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java - GPS位置不会显示在手机上

问题描述

我正在尝试从 GPS 获取位置并将其显示在屏幕上，到目前为止我有以下代码：

public class MainActivity extends AppCompatActivity implements LocationListener {

    EditText el;
    TextView output;

    LocationManager lm;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        el = (EditText) findViewById(R.id.editText);
        output = (TextView) findViewById(R.id.textView2);
        output.setMovementMethod(new ScrollingMovementMethod());
        output.setText("");

        LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        output.append("Start");
        if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

            //ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION}, 1);

             output.append("Initially Failed to Grand Permission\n");
             return;
        }
        output.append("\nOutside Permission controle");

        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
        output.append("\nYoo");

    }

    public void send(View v) {
        MessageSender messageSender = new MessageSender();
        messageSender.execute(el.getText().toString());
        output.append("Hello\n");

    }


    @Override
    public void onLocationChanged(@NonNull Location location) {
        output.append("Inside location function");
        output.append(String.valueOf(location.getLongitude()));
    }
}

我还在 android 清单中添加了精细位置和粗略位置的权限。我错过了什么？

我正在使用三星 Galaxy S10

注意 当我在android studio上使用模拟器时，它会显示位置，但是当我使用usb调试器并在我的android设备上运行它时，它不会显示位置

另外 ，即使我在模拟器上运行它，移动笔记本电脑时位置也不会更新，为什么？

标签： javaandroidandroid-emulator

解决方案

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);

如果您不允许ACCESS_FINE_LOCATION，则会导致错误，ACCESS_COARSE_LOCATION因此您必须询问这些权限。你可以这样做：

if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ||
            ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION}, 1);
    } else {
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
    }

请注意，&&已更改为||。基本上，如果未授予权限，此代码会询问权限。如果已授予权限，请调用locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);

如果没有授予权限怎么办？您需要等到授予权限后才能调用requestLocationUpdates. 在授予权限后调用此方法。

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    return;
                }
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
            return;
        }
    }
}

将此方法添加到活动中。我用物理设备测试了这段代码，它似乎可以正常工作。

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