Android-通过GPS错误获取国家/地区

你好：）

我在onStart（）中创建了一些代码；方法来确保用户启用了GPS，这样我就可以知道他现在在哪个国家。如果GPS被禁用，则应显示一个警报对话框，提示用户在使用应用程序之前启用GPS

出于某种原因，似乎整段代码都无法正常工作。我已经禁用了GPS，但什么都没有发生，没有对话，什么都没有。为什么会这样

这是我的密码：

    @Override
protected void onStart() {
    super.onStart();

    LocationManager locationManager =
            (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    final boolean gpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

    Location loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    Geocoder code = new Geocoder(TipCalculatorActivity.this);
    try {
        Address adr = (Address) code.getFromLocation(loc.getLatitude(), loc.getLongitude(), 1);
        CountryName = adr.getCountryCode();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    if (!gpsEnabled) {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("This application requires GPS connectivity to determine your current country, and deliver you accurate tip ratings. Do you wish to turn GPS on?")
               .setCancelable(false)
               .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                   public void onClick(DialogInterface dialog, int id) {
                        TipCalculatorActivity.this.enableLocationSettings();
                   }
               })
               .setNegativeButton("No", new DialogInterface.OnClickListener() {
                   public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                        TipCalculatorActivity.this.finish();
                        System.exit(1);
                   }
               });
        AlertDialog alert = builder.create();
        alert.show();
    }
}

private void enableLocationSettings() {
    Intent settingsIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
    startActivity(settingsIntent);
}

非常感谢您的帮助：）

位置loc=位置管理器 .getLastKnownLocation（LocationManager.GPS\U提供商）

在您的情况下，Is可能返回null，因为您的手机没有缓存位置

所以把你的代码改成

if (loc != null) {
    Geocoder code = new Geocoder(AbcActivity.this);
    try {
        Address adr = (Address) code.getFromLocation(loc.getLatitude(), loc.getLongitude(), 1);
        // CountryName = adr.getCountryCode();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

如果需要查询当前位置，则需要打开活动数据连接或GPS。 下面的代码片段将对您有所帮助

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

public class ShowLocationActivity extends Activity implements LocationListener {
    private TextView latituteField;
    private TextView longitudeField;
    private LocationManager locationManager;
    private String provider;


/** Called when the activity is first created. */

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        latituteField = (TextView) findViewById(R.id.TextView02);
        longitudeField = (TextView) findViewById(R.id.TextView04);

        // 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);
        Location location = locationManager.getLastKnownLocation(provider);

        // Initialize the location fields
        if (location != null) {
            System.out.println("Provider " + provider + " has been selected.");
            int lat = (int) (location.getLatitude());
            int lng = (int) (location.getLongitude());
            latituteField.setText(String.valueOf(lat));
            longitudeField.setText(String.valueOf(lng));
        } else {
            latituteField.setText("Provider not available");
            longitudeField.setText("Provider not available");
        }
    }

    /* Request updates at startup */
    @Override
    protected void onResume() {
        super.onResume();
        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());
        latituteField.setText(String.valueOf(lat));
        longitudeField.setText(String.valueOf(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();
    }
}

最后，确保您添加了以下权限

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

gps禁用时是否显示警报对话框？如果loc为空，我该怎么办？是否有一些代码可以在没有缓存的情况下获取当前位置？我似乎在onPause（）和onResume（）方法中发现了一个错误，告诉我“this”不适用，它需要一个locationListener。我在所有onLocationChanged、onStatusChanged、onProviderEnabled和onProviderDisabled方法中都遇到了一个bug。它告诉我删除@override。。。这些方法不应该在侦听器中吗？