android 判断当前应用是否在后台运行时得到的结果总是IMPORTANCE_FOREGROUND

Question

我在servie或者receiver 中做测试，已经退出了应用的所有的activity，判断应用的状态，取到当前应用包名的RunningAppProcessInfo，但是它的importance值时100 ，也就是IMPORTANCE_FOREGROUND。迷惑了～

Answer 1

也许这不是你程序的问题，是判断应用当前状态的方法有问题

You can detect currently foreground/background application with ActivityManager.getRunningAppProcesses()which returns a list of RunningAppProcessInfo records. To determine if your application is on the foreground checkRunningAppProcessInfo.importance fieldfor equality to RunningAppProcessInfo.IMPORTANCE_FOREGROUND whileRunningAppProcessInfo.processName is equal to your application package name.
Also if you call ActivityManager.getRunningAppProcesses() from your application UI thread it will return importance IMPORTANCE_FOREGROUND for your task no matter whether it is actually in the foreground or not. Call it in thebackground thread(for example via AsyncTask) and it will return correct results.
详见Checking if an Android application is running in the background