Flink之API的使用（2）：Transform算子的使用

相关文章链接

Flink之API的使用（1）：Sink的使用

Flink之API的使用（2）：Transform算子的使用

Flink之API的使用（3）：Source的使用

具体代码实现如下所示：

// 执行环境
val env: StreamExecutionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment
env.setParallelism(2)

// 获取数据，并转换成流
val fileStream: DataStream[String] = env.readTextFile("D:\\Project\\IDEA\\bigdata-study\\flink-demo\\src\\main\\resources\\source.txt")

// 1、map
val mapStream: DataStream[SensorReading] = fileStream.map(data => {
    val fields: Array[String] = data.split(",")
    SensorReading(fields(0).trim, fields(1).trim.toLong, fields(2).trim.toDouble)
})

// 2、filter
val filterStream: DataStream[SensorReading] = mapStream.filter(_.id == "sensor_1")

// 3、flatMap
val flatMapStream: DataStream[String] = fileStream.flatMap(_.split(","))

// 4、keyBy
val keyByStream: KeyedStream[SensorReading, String] = mapStream.keyBy(_.id)

// 5、Rolling Aggregation（滚动聚合算子，需要先进行keyBy，才进行聚合，包括sum,min,max,minBy,maxBy）
val sumStream: DataStream[SensorReading] = keyByStream.sum("temperature")
val maxStream: DataStream[SensorReading] = keyByStream.max(2)

// 6、reduce
val reduceStream: DataStream[SensorReading] = keyByStream.reduce((x, y) => SensorReading(x.id, y.timestamp, x.temperature + y.temperature))

// 7、Split 和 Select
val splitStream: SplitStream[SensorReading] = mapStream.split(sensorReading => {
    if (sensorReading.temperature < 30) Seq("low") else Seq("high")
})
val lowStream: DataStream[SensorReading] = splitStream.select("low")
val highStream: DataStream[SensorReading] = splitStream.select("high")
val allStream: DataStream[SensorReading] = splitStream.select("low", "high")

// 8、Connect和 CoMap
val warning: DataStream[(String, Double)] = highStream.map(sonsorData => (sonsorData.id, sonsorData.temperature))
val connected: ConnectedStreams[(String, Double), SensorReading] = warning.connect(lowStream)
val connectedResult: DataStream[Product] = connected.map(
    warningData => (warningData._1, warningData._2, "warning"),
    lowData => (lowData.id, "healthy")
)

// 9、Union
val unionStream: DataStream[SensorReading] = lowStream.union(highStream)

// 打印数据
unionStream.print()

// 启动执行环境，开始任务
env.execute("TransformDemo")