Android判断App是否在前台运行

//    public static final int IMPORTANCE_BACKGROUND = 400//后台
//    public static final int IMPORTANCE_EMPTY = 500//空进程
//    public static final int IMPORTANCE_FOREGROUND = 100//在屏幕最前端、可获取到焦点 可理解为Activity生命周期的OnResume();
//    public static final int IMPORTANCE_SERVICE = 300//在服务中
//    public static final int IMPORTANCE_VISIBLE = 200//在屏幕前端、获取不到焦点可理解为Activity生命周期的OnStart();
    //当前应用是否处于前台
    private boolean isRuning(String packageName) {
        if (AppContext != null) {
            ActivityManager activityManager = (ActivityManager) AppContext.getSystemService(Context.ACTIVITY_SERVICE);
            List processes = activityManager.getRunningAppProcesses();
            for (ActivityManager.RunningAppProcessInfo processInfo: processes) {
                if (processInfo.processName.equals(packageName)) {
                    if (processInfo.importance <500) {
                        return true;
                    }
                }
            }
        }
        return false;
    }