UM2000型无绝缘轨道电路在站内无岔区段,当邻线同频时,轨道电路极限长度为()。
A. 450m
B. 800m
C. 1000m
D. 1200m
查看答案
高压负荷开关是一种具有一定分断能力和接通能力的高压开关设备。
A. 正确
B. 错误
火势十分强烈,正在蔓延,切勿试图扑灭,应立即逃出火场,打电话召消防队救火。
A. 正确
B. 错误
Your web application requires the adding and deleting of many session attributes during a complex usecase. A bug report has come in that indicates that an important session attribute is being deleted too soonand a NullPointerException is being thrown several interactions after the fact. You have decided to create asession event listener that will log when attributes are being deleted so you can track down when theattribute is erroneously being deleted. Which listener class will accomplish this debugging goal?()
A. Create an HttpSessionAttributeListener class and implement the attributeDeleted method and log the attribute name using the getName method on the event object.
B. Create an HttpSessionAttributeListener class and implement the attributeRemoved method and log the attribute name using the getName method on the event object.
Create an SessionAttributeListener class and implement the attributeRemoved method and log the attribute name using the getAttributeName method on the event object.
D. Create an SessionAttributeListener class and implement the attributeDeleted method and log the attribute name using the getAttributeName method on the event object.