判断应用是否处于前台

private boolean isforeground() {
    activitymanager activitymanager = (activitymanager) getsystemservice(context.activity_service);
    list<activitymanager.runningappprocessinfo> processes = activitymanager.getrunningappprocesses();
    
    if (processes == null || processes.isempty()) {
        return false;
    }
    
    for (activitymanager.runningappprocessinfo info : processes) {
        if (info.processname.equals(getpackagename()) &&
                info.importance == activitymanager.runningappprocessinfo.importance_foreground) {
            return true;
        }
    }
    return false;
}