Flink 基本算子map、keyBy、sum、reduce

核心代码：

object TransformTest {

  def main(args: Array[String]): Unit = {
    val env = StreamExecutionEnvironment.getExecutionEnvironment
    env.setParallelism(1)

    val streamFromFile = env.readTextFile("C:\Users\Mi\Documents\project\idea\FlinkTitorial\src\main\resources\sensor.txt")

    //------------map--------------
    val dataStream1: DataStream[SensorReading] = streamFromFile.map(d => {
      val arr = d.split(",")
      SensorReading(arr(0).trim, arr(1).trim.toLong, arr(2).toDouble)
    })

    //------------keyBY--------------
    //此时key是一个元组
    val dataStream2: KeyedStream[SensorReading, Tuple] = dataStream1.keyBy(0)
    val dataStream3: KeyedStream[SensorReading, Tuple] = dataStream1.keyBy("id")
    //此时key是字段的类型
    val dataStream4: KeyedStream[SensorReading, String] = dataStream1.keyBy(_.id)

    //------------sum--------------
    val dataStream5 = dataStream4.sum(2)
    val dataStream6 = dataStream4.sum("temperature")

    //------------reduce-----------
    //温度求和。sr1是上一次的结果，sr2是遍历到的当前的SensorReading对象
    val dataStream7 = dataStream4.reduce((sr1, sr2) => SensorReading(sr2.id, sr2.timestamp, sr1.temperature + sr2.temperature))

    dataStream7.print

    env.execute("transform test")
  }

}

case class SensorReading(id: String, timestamp: Long, temperature: Double)

sensor.txt文件内容：

sensor_1, 1547718199, 35.80018327300259
sensor_6, 1547718201, 15.402984393403084
sensor_7, 1547718202, 6.720945201171228
sensor_10, 1547718205, 38.101067604893444
sensor_1, 1547718200, 30.8
sensor_1, 1547718201, 40.8

输出结果：

SensorReading(sensor_1,1547718199,35.80018327300259)
SensorReading(sensor_6,1547718201,15.402984393403084)
SensorReading(sensor_7,1547718202,6.720945201171228)
SensorReading(sensor_10,1547718205,38.101067604893444)
SensorReading(sensor_1,1547718200,66.60018327300259)
SensorReading(sensor_1,1547718201,107.40018327300258)