如何使用 LocationManager 在 android 中获取当前位置

Posted 2023-04-14

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【中文标题】如何使用 LocationManager 在 android 中获取当前位置【英文标题】：How to get current location in android with LocationManager 【发布时间】：2018-12-19 11:18:51 【问题描述】：

每当我使用 LocationManager 和 LocationListener 时，在使用 androidEmulator 时，我得到了位置，设置纬度和经度时使用额外的工具

我查看了其他问题答案，但我是 Android 开发的新手，所以我真的无法理解答案。所以我提出了一个新问题，我希望能对我的代码进行审查。谢谢。

但是当我在物理设备上运行时，我的代码在启动时并没有给出我当前的位置。如何获取当前位置？我也试过 getLastKnownLocation 但即使这样也不起作用。

package com.londonappbrewery.climapm;

import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.JsonHttpResponseHandler;
import com.loopj.android.http.RequestParams;

import org.json.JSONObject;

import cz.msebera.android.httpclient.Header;


public class WeatherController extends AppCompatActivity 

    // Constants:
    final String WEATHER_URL = "http://api.openweathermap.org/data/2.5/weather";
    // App ID to use OpenWeather data
    final String APP_ID = "5563c6a4ddd7d7181b257988cc2b1ad1";
    // Time between location updates (5000 milliseconds or 5 seconds)
    final long MIN_TIME = 5000;
    // Distance between location updates (1000m or 1km)
    final float MIN_DISTANCE = 1000;
    //Request Code
    final int REQUEST_CODE = 123;

    // TODO: Set LOCATION_PROVIDER here:
    String LOCATION_PROVIDER = LocationManager.GPS_PROVIDER;


    // Member Variables:
    TextView mCityLabel;
    ImageView mWeatherImage;
    TextView mTemperatureLabel;

    // TODO: Declare a LocationManager and a LocationListener here:
    LocationManager mLocationManager;
    LocationListener mLocationListener;


    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.weather_controller_layout);

        // Linking the elements in the layout to Java code
        mCityLabel = (TextView) findViewById(R.id.locationTV);
        mWeatherImage = (ImageView) findViewById(R.id.weatherSymbolIV);
        mTemperatureLabel = (TextView) findViewById(R.id.tempTV);
        ImageButton changeCityButton = (ImageButton) findViewById(R.id.changeCityButton);


        // TODO: Add an OnClickListener to the changeCityButton here:
        changeCityButton.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                Intent intent = new Intent(WeatherController.this, ChangeCityController.class);
                startActivity(intent);
            
        );

    


    // TODO: Add onResume() here:
    @Override
    protected void onResume() 
        super.onResume();

        Log.d("Clima", "onResume() called");

        Intent intent = getIntent();
        String cityName = intent.getStringExtra("cityName");

        if (cityName != null) 

            //Log.d("Clima", cityName);
            getWeatherForNewCity(cityName);

         else 
            Log.d("Clima", "Getting weather for current location");
            getWeatherForCurrentLocation();
        


    


    // TODO: Add getWeatherForNewCity(String city) here:
    private void getWeatherForNewCity(String city) 

        RequestParams params = new RequestParams();
        params.put("q", city);
        params.put("appid", APP_ID);
        letsDoSomeNetworking(params);

    

    // TODO: Add getWeatherForCurrentLocation() here:
    private void getWeatherForCurrentLocation() 

        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        mLocationListener = new LocationListener() 
            @Override
            public void onLocationChanged(Location location) 

                //Log.d("Clima", "");

                String latitude = String.valueOf(location.getLatitude());
                String longitude = String.valueOf(location.getLongitude());

                Log.d("Clima", "onLocationChanged() callback received");
                Log.d("Clima", "Latitude is " + latitude);
                Log.d("Clima", "Longitude is " + longitude);

                RequestParams params = new RequestParams();
                params.put("lat", latitude);
                params.put("lon", longitude);
                params.put("appid", APP_ID);
                letsDoSomeNetworking(params);


            

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

            

            @Override
            public void onProviderEnabled(String provider) 

            

            @Override
            public void onProviderDisabled(String provider) 

                Log.d("Clima", "onProviderDisabled() callback received");

            
        ;

        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.

            ActivityCompat.requestPermissions(this, new String[]Manifest.permission.ACCESS_FINE_LOCATION, REQUEST_CODE);

            return;
        

        mLocationManager.requestLocationUpdates(LOCATION_PROVIDER, MIN_TIME, MIN_DISTANCE, mLocationListener);
        Location location = mLocationManager.getLastKnownLocation(LOCATION_PROVIDER);
        if(location != null) 
            RequestParams params = new RequestParams();
            params.put("lat", location.getLatitude());
            params.put("lon", location.getLongitude());
            params.put("appid", APP_ID);
            letsDoSomeNetworking(params);
        

    

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) 
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        if (requestCode == REQUEST_CODE) 

            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) 

                Log.d("Clima", "onRequestPermissionResult(): Permission Granted!");
                //mLocationManager.requestLocationUpdates(LOCATION_PROVIDER, MIN_TIME, MIN_DISTANCE, mLocationListener);
                getWeatherForCurrentLocation();


            

        

    

    // TODO: Add letsDoSomeNetworking(RequestParams params) here:
    private void letsDoSomeNetworking(RequestParams params) 

        AsyncHttpClient client = new AsyncHttpClient();

        client.get(WEATHER_URL, params, new JsonHttpResponseHandler() 

            @Override
            public void onSuccess(int statusCode, Header[] header, JSONObject response) 

                Log.d("Clima", "Success! JSON : " + response.toString());

                WeatherDataModel weatherData = WeatherDataModel.fromJSON(response);

                // Log.d("Clima", weatherData.getTemperature()); << WORKING

                updateUI(weatherData);
            

            @Override
            public void onFailure(int statusCode, Header[] header, Throwable e, JSONObject response) 
                Log.e("Clima", e.toString());
                Log.d("Clima", String.valueOf(statusCode));
                Toast.makeText(WeatherController.this, "Request Failed!", Toast.LENGTH_SHORT).show();

            

        );

    


    // TODO: Add updateUI() here:
    private void updateUI(WeatherDataModel weatherData)

        mTemperatureLabel.setText(weatherData.getTemperature());
        mCityLabel.setText(weatherData.getCity());

        int resourceID = getResources().getIdentifier(weatherData.getIconName(), "drawable", getPackageName());
        mWeatherImage.setImageResource(resourceID);



    


    // TODO: Add onPause() here:

应用启动后我应该怎么做才能获取位置？

附：权限已经到位，所以这不是权限问题。

【问题讨论】：

What is the simplest and most robust way to get the user's current location on Android?的可能重复也许很明显，但总是值得一提：如果在室内进行测试，那么 GPS 不太可能工作。在任何情况下，找到位置都需要一些时间。 【参考方案1】：

    LocationManager locationManager =
    (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    boolean networkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
    Location location;

    if(networkEnabled)
        longitude=location.getLongitude();
        latitude=location.getLatitude();

在清单文件中添加这些权限：-

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

【讨论】：

如果我已经请求了 FINE LOCATION 的权限，我是否必须再次手动请求 COARSE LOCATION 的权限？还有 NETWORK STATE 的权限呢？它会自动加载还是我必须手动请求？还要做if(networkEnabled) longitude=location.getLongitude(); latitude=location.getLatitude(); ，位置位置不需要设置值吗？没有。试试上面的代码一次。也许它会解决你的问题。此代码缺少某些内容。它实际上并没有以任何方式获得位置。就像建议的那样，会有一个 NullPointerException。在现代 Android 版本中，需要在运行时请求权限。而且它只能通过网络提供商获得不准确的位置。这可能是投反对票的原因。

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