Android中判断语音交友软件源码是处于前台还是后台

简介
有时候我们需要判断语音交友软件源码是处于前台还是后台，这样有利于我们处理一些业务
这里就说下如何判断语音交友软件源码是处于前台还是后台
分别通过RunningTasks，RunningProcess 以及ActivityLifecycleCallbacks

实现
RunningTasks

 private fun getTopApplication() {

        //首先获取到ActivityManager
        val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager

        if (activityManager.getRunningTasks(1) == null) {
            Log.e(TAG, "getForegroundActivity: ")
            return
        }

        var runningTaskInfo = activityManager.getRunningTasks(1)[0]
        if (runningTaskInfo == null) {
            Log.e(TAG, "runningTaskInfo is null")
            return
        }

        runningTaskInfo.topActivity?.let {
            Log.e(TAG, "top application is ${it.packageName}")
        }
    }

getRunningTask方法在5.0以上已经被废弃，只会返回自己和系统的一些不敏感的task，不再返回其他应用的task，用此方法来判断语音交友软件源码是否处于后台仍然有效，但是无法判断其他应用是否位于前台，因为不能再获取信息。

RunningProcess

/**
     * 判断当前应用是否处于前台
     */
    private fun isAppForeground(): Boolean {
        val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        /**
         * 存活的App进程
         */
        var runningAppProcesses = activityManager.runningAppProcesses

        if (runningAppProcesses == null) {
            Log.e(TAG, "runningAppProcesses is null")
            return false
        }

        runningAppProcesses.forEach {
            if (it.processName == packageName && (it.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND)) {
                return true
            }
        }
        return false
    }

 /**
     * 用于判断那个应用是处于前台的
     */
    private fun getForegroundApp(): String? {

        val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        var runningAppProcesses = activityManager.runningAppProcesses
        if (runningAppProcesses.isNullOrEmpty()) {
            return null
        }

        runningAppProcesses.forEach {

            if (it.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND || it.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_VISIBLE) {
                return it.processName
            }
        }

        return null
    }

Android5.0之后已经被废弃。

在语音交友软件源码中，常常需要常驻后台来不间断地获取服务器的消息，就需要把Service设置成START_STICKY，kill后会被重启（等待5s左右）来保证Service常驻后台。如果Service设置了这个属性，这个语音交友软件源码的进程就会被判断为前台。代码表现为

appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND

上述code永远成立，这样就永远无法判断到底那个是前台了。

ActivityLifecycleCallbacks
这里我们对ActivityLifecycleCallbacks的实现类做了一层封装，利用高阶函数，当我们需要去实现那个声明周期的回调的时候，就通过高阶函数来提供回调处理，否则默认不做任何处理

class MyActivityLifecycleCallbacks(
    var onActivityCreatedAction: ((Activity, Bundle?) -> Unit)? = null,
    var onActivityStartedAction: ((Activity) -> Unit)? = null,
    var onActivityResumedAction: ((Activity) -> Unit)? = null,
    var onActivityPausedAction: ((Activity) -> Unit)? = null,
    var onActivityStoppedAction: ((Activity) -> Unit)? = null,
    var onActivitySaveInstanceStateAction: ((Activity, Bundle) -> Unit)? = null,
    var onActivityDestroyedAction: ((Activity) -> Unit)? = null

) : Application.ActivityLifecycleCallbacks {

    private var mCount=0
    override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
        onActivityCreatedAction?.invoke(activity, savedInstanceState)
    }

    override fun onActivityStarted(activity: Activity) {
        mCount++
        onActivityStartedAction?.invoke(activity)
    }

    override fun onActivityResumed(activity: Activity) {
        onActivityResumedAction?.invoke(activity)
    }

    override fun onActivityPaused(activity: Activity) {
        onActivityPausedAction?.invoke(activity)
    }

    override fun onActivityStopped(activity: Activity) {
        mCount--
        onActivityStoppedAction?.invoke(activity)
    }

    override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {
        onActivitySaveInstanceStateAction?.invoke(activity, outState)
    }

    override fun onActivityDestroyed(activity: Activity) {
        onActivityDestroyedAction?.invoke(activity)
    }

    /**
     * 这里我们把mCount的实际数值返回回去
     */
    fun getCount():Int = mCount
}

然后我们在Application的onCreate中进行注册

class LifeApplication : Application() {

    private val TAG = "LifeApplication"

    private val mActivityLifecycleCallbacks by lazy {
        MyActivityLifecycleCallbacks(
            onActivityCreatedAction = { activit, bundle ->
                Log.e(TAG, "onCreate: ")


            },
            onActivityStoppedAction = { activity ->

                Log.e(TAG, "onStop ")

            },
            onActivityDestroyedAction = { activity ->
                Log.e(TAG, "onDestroy")

            })
    }

    override fun onCreate() {
        super.onCreate()
        instance = this
        //注册生命周期回调事件
        registerActivityLifecycleCallbacks(mActivityLifecycleCallbacks)
    }

    /**
     * 用于判断当前进程是否处于前台
     */
    fun isForegroundMethod(): Boolean = mActivityLifecycleCallbacks.getCount() > 0


    companion object{
        private  var  instance :LifeApplication?= null
        fun getInstance () = instance!!
    }

当我们不管是点击Back键还是Home键都会回调到onStop方法，我们在onStart和onStop中分别对mCount值做了加减
这样我们可以通过该数值来判断当前语音交友软件源码是否处于前台还是后台

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原文链接：https://www.jianshu.com/p/a326ee3c582e