问题描述
我在我的应用程序中实现了一个自定义应用程序类,它在应用程序启动之前处理更新应用程序主题。
我的应用类是这样的:
应用程序.kt
package com.th3pl4gu3.mes.ui
.....
class MesApplication : Application() {
companion object {
@Volatile
private var INSTANCE: MesApplication? = null
fun getInstance() =
INSTANCE ?: synchronized(this) {
INSTANCE
?: MesApplication().also { INSTANCE = it }
}
}
override fun onCreate() {
super.onCreate()
// Assigns 'this' to the singleton object
INSTANCE = this
// Updates the application's theme
updateAppTheme()
// Start a network callback to monitor internet connection
startNetworkCallback()
}
private fun startNetworkCallback(){
try{
val cm = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
val builder = NetworkRequest.Builder()
cm.registerNetworkCallback(builder.build(),object: ConnectivityManager.NetworkCallback(){
override fun onAvailable(network: Network) {
super.onAvailable(network)
Log.v("INTERNET_TEST","AC: Network Available")
Global.isNetworkConnected = true
}
override fun onLost(network: Network) {
super.onLost(network)
Log.v("INTERNET_TEST","AC: Network Lost")
Global.isNetworkConnected = false
}
})
Global.isNetworkConnected = false
}catch (e: Exception){
Global.isNetworkConnected = false
}
}
}
但是,从文档中,他们建议取消注册此回调,但 Application 类生命周期没有任何 onPause 或 onDestroy 函数。
是否有任何适当的方法可以取消注册此回调以不导致任何内存泄漏?
也可以随意提出任何替代方案,以防我编码错误
解决方法
在这种情况下,您可以使用 ActivityLifecycleCallbacks
来检测您的任何 Activity 是否在 Foreground
中?
ActivityLiveCycleListener
class ActivityLiveCycleListener(private val appStateListener: AppStateListener) : Application.ActivityLifecycleCallbacks {
companion object {
var foregroundActivities = 0
}
override fun onActivityPaused(p0: Activity) {
}
override fun onActivityStarted(p0: Activity) {
if(foregroundActivities == 0){
appStateListener.onAppForeGround()
}
foregroundActivities++
}
override fun onActivityDestroyed(p0: Activity) {
}
override fun onActivitySaveInstanceState(p0: Activity,p1: Bundle) {
}
override fun onActivityStopped(p0: Activity) {
foregroundActivities--
if(foregroundActivities == 0){
appStateListener.onAppBackground()
}
}
override fun onActivityCreated(p0: Activity,p1: Bundle?) {
}
override fun onActivityResumed(p0: Activity) {
}
}
并且你的界面可以有两种方法来指示背景/前景状态
interface AppStateListener{
fun onAppForeGround()
fun onAppBackground()
}
现在在应用程序 onCreate()
中,注册到 ActivityLifeCycleListener
override fun onCreate(){
registerActivityLifecycleCallbacks(ActivityLiveCycleListener(object : AppStateListener{
override fun onAppForeGround() {
//start network listener
}
override fun onAppBackground() {
//remove network listener
}
}))
}