Flink之Transform操作

时间:2020-01-09
本文章向大家介绍Flink之Transform操作,主要包括Flink之Transform操作使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。
import org.apache.flink.api.common.functions.FilterFunction
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment

object TransformTest {
def main(args: Array[String]): Unit = {
val env = StreamExecutionEnvironment.getExecutionEnvironment
env.setParallelism(1) //设置全局并行度为1

import org.apache.flink.api.scala._
val streamFromFile = env.readTextFile("sensor1.txt")

//1.基本转换算子和简单聚合算子
val dataStream = streamFromFile.map(data => {
val dataArray = data.split(",")
SensorReading(dataArray(0).trim, dataArray(1).trim.toLong, dataArray(2).trim.toDouble)
}
)
//注意观察结果,flink是来一条数据处理一条,所以不会只看到最终求和后的结果
dataStream.keyBy(0).sum(2).print()
dataStream.keyBy("id").sum("temperature").print() //方式二
//例子:输出当前传感器最新的温度加10,而时间戳是上一次数据的时间戳加1
dataStream.keyBy(0).reduce((x, y) => SensorReading(x.id, x.timestamp + 1, y.temperature + 10)).print() //x和y分别代表当前值和新来的值

//2.多流转换算子
//split分流
val splitStream = dataStream.split(sensorData => {
if (sensorData.temperature > 30)
Seq("high")
else
Seq("low")
})
val high = splitStream.select("high")
val low = splitStream.select("low")
val all = splitStream.select("high", "low")
high.print("high temperature")
low.print("low temperature")
all.print("all")

//合并: connect和union
/*
* 1.union之前两个流的类型必须是一样, connect可以不一样, 在之后的coMap中再去调整成为一样的
* 2. connect只能操作两个流, union可以操作多个
*/
val warning = high.map(x => (x.id, x.temperature))
val connectedStream = warning.connect(low)
val coMap = connectedStream.map(
warningData => (warningData._1, warningData._2, "warning"),
safeData => (safeData.id, "safe")
)
coMap.print()

val unionStream = high.union(low)
unionStream.print()

// streamFromFile.map(data => {
// val len = data.split(",")
// len(0) + " " + len(1)
// }).print()

//自定义函数类
dataStream.filter(new MyFilter).print()

env.execute("transform test")
}
}

class MyFilter() extends FilterFunction[SensorReading] {
override def filter(t: SensorReading): Boolean = {
t.id.startsWith("sensor_1")
}
}

原文地址:https://www.cnblogs.com/wddqy/p/12172284.html