判断当前应用程序状态是在前台还是后台

1

public static boolean isBackground(Context context) {

        Log.d("Nat: isBackground.packageName1", context.getPackageName());

        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();

        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {

            Log.d("Nat: isBackground.processName", appProcess.processName);

            if (appProcess.processName.equals(context.getPackageName())) {

                Log.d("Nat: isBackground.importance", String.valueOf(appProcess.importance));

                if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {

                    Log.i("后台", appProcess.processName);

                    return true;

                }else{

                    Log.i("前台", appProcess.processName);

                    return false;

                }

            }

        }

        return false;

    }

2

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();
            Log.d("Nat: isAppOnForeground.packageName", context.getPackageName());
            for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
                Log.d("Nat: isAppOnForeground.processName", appProcess.processName);
                if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND && appProcess.processName.equals(packageName)) {
                    return true;
                }
            }
            return false;
        }
    }

3

public static boolean isForeground(Context context) {
        Log.d("Nat: isBackground.checkPackageName", context.getPackageName());
        ActivityManager am  = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> runningTasks = am.getRunningTasks(1);
        if (runningTasks != null){
            // The first in the list of RunningTasks is always the foreground task.
            ActivityManager.RunningTaskInfo foregroundTaskInfo = runningTasks.get(0);
            String foregroundTaskPackageName = foregroundTaskInfo .topActivity.getPackageName();
            Log.d("Nat: isBackground.foregroundTaskPackageName", foregroundTaskPackageName);
            if (context.getPackageName().equals(foregroundTaskPackageName)){
                return true;
            }
//            PackageManager pm = context.getPackageManager();
//            PackageInfo foregroundAppPackageInfo = pm.getPackageInfo(foregroundTaskPackageName, 0);
//            String foregroundTaskAppName = foregroundAppPackageInfo.applicationInfo.loadLabel(pm).toString();
        }
        return false;
    }

4