override def preStart() {    webUi = new WorkerWebUI(this, workDir, Some(webUiPort))    webUi.bind()  //创建并绑定UI    registerWithMaster()  //注册到Master}def tryRegisterAllMasters() {    for (masterUrl <- masterUrls) {    logInfo("Connecting to master " + masterUrl + "...")    val actor = context.actorSelection(Master.toAkkaUrl(masterUrl))    actor ! RegisterWorker(workerId, host, port, cores, memory, webUi.boundPort, publicAddress)    }}