TL;DR 我怎样才能让 Android 传感器为我的应用程序永久运行/激活/注册,即使我关闭它?
目标:
我正在制作一个 Flutter 应用程序,它使用计步器包计算您的步数,
该包使用Android的内置传感器TYPE_STEP_COUNTER
,
它返回自上次启动 (iOS) 以来采取的步数。在 Android 上,安装应用程序之前采取的任何步骤都不会计算在内。
我是如何实现的:
- 当应用程序在前台主动运行时,每一步都会导致 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...),android
TYPE_STEP_COUNTER
传感器仍应在后台运行stepCount
,一旦我再次打开我的应用程序,新的和上次保存的区别stepCount
(保存使用 shared_prefs) 将被计算并添加到myStepCount
.
重要提示:
传感器TYPE_STEP_COUNTER
必须在后台永久运行/保持注册,即使在我锁定手机、转到主屏幕或关闭应用程序后...
观察:
- 在我的三星 Galaxy A02s 上,我的应用程序运行良好,正如它应该的那样(如上所述)。那是因为在那部手机上我还安装了 Google Fit 应用程序,它可以 24/7 跟踪您的步数(因此
TYPE_STEP_COUNTER
传感器被永久注册)。 - 在我的三星 Galaxy S7 上,我的应用程序无法正常运行。
myStepCount
当我在应用程序在前台运行时采取措施时会增加。但是,一旦我再次打开应用程序,将不会添加应用程序关闭时采取的步骤。注意:我在这款手机上没有任何其他计步应用,例如 Google Fit。myStepCount
结论:
我需要找到一种方法TYPE_STEP_COUNTER
从我的 Flutter 应用程序中注册传感器,并且即使在我关闭应用程序后也保持注册状态。
2 尝试(但不成功)的解决方案:
第一次尝试:
从我的 Flutter 代码中调用原生 Android 代码来注册传感器
这是我的main.dart
文件(为简单起见,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
文件:
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) {}
}
尽管数量很少print(...)
并且Log.d(...)
按预期在控制台中打印,但该应用程序无法按我预期的方式运行。当我退出应用程序时,例如走 50 步,然后再次打开应用程序,那 50 步就不见了。似乎传感器在某处未注册。
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(...)
条语句,更重要的是,注释掉了特定的代码行。
SensorStreamHandler.kt
从计步器包修改:
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,如果有人知道我如何在我的颤振应用程序中永久注册 TYPE_STEP_COUNTER 传感器,请告诉我。