Question

我正在使用android studio 3.1.4来学习开发android应用。我正在尝试获取GPS位置。但是，它不起作用。我整天都在尝试这个。拜托，有人帮我解决这个问题。

我的gpsTracker类

package com.prios.pratice;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;


public class GPSTracker extends AppCompatActivity implements LocationListener 
{
    private LocationManager locationManager;
    private String provider, LOCATION = "N/A";


    public String getLocation() {

        // Get the location manager
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        // Define the criteria how to select the locatioin provider -> use
        // default
        Criteria criteria = new Criteria();
        provider = locationManager.getBestProvider(criteria, false);
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, 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 "Cannot Get Location!";
        }
        Location location = locationManager.getLastKnownLocation(provider);

        // Initialize the location fields
        if (location != null) {
            System.out.println("Provider " + provider + " has been selected.");
            onLocationChanged(location);
        } else {
            Log.d("Location:", "Not Available");
        }

        return LOCATION;

        // Boolean isGPSenabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
    }

    /* Request updates at startup */
    @Override
    protected void onResume() {
        super.onResume();
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, 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;
        }
        locationManager.requestLocationUpdates(provider, 400, 1, this);
    }

    /* Remove the locationlistener updates when Activity is paused */
    @Override
    protected void onPause() {
        super.onPause();
        locationManager.removeUpdates(this);
    }

    @Override
    public void onLocationChanged(Location location) {
        int lat = (int) (location.getLatitude());
        int lng = (int) (location.getLongitude());
        Log.d("Location:", lat+", "+lng);
        LOCATION = lat + ", " + lng;
    }

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

    }

    @Override
    public void onProviderEnabled(String provider) {
        Toast.makeText(this, "Enabled new provider " + provider,
                Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onProviderDisabled(String provider) {
        Toast.makeText(this, "Disabled provider " + provider,
                Toast.LENGTH_SHORT).show();
    }


}

我的清单文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.prios.practice">
    <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"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

当我尝试在设备上运行它时，它关闭并且什么也没有显示。我的设备已启用位置信息。

我的HomeFragment类：

package com.prios.practice;

import android.app.Activity;
import android.content.Context;
import android.location.OnNmeaMessageListener;
import android.os.Bundle;
//import android.support.v4.app.Fragment;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;


/**
 * A simple {@link Fragment} subclass.
 */
public class HomeFragment extends Fragment {

    private Button;

    private GPSTracker gpsTracker;

    public HomeFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view =  inflater.inflate(R.layout.fragment_home, container, false);
        String location = gpsTracker.getLocation();
        Toast.makeText(getActivity(), location, Toast.LENGTH_SHORT).show();
        return view;
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        Activity activity = (Activity) context;
    }

    @Override
    public void onResume() {
        super.onResume();

    }

}

Answer 1

您还需要在运行时（通过代码）请求权限。

在使用与位置相关的内容之前，请调用方法ActivityCompat#requestPermissions()。

有关详细信息，请阅读文档：https://developer.android.com/training/permissions/requesting

Answer 2

为什么GPSTracker继承AppCompatActivity？您不能在片段中像这样使用它。

GPSTracker必须是Singleton或类似的东西，但与Activity不相关...

您已阅读本指南吗？ https://developer.android.com/training/location/receive-location-updates

Answer 3

终于可以了。

package com.prios.practice;

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;


public class GPSTracker extends AppCompatActivity implements LocationListener {

    private LocationManager locationManager;
    private String provider, LOCATION="N/A";
    private Context context;
    private Activity activity;

    public GPSTracker(Activity activity) {
        this.context = activity.getApplicationContext();
        this.activity = activity;
        // Get the location manager
        locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        // Define the criteria how to select the locatioin provider -> use
        // default
        Criteria criteria = new Criteria();
        provider = locationManager.getBestProvider(criteria, false);
        if (ActivityCompat.checkSelfPermission(context, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.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.
            ActivityCompat.requestPermissions(this.activity,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    99);
        }
        Location location = locationManager.getLastKnownLocation(provider);
        if (location != null) {
            Log.e("TAG", "GPS is on");
            LOCATION = location.getLatitude()+","+location.getLongitude();
        }
        else{
            //This is what you need:
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, this);
        }
    }

    public String getLocation() {
        return LOCATION;
    }

    @Override
    public void onLocationChanged(Location location) {
        if(location!=null) {
            locationManager.removeUpdates(this);
            Double lat = (Double) (location.getLatitude());
            Double lng = (Double) (location.getLongitude());
            LOCATION = lat.toString() + "," + lng.toString();
//          Toast.makeText(this, LOCATION, Toast.LENGTH_SHORT).show();
        }
    }

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

    }

    @Override
    public void onProviderEnabled(String provider) {
//        Toast.makeText(this, "Enabled new provider " + provider,
//                Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onProviderDisabled(String provider) {
//        Toast.makeText(this, "Disabled provider " + provider,
//                Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
            case 99: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                    // permission was granted, yay! Do the
                    // location-related task you need to do.
                    if (ContextCompat.checkSelfPermission(context,
                            Manifest.permission.ACCESS_FINE_LOCATION)
                            == PackageManager.PERMISSION_GRANTED) {

                        //Request location updates:
                        locationManager.requestLocationUpdates(provider, 400, 1, this);
                    }

                } else {

                    // permission denied, boo! Disable the
                    // functionality that depends on this permission.

                }
                return;
            }

        }
    }
}

如何获取位置？

3 个答案: