TL;DR 如何让 Android 传感器永久运行/活动/注册我的应用程序，即使我关闭它？
客观的：
我正在制作一个 Flutter 应用程序，使用以下方法来计算您的步数计步器 https://pub.dev/packages/pedometer包裹，
它使用内置传感器TYPE_STEP_COUNTER安卓系统的 https://developer.android.com/reference/android/hardware/Sensor#TYPE_STEP_COUNTER,
which 返回自上次启动以来执行的步骤数 (iOS)。在 Android 上，安装应用程序之前执行的任何步骤均不计算在内。 https://pub.dev/packages/pedometer#:%7E:text=The%20step%20count%20represents%20the%20number%20of%20steps%20taken%20since%20the%20last%20system%20boot.%20On%20Android%2C%20any%20steps%20taken%20before%20installing%20the%20application%20will%20not%20be%20counted.
我是如何实现的：
- 当应用程序在前台主动运行时，每个步骤都会导致
A
myStepCount增加 1。
- 在所有其他情况下（手机锁定，进入主屏幕，关闭应用程序......）, 安卓
TYPE_STEP_COUNTER sensor 应该
仍在运行在后台，一旦我再次打开我的应用程序，
新与新的区别stepCount和最后保存的stepCount（已保存
使用shared_prefs）将被计算并添加到myStepCount.
重要的：
The TYPE_STEP_COUNTER传感器必须在后台永久运行/保持注册 https://developer.android.com/reference/android/hardware/Sensor#:%7E:text=If%20you%20want,is%20not%20activated.，即使在我锁定手机、转到主屏幕或关闭应用程序之后...
观察结果：
- 在我的三星 Galaxy A02s 上，我的应用程序运行得非常好，正如它预期的那样
（如上所述）。那是因为在那部手机上我也有
安装了 Google Fit 应用程序，该应用程序 24/7 跟踪您的步数（因此
TYPE_STEP_COUNTER传感器已永久注册）。
- 在我的 Samsung Galaxy S7 上，我的应用程序不起作用正如它应该的那样。
myStepCount当我在应用程序运行时采取步骤时，会增加
在前台运行。但应用程序关闭时采取的步骤
将要NOT被添加到myStepCount一旦我再次打开应用程序。
注意：我的这款手机上没有任何其他计步应用程序（例如 Google Fit）。
结论：
我需要找到一种方法来注册TYPE_STEP_COUNTER来自我的 Flutter 应用程序的传感器，即使在我关闭应用程序后也保持其注册状态。
2 尝试过（但不成功）的解决方案：
第一次尝试：
从我的 Flutter 代码中调用本机 Android 代码来注册传感器
这是我的main.dart文件（为了简单起见，省略了不重要的部分）：
void main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(App());
}
class App extends StatefulWidget {
@override
_AppState createState() => _AppState();
}
class _AppState extends State<App> with WidgetsBindingObserver {
@override
void initState() {
super.initState();
if (Platform.isAndroid) {
_activateStepCounterSensor();
} else if (Platform.isIOS) {
//TODO check if anything is needed to to here
}
}
void _activateStepCounterSensor() async {
MethodChannel _stepCounterChannel = MethodChannel('com.cedricds.wanderapp/stepCounter'); //convention
dynamic result = await _stepCounterChannel.invokeMethod('activateStepCounterSensor');
switch (result) {
case "success":
//The following line gets printed when I run the flutter app on my Samsung Galaxy S7:
print('_activateStepCounterSensor(): successfully registered step counter sensor for android');
break;
case "error":
print('_activateStepCounterSensor(): failed to register step counter sensor (not available) for android');
//TODO display errorpage (because app is completely useless in this case)
break;
default:
print('_activateStepCounterSensor(): unknown result: $result');
break;
}
}
//build() and other lifecycle-methods and helper methods: not important for this question
}
这是我的MainActivity.kt file:
package com.cedricds.wanderapp
import android.content.Context
import android.hardware.Sensor
import android.hardware.SensorEvent
import android.hardware.SensorEventListener
import android.hardware.SensorManager
import android.util.Log
import android.widget.Toast
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel
class MainActivity2: FlutterActivity(), SensorEventListener {
private val STEP_COUNTER_CHANNEL = "com.cedricds.wanderapp/stepCounter";
private lateinit var channel: MethodChannel
override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
super.configureFlutterEngine(flutterEngine)
channel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, STEP_COUNTER_CHANNEL)
channel.setMethodCallHandler { call, result ->
when(call.method){ //this is like switch-case statement in Java
"activateStepCounterSensor" -> {
activateStepCounterSensor(result)
}
}
}
}
private var sensorManager : SensorManager?=null
private var sensor: Sensor ?= null
private fun activateStepCounterSensor(result: MethodChannel.Result) {
//This line gets printed when I run the flutter app, so the method gets called successfully:
Log.d("Android", "Native Android: activateStepCounterSensor()")
sensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
sensor = sensorManager?.getDefaultSensor(Sensor.TYPE_STEP_COUNTER)
if (sensor == null) {
Toast.makeText(this, "missing hardware.", Toast.LENGTH_LONG).show()
result.error("error", "error", "error")
} else {
sensorManager?.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL)
//This line gets printed:
Log.d("Android", "Native Android: registered TYPE_STEP_COUNTER")
//and never unregister that listener
result.success("success")
}
}
override fun onSensorChanged(p0: SensorEvent?) {}
override fun onAccuracyChanged(p0: Sensor?, p1: Int) {}
}
尽管为数不多print(...) and Log.d(...)按预期在控制台中打印，该应用程序无法按我预期的方式工作。当我退出应用程序时，步行例如 50 步，然后再次打开应用程序，这 50 步就消失了。传感器似乎在某处未注册。
第二次尝试：
通过删除修改计步器包的代码unregisterListener(...)：
我对文件所做的唯一更改是 2Log.d(...)语句，更重要的是，注释掉特定的代码行。
修改的SensorStreamHandler.kt来自计步器包：
package com.example.pedometer
import android.content.Context
import android.hardware.Sensor
import android.hardware.SensorEventListener
import android.hardware.SensorManager
import android.os.Looper
import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.EventChannel
import android.os.Handler
import android.util.Log
class SensorStreamHandler() : EventChannel.StreamHandler {
private var sensorEventListener: SensorEventListener? = null
private var sensorManager: SensorManager? = null
private var sensor: Sensor? = null
private lateinit var context: Context
private lateinit var sensorName: String
private lateinit var flutterPluginBinding: FlutterPlugin.FlutterPluginBinding
constructor(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding, sensorType: Int) : this() {
this.context = flutterPluginBinding.applicationContext
this.sensorName = if (sensorType == Sensor.TYPE_STEP_COUNTER) "StepCount" else "StepDetection"
sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as SensorManager
sensor = sensorManager!!.getDefaultSensor(sensorType)
this.flutterPluginBinding = flutterPluginBinding
}
override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
Log.d("Pedometer", "Native Android: onListen()")
if (sensor == null) {
events!!.error("1", "$sensorName not available",
"$sensorName is not available on this device");
} else {
sensorEventListener = sensorEventListener(events!!);
sensorManager!!.registerListener(sensorEventListener, sensor, SensorManager.SENSOR_DELAY_NORMAL);
}
}
override fun onCancel(arguments: Any?) {
Log.d("Pedometer", "Native Android: onCancel()")
//The only change I did: commenting out the following line:
// sensorManager!!.unregisterListener(sensorEventListener);
}
}
这也没有解决我的问题。因此，如果有人知道如何在我的 flutter 应用程序中永久注册 TYPE_STEP_COUNTER 传感器，请告诉我。
