我想让我的 map 在打开 MapActivity 时聚焦在我的当前位置。 我对特定行有问题:

mMap.setMyLocationEnabled(true);  

Call requires permission which may be rejected by user:code should explicitly check to see if permission is availabe with ('checkPermission') or explicitly handle with potential 'SecurityException'.

我该如何解决这个问题？ 我在搜索此问题时阅读了一些内容，但找不到有用的内容。

完整代码:

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private static final String FIREBASE_URL="https://haerev.firebaseio.com/";
private Firebase firebaseRef;
private GoogleMap mMap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps2);
    Firebase.setAndroidContext(this);
    firebaseRef = new Firebase(FIREBASE_URL);


    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    setUpMapIfNeeded();

}

private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        mMap.setMyLocationEnabled(true);
        // Check if we were successful in obtaining the map.
        if (mMap != null) {


            mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {

                @Override
                public void onMyLocationChange(Location arg0) {
                    // TODO Auto-generated method stub

                    mMap.addMarker(new MarkerOptions().position(new LatLng(arg0.getLatitude(), arg0.getLongitude())).title("It's Me!"));
                }
            });

        }
    }
}

阅读了一些评论后，阅读本期:http://developer.android.com/training/permissions/requesting.html

我添加了这些行:

 private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();

        if (ContextCompat.checkSelfPermission(MapsActivity.this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {


            if (ActivityCompat.shouldShowRequestPermissionRationale(MapsActivity.this,
                    Manifest.permission.ACCESS_FINE_LOCATION)) {

               checkSelfPermission("You have to accept to enjoy the most hings in this app");
            } else {


                ActivityCompat.requestPermissions(MapsActivity.this,
                        new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                        MY_PERMISSION_REQUEST_ACCESS_FINE_LOCATION);

            }
        }

        mMap.setMyLocationEnabled(true);
        // Check if we were successful in obtaining the map.
        if (mMap != null) {


            mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {

                @Override
                public void onMyLocationChange(Location arg0) {
                    // TODO Auto-generated method stub

                    mMap.addMarker(new MarkerOptions().position(new LatLng(arg0.getLatitude(), arg0.getLongitude())).title("It's Me!"));
                }
            });

        }
    }
}

但是现在我遇到了一个新问题。它无法识别该行

"MY_PERMISSION_REQUEST_ACCESS_FINE_LOCATION".

我想我用错了。 我应该如何使用它？

最佳答案

在网络上进行大量研究后，这就是对我有用的:

 private void setUpMapIfNeeded() {
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            mMap.setMyLocationEnabled(true);
        } else {
            Toast.makeText(MapsActivity.this, "You have to accept to enjoy all app's services!", Toast.LENGTH_LONG).show();
            if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                    == PackageManager.PERMISSION_GRANTED) {
                mMap.setMyLocationEnabled(true);
            }
        }

        if (mMap != null) {


            mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {

                @Override
                public void onMyLocationChange(Location arg0) {
                    // TODO Auto-generated method stub

                    CameraUpdate center= CameraUpdateFactory.newLatLng(new LatLng(arg0.getLatitude(), arg0.getLongitude()));
                    CameraUpdate zoom=CameraUpdateFactory.zoomTo(12);

                    mMap.moveCamera(center);
                    mMap.animateCamera(zoom);
                }
            });

        }
    }
}

关于java - 如何解决 setMyLocationEnabled 权限要求？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36091197/