class MyRichMapper extends RichMapFunction[SensorReding,String]{ override def open(parameters: Configuration): Unit = { //做一些初始化操作,比如数据库的连接 // getRuntimeContext } override def map(in: SensorReding): String = in.id+"temperature" override def close(): Unit = { //一般做收尾工作,比如关闭连接,或者清空状态 } } }