Android前后台判断总是前台问题解决办法

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.

详细代码：

class ForegroundCheckTask extends AsyncTask<Context, Void, Boolean> {    @Override    protected Boolean doInBackground(Context... params) {        final Context context = params[0].getApplicationContext();        return isAppOnForeground(context);    }    private boolean isAppOnForeground(Context context) {        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();        if (appProcesses == null) {            return false;        }        final String packageName = context.getPackageName();        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {            if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND && appProcess.processName.equals(packageName)) {                return true;            }        }        return false;    }}