GPS 位置不会显示在手机上

Question

我正试图从GPS中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 Permissionn");
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("Hellon");
}

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

我还在android清单中添加了精细定位和粗略定位的权限。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

还有即使我在模拟器上运行它，当我移动笔记本电脑时，位置也不会更新，为什么？

Answer 1

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

如果您不允许ACCESS_FINE_LOCATION和ACCESS_COARSE_LOCATION，则会导致错误，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，如果权限未被授予，则此代码会询问权限。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。我用一个物理设备测试了这个代码，它似乎可以正常工作。