Flink window Function - FoldFunction

package window

import org.apache.flink.api.common.functions.{AggregateFunction, FoldFunction}
import org.apache.flink.api.scala._
import org.apache.flink.streaming.api.functions.source.SourceFunction
import org.apache.flink.streaming.api.scala.{StreamExecutionEnvironment, WindowedStream}
import org.apache.flink.streaming.api.windowing.time.Time
import org.apache.flink.streaming.api.windowing.windows.TimeWindow

/**
 * @author: create by maoxiangyi
 * @version: v1.0
 * @description: window
 * @date:2019 /6/4
 */
object FoldWordCount {
 def main(args: Array[String]): Unit = {
  //設置環境
  val env: StreamExecutionEnvironment = StreamExecutionEnvironment.createLocalEnvironment()
  //設置數據源
  val window: WindowedStream[(String, Int), String, TimeWindow] = env.addSource(new SourceFunction[String] {
   override def run(ctx: SourceFunction.SourceContext[String]): Unit = {
    while (true) {
     ctx.collect("hello hadoop hello storm hello spark")
     Thread.sleep(1000)
    }
   }

   override def cancel(): Unit = {}
  })
   //計算邏輯
   .flatMap(_.split(" "))
   .map((_, 1))
   .keyBy(_._1)
   .timeWindow(Time.seconds(10), Time.seconds(10))

  window.fold(("", 0), new FoldFunction[(String, Int), (String, Int)] {
   override def fold(accumulator: (String, Int), value: (String, Int)): (String, Int) = {
    (value._1, value._2 + accumulator._2)
   }
  }).print()

  env.execute("word count")
 }
}