Android如何判断是否在后台运行

创建一个BaseActivity,然后在onStop中判断是否在后台，设置标志，然后在onResume中根据这个标志来执行相应的操作，让所有的Activity继承它，判断是否在后台的代码为

public boolean isAppOnForeground() {

                ActivityManager activityManager = (ActivityManager) getApplicationContext()

                                .getSystemService(Context.ACTIVITY_SERVICE);

                String packageName = getApplicationContext().getPackageName();

                List<RunningAppProcessInfo> appProcesses = activityManager

                                .getRunningAppProcesses();

                if (appProcesses == null)

                        return false;

                for (RunningAppProcessInfo appProcess : appProcesses) {

                        if (appProcess.processName.equals(packageName)

                                        && appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {

                                return true;

                        }

                }

                return false;

        }