How to get current location in Android [duplicate]

2018-12-31 19:30发布

站内文章 / Java
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问题:

This question already has an answer here:

  • How do I get the current GPS location programmatically in Android? 21 answers

I\'m having troubles of getting my current position coordinates using the NETWORK provider of android location system.

Already read a lot of tutorials and implemented 4 or 5 existing classes to my project and all of them are giving me the last coordinates but not the current ones.

I\'m pretty sure that the problem is something fundamental that I am missing but I am not able to understand what exactly it is.

Codes I\'m using now:

This is my main Activity 

package com.example.locationtests;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    GPSTracker mGPS = new GPSTracker(this);

    TextView text = (TextView) findViewById(R.id.texts);
    if(mGPS.canGetLocation ){
    mGPS.getLocation();
    text.setText(\"Lat\"+mGPS.getLatitude()+\"Lon\"+mGPS.getLongitude());
    }else{
        text.setText(\"Unabletofind\");
        System.out.println(\"Unable\");
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

This is the class I\'m using for Tracking:

package com.example.locationtests;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.provider.Settings;
import android.util.Log;

public final class GPSTracker implements LocationListener {

    private final Context mContext;

    // flag for GPS status
    public boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS status
    boolean canGetLocation = false;

    Location location; // location
    double latitude; // latitude
    double longitude; // longitude

    // The minimum distance to change Updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 1; // 10 meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1; // 1 minute

    // Declaring a Location Manager
    protected LocationManager locationManager;

    public GPSTracker(Context context) {
        this.mContext = context;
        getLocation();
    }

    /**
     * Function to get the user\'s current location
     * 
     * @return
     */
    public Location getLocation() {
        try {
            locationManager = (LocationManager) mContext
                    .getSystemService(Context.LOCATION_SERVICE);

            // getting GPS status
            isGPSEnabled = locationManager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);

            Log.v(\"isGPSEnabled\", \"=\" + isGPSEnabled);

            // getting network status
            isNetworkEnabled = locationManager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            Log.v(\"isNetworkEnabled\", \"=\" + isNetworkEnabled);

            if (isGPSEnabled == false && isNetworkEnabled == false) {
                // no network provider is enabled
            } else {
                this.canGetLocation = true;
                if (isNetworkEnabled) {
                    location=null;
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d(\"Network\", \"Network\");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    location=null;
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                        Log.d(\"GPS Enabled\", \"GPS Enabled\");
                        if (locationManager != null) {
                            location = locationManager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }

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

        return location;
    }

    /**
     * Stop using GPS listener Calling this function will stop using GPS in your
     * app
     * */
    public void stopUsingGPS() {
        if (locationManager != null) {
            locationManager.removeUpdates(GPSTracker.this);
        }
    }

    /**
     * Function to get latitude
     * */
    public double getLatitude() {
        if (location != null) {
            latitude = location.getLatitude();
        }

        // return latitude
        return latitude;
    }

    /**
     * Function to get longitude
     * */
    public double getLongitude() {
        if (location != null) {
            longitude = location.getLongitude();
        }

        // return longitude
        return longitude;
    }

    /**
     * Function to check GPS/wifi enabled
     * 
     * @return boolean
     * */
    public boolean canGetLocation() {
        return this.canGetLocation;
    }

    /**
     * Function to show settings alert dialog On pressing Settings button will
     * lauch Settings Options
     * */
    public void showSettingsAlert() {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

        // Setting Dialog Title
        alertDialog.setTitle(\"GPS is settings\");

        // Setting Dialog Message
        alertDialog
                .setMessage(\"GPS is not enabled. Do you want to go to settings menu?\");

        // On pressing Settings button
        alertDialog.setPositiveButton(\"Settings\",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        Intent intent = new Intent(
                                Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                        mContext.startActivity(intent);
                    }
                });

        // on pressing cancel button
        alertDialog.setNegativeButton(\"Cancel\",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                    }
                });

        // Showing Alert Message
        alertDialog.show();
    }

    @Override
    public void onLocationChanged(Location location) {
    }

    @Override
    public void onProviderDisabled(String provider) {
    }

    @Override
    public void onProviderEnabled(String provider) {
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }

}

This is my AndroidManifest.xml

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<manifest xmlns:android=\"http://schemas.android.com/apk/res/android\"
    package=\"com.example.locationtests\"
    android:versionCode=\"1\"
    android:versionName=\"1.0\" >
    <uses-permission android:name=\"android.permission.CAMERA\" />
    <uses-permission android:name=\"android.permission.ACCESS_FINE_LOCATION\" />
    <uses-permission android:name=\"android.permission.ACCESS_COARSE_LOCATION\" />
    <uses-permission android:name=\"android.permission.INTERNET\"></uses-permission>
    <uses-permission android:name=\"android.permission.ACCESS_WIFI_STATE\" /> 
    <uses-permission android:name=\"android.permission.ACCESS_NETWORK_STATE\" />
    <uses-permission android:name=\"android.permission.VIBRATE\" />
    <uses-feature android:name=\"android.hardware.camera\" />
    <uses-feature android:name=\"android.hardware.location\" android:required=\"true\" />
    <uses-feature android:name=\"android.hardware.location.gps\" android:required=\"false\" />

    <uses-sdk
        android:minSdkVersion=\"8\"
        android:targetSdkVersion=\"17\" />

    <application
        android:allowBackup=\"true\"
        android:icon=\"@drawable/ic_launcher\"
        android:label=\"@string/app_name\"
        android:theme=\"@style/AppTheme\" >
        <activity
            android:name=\"com.example.locationtests.MainActivity\"
            android:label=\"@string/app_name\" >
            <intent-filter>
                <action android:name=\"android.intent.action.MAIN\" />

                <category android:name=\"android.intent.category.LAUNCHER\" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Acctualy GPS possitioning works fine, but NETWORK positioning dosn\'t. When Ive turned devices GPS on cordinates keep changing while im moving, but dosnt happence same when I have turn it off and relay on the NETWORK_PROVIDER

回答1:

First you need to define a LocationListener to handle location changes.

private final LocationListener mLocationListener = new LocationListener() {
    @Override
    public void onLocationChanged(final Location location) {
        //your code here
    }
};

Then get the LocationManager and ask for location updates

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    mLocationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, LOCATION_REFRESH_TIME,
            LOCATION_REFRESH_DISTANCE, mLocationListener);
}

And finally make sure that you have added the permission on the Manifest,

For using only network based location use this one

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

For GPS based location, this one

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


回答2:

You need to write code in the OnLocationChanged method, because this method is called when the location has changed. I.e. you need to save the new location to return it if getLocation is called.

If you don\'t use the onLocationChanged it always will be the old location.



回答3:

I\'m using this tutorial and it works nicely for my application.

In my activity I put this code:

GPSTracker tracker = new GPSTracker(this);
    if (!tracker.canGetLocation()) {
        tracker.showSettingsAlert();
    } else {
        latitude = tracker.getLatitude();
        longitude = tracker.getLongitude();
    }

also check if your emulator runs with Google API



标签： java android gps geolocation android-location
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