如何使用Java

Question

我正在尝试使用Flutter应用程序的本机代码来获取当前位置。

实现类似于Google Maps的功能似乎更可行，在该应用中，应用程序询问用户是否希望打开位置，如果他们说确定，则位置会自动打开。我已经能够成功完成此操作，但我也想将当前位置返回到颤振端。现在，我从onActivityResult（）获取用户操作，然后在resultCode == RESULT_OK的情况下运行getLastLocation（）方法。但是，我希望颤振结束要等到获得当前位置。我尝试使用锁定机制，但这会导致应用程序冻结。目前，我只有使用Thread.sleep（long millis）的幼稚实现，直到获得肯定的结果为止，然后将结果返回到flutter。

这是打开位置信息的代码：

private void turnLocationOn(Context context) {
  GoogleApiClient googleApiClient = new GoogleApiClient.Builder(context)
          .addApi(LocationServices.API).build();
  googleApiClient.connect();

  LocationRequest locationRequest = LocationRequest.create();
  locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
  locationRequest.setInterval(10000);
  locationRequest.setFastestInterval(10000 / 2);

  LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()
          .addLocationRequest(locationRequest);
  builder.setAlwaysShow(true);

  Task<LocationSettingsResponse> result = LocationServices.getSettingsClient(this)
          .checkLocationSettings(builder.build());
    result.addOnCompleteListener(new OnCompleteListener<LocationSettingsResponse>() {
        @Override
        public void onComplete(@NonNull Task<LocationSettingsResponse> task) {
            try {
                LocationSettingsResponse response =
                        task.getResult(ApiException.class);
            } catch (ApiException ex) {
                switch (ex.getStatusCode()) {
                    case LocationSettingsStatusCodes
                            .RESOLUTION_REQUIRED:
                        try {
                            ResolvableApiException resolvableApiException =
                                    (ResolvableApiException) ex;
                            resolvableApiException
                                    .startResolutionForResult(MainActivity.this,
                                            LOCATION_SETTINGS_REQUEST);
                        } catch (IntentSender.SendIntentException e) {
                              e.printStackTrace();
                        }
                        break;
                    case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                        break;
                }
            }
        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == LOCATION_SETTINGS_REQUEST) {
        if (resultCode == RESULT_OK)
        {
            Log.i(TAG, "User turned on location");
            callResult = true;
        } else if (resultCode == RESULT_CANCELED) {
            Log.i(TAG, "User declined location setting request");
            callResult = false;
           // setCallResult(false);
        }
    }
}

这是设置当前位置的方法。它是LocationListener的实现：

@Override
public void onLocationChanged(Location location) {
    callResult = true;
    currLocation = location.getLatitude() + ", " + location.getLongitude();
}

这是Method通道，可将结果返回到flutter

new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
        new MethodChannel.MethodCallHandler() {
            @Override
            public void onMethodCall(MethodCall methodCall, MethodChannel.Result result) {
                if (methodCall.method.equals("getCurrentLocation")) {
                    turnLocationOn(MainActivity.this);
                    while (!callResult) {
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    result.success(currLocation);
                } else {
                    result.notImplemented();
                }
            }
        });

...这是从颤动的一端

final String result = await platform.invokeMethod('getCurrentLocation');
resultFromCall = "SUCCESS: $result";
debugPrint(resultFromCall);