我在pub.dev上找到了这个软件包，它对我来说很好用，而且很容易使用
https://pub.dev/packages/move_to_background

03.2020更新

正如@user1717750所写的-dart代码保持不变，所以它是：

var _androidAppRetain = MethodChannel("android_app_retain");

@override
Widget build(BuildContext context) {
return WillPopScope(
  onWillPop: () {
    if (Platform.isAndroid) {
      if (Navigator.of(context).canPop()) {
        return Future.value(true);
      } else {
        _androidAppRetain.invokeMethod("sendToBackground");
        return Future.value(false);
      }
    } else {
      return Future.value(true);
    }
  },
  child: Scaffold(
    ...
  ),
);
}

字符串
MainActivity（）中的代码应该如下所示：

class MainActivity: FlutterActivity() {

override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
    GeneratedPluginRegistrant.registerWith(flutterEngine);

    MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "android_app_retain").apply {
        setMethodCallHandler { method, result ->
            if (method.method == "sendToBackground") {
                moveTaskToBack(true)
            }
        }
    }
}
}

型

从这里：https://medium.com/stuart-engineering/%EF%B8%8F-the-tricky-task-of-keeping-flutter-running-on-android-2d51bbc60882
模板代码：

class MainActivity : FlutterActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        GeneratedPluginRegistrant.registerWith(this)

        MethodChannel(flutterView, "android_app_retain").apply {
            setMethodCallHandler { method, result ->
                if (method.method == "sendToBackground") {
                    moveTaskToBack(true)
                }
            }
        }
    }
}

字符串
您的 dart 代码：

Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: () {
        if (Platform.isAndroid) {
          if (Navigator.of(context).canPop()) {
            return Future.value(true);
          } else {
            _androidAppRetain.invokeMethod("sendToBackground");
            return Future.value(false);
          }
        } else {
          return Future.value(true);
        }
      },
      child: Scaffold(
        drawer: MainDrawer(),
        body: Stack(
          children: <Widget>[
            GoogleMap(),
          ],
        ),
      ),
    );
  }

型
作者：Sergi Castellsagué Millán

07.2023更新

@Muscler回答：
平台代码（Kotlin）再次更改：

import androidx.annotation.NonNull
    import io.flutter.embedding.android.FlutterActivity
    import io.flutter.embedding.engine.FlutterEngine
    import io.flutter.plugin.common.MethodChannel

    class MainActivity: FlutterActivity() {
        override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
            super.configureFlutterEngine(flutterEngine)

            MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "android_app_retain").apply {
                setMethodCallHandler { method, result ->
                    if (method.method == "sendToBackground") {
                        moveTaskToBack(true)
                    }
                }
            }
        }
   }

字符串
如果它再次改变，你应该看看flutter文档：https://docs.flutter.dev/platform-integration/platform-channels?tab=android-channel-kotlin-tab
dart代码还是一样的，所以是：

var _androidAppRetain = MethodChannel("android_app_retain");

@override
Widget build(BuildContext context) {
return WillPopScope(
  onWillPop: () {
    if (Platform.isAndroid) {
      if (Navigator.of(context).canPop()) {
        return Future.value(true);
      } else {
        _androidAppRetain.invokeMethod("sendToBackground");
        return Future.value(false);
      }
    } else {
      return Future.value(true);
    }
  },
  child: Scaffold(
    ...
  ),
);
}

型