras) {
            // TODO Auto-generated method stub

      }

      @Override
      public void onGpsStatusChanged(int event) {
            // TODO Auto-generated method stub

      }



}

public class MainActivity extends Activity implements LocationListener {

LocationManager lm =(LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
        this.onLocationChanged(null);

     @Override
    public void onLocationChanged(Location location) {

    if (location==null){
         // if you can't get speed because reasons :)
        yourTextView.setText("00 km/h");
    }
    else{
        //int speed=(int) ((location.getSpeed()) is the standard which returns meters per second. In this example i converted it to kilometers per hour

        int speed=(int) ((location.getSpeed()*3600)/1000);

        yourTextView.setText(speed+" km/h");
    }
}


@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

}


@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub

}


@Override
public void onProviderDisabled(String provider) {


}

 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

  try {
                // Get the location manager
                double lat;
                double lon;
                double speed = 0;
                LocationManager locationManager = (LocationManager)
                        getActivity().getSystemService(LOCATION_SERVICE);
                Criteria criteria = new Criteria();
                String bestProvider = locationManager.getBestProvider(criteria, false);
                if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                }
                Location location = locationManager.getLastKnownLocation(bestProvider);
                try {
                    lat = location.getLatitude();
                    lon = location.getLongitude();
                    speed =location.getSpeed();
                } catch (NullPointerException e) {
                    lat = -1.0;
                    lon = -1.0;
                }

                mTxt_lat.setText("" + lat);
                mTxt_speed.setText("" + speed);

            }catch (Exception ex){
                ex.printStackTrace();
            }