Flutter 后台持续定位 高德

Flutter 可以通过使用高德地图 SDK 实现后台持续定位。以下是一些概述步骤：

1. 在 pubspec.yaml 文件中添加高德地图 SDK 的依赖。

2. 在 AndroidManifest.xml 文件中添加定位权限和服务声明。

3. 在 Info.plist 文件中添加定位权限请求。

4. 在 Flutter 中使用 MethodChannel 调用原生代码实现后台定位。

下面是一个示例代码：

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class LocationPage extends StatefulWidget {
  @override
  _LocationPageState createState() => _LocationPageState();
}

class _LocationPageState extends State<LocationPage> {
  static const platform = const MethodChannel('com.example.location');

  String location = '';

  Future<void> _getLocation() async {
    String result;
    try {
      result = await platform.invokeMethod('getLocation');
    } on PlatformException catch (e) {
      print(e);
    }

    setState(() {
      location = result;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Location'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('Location: $location'),
            RaisedButton(
              child: Text('Get Location'),
              onPressed: _getLocation,
            ),
          ],
        ),
      ),
    );
  }
}

在原生代码中，可以使用高德地图 SDK 提供的 AMapLocationClient 类实现后台定位。以下是一个示例代码：

public class LocationPlugin implements MethodCallHandler {
    private AMapLocationClient locationClient;
    private AMapLocationListener locationListener;

    public LocationPlugin(Context context) {
        locationClient = new AMapLocationClient(context);
        locationClient.setInterval(2000);
        locationClient.setLocationOption(getDefaultOption());
        locationListener = new AMapLocationListener() {
            @Override
            public void onLocationChanged(AMapLocation aMapLocation) {
                if (aMapLocation != null) {
                    String location = String.format("%f,%f", aMapLocation.getLongitude(), aMapLocation.getLatitude());
                    sendLocationUpdate(location);
                }
            }
        };
        locationClient.setLocationListener(locationListener);
    }

    private AMapLocationClientOption getDefaultOption() {
        AMapLocationClientOption option = new AMapLocationClientOption();
        option.setLocationMode(AMapLocationClientOption.AMapLocationMode.Hight_Accuracy);
        option.setInterval(2000);
        option.setNeedAddress(false);
        option.setWifiScan(true);
        option.setKillProcess(false);
        option.setSensorEnable(false);
        option.setLocationCacheEnable(false);
        return option;
    }

    private void sendLocationUpdate(String location) {
        Intent intent = new Intent("com.example.location");
        intent.putExtra("location", location);
        LocalBroadcastManager.getInstance(context).sendBroadcast(intent);
    }

    @Override
    public void onMethodCall(MethodCall call, Result result) {
        switch (call.method) {
            case "getLocation":
                locationClient.startLocation();
                break;
            default:
                result.notImplemented();
                break;
        }
    }
}

在 AndroidManifest.xml 文件中，需要添加以下权限和服务声明：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
<service android:name="com.example.location.LocationService" />

在 LocationService 类中，需要创建一个 LocationPlugin 对象，并在 onStartCommand 方法中启动后台定位：

public class LocationService extends Service {
    private LocationPlugin locationPlugin;

    @Override
    public void onCreate() {
        super.onCreate();
        locationPlugin = new LocationPlugin(this);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        locationPlugin.startLocation();
        return START_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}