1.问题描述
我的目标是构建一个使用 this workmanager plugin 获取定期位置更新的 Flutter 应用程序。并使用 this location plugin .但是当我的 Workmanager 回调触发时,我无法正确加载 Location 插件。我收到此错误:
MissingPluginException(No implementation found for method getLocation on channel lyokone/location)
所以基本上,问题是当 Workmanager 插件尝试运行 dart 代码时,它不会加载 Location 插件。
2.我研究过的其他资源
我发现其他人面临同样的问题,here , here , 和 here .
据我了解,为这些问题提供的解决方案归结为:创建一个名为 CustomApplication.java 的文件,该文件扩展了 FlutterApplication,并注册了您的插件。然后在 AndoidManifest.xml 文件中注册 CustomApplication.java 文件。
3. 到目前为止我的代码
我试图制作一个实现我需要的功能的最低限度的应用程序:
要准确了解我在每个步骤中所做的工作,请查看此处:https://gitlab.com/tomoerlemans/workmanager_with_location/-/commits/master . (此存储库也可用于快速复制问题)。
相关代码文件如下:
main.dart
import 'package:flutter/material.dart';
import 'package:workmanager/workmanager.dart';
import 'package:location/location.dart';
void main() {
WidgetsFlutterBinding.ensureInitialized();
Workmanager.initialize(callbackDispatcher, isInDebugMode: true);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
onPressed: () {
Workmanager.registerPeriodicTask(
"1", "simpleTask");
},
child: Text("Start workmanager"),
),
RaisedButton(
onPressed: () {
getLocation();
},
child: Text("Get current location"),
),
],
),
),
);
}
}
void callbackDispatcher() {
Workmanager.executeTask((task, inputData) {
print("Native called background task at ${DateTime.now().toString()}");
getLocation();
return Future.value(true);
});
}
void getLocation() async {
LocationData currentLocation;
var location = new Location();
try {
currentLocation = await location.getLocation();
} on Exception catch (e) {
print("Error obtaining location: $e");
currentLocation = null;
}
print("Location altitude: ${currentLocation.altitude}");
print("Location longitude: ${currentLocation.longitude}");
}
pubspec.yaml
name: background_location
description: A new Flutter project.
version: 1.0.0+1
environment:
sdk: ">=2.1.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^0.1.2
workmanager: ^0.2.0
location: ^2.3.5
dev_dependencies:
flutter_test:
sdk: flutter
flutter:
uses-material-design: true
CustomApplication.java
package io.flutter.plugins;
import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import be.tramckrijte.workmanager.WorkmanagerPlugin;
import com.lyokone.location.LocationPlugin;
public class CustomApplication extends FlutterApplication implements PluginRegistry.PluginRegistrantCallback {
@Override
public void onCreate() {
super.onCreate();
WorkmanagerPlugin.setPluginRegistrantCallback(this);
}
@Override
public void registerWith(PluginRegistry registry) {
WorkmanagerPlugin.registerWith(registry.registrarFor("be.tramckrijte.workmanager.WorkmanagerPlugin"));
LocationPlugin.registerWith(registry.registrarFor("com.lyokone.location.LocationPlugin"));
}
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.background_location">
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:name="io.flutter.plugins.CustomApplication"
android:label="background_location"
android:icon="@mipmap/ic_launcher">
<activity
android:name=".MainActivity"
android:launchMode="singleTop"
android:theme="@style/LaunchTheme"
android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
android:hardwareAccelerated="true"
android:windowSoftInputMode="adjustResize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<meta-data
android:name="flutterEmbedding"
android:value="2" />
</application>
</manifest>
最后,我正在运行以下版本的 Dart/Flutter/etc:
Flutter 1.12.13+hotfix.5 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 27321ebbad (10 weeks ago) • 2019-12-10 18:15:01 -0800
Engine • revision 2994f7e1e6
Tools • Dart 2.7.0
最佳答案
我还没有尝试过什么后台位置跟踪,但考虑到你只想从后台进行位置跟踪,那么我认为 workmanager + geolocater会工作。
你应该看到这个项目ha_client它同时使用 workmanager 和 geolocater 来获取坐标
此外,您正在使用的位置包有它自己的后台位置跟踪,这是实验性的 Background Location Updates .
关于android - 如何让 Flutter Workmanager 插件和 Location 插件一起工作,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60262425/