交友网站建设教程广州百度首页优化

一、创建Spark Streaming 环境

二、读取数据（监听端口）

三、任务处理

四、启动程序

我这里写的是简单的单词数量统计

import org.apache.spark.streaming.dstream.{DStream, ReceiverInputDStream}
import org.apache.spark.{SparkConf, SparkContext}
import org.apache.spark.streaming.{Durations, StreamingContext}object Demo1WordCount {def main(args: Array[String]): Unit = {val conf = new SparkConf()conf.setMaster("local[2]")conf.setAppName("wc")val sc = new SparkContext(conf)//1、创建spark streaming环境//指定处理的间隔时间val ssc = new StreamingContext(sc, Durations.seconds(5))//2、读取数据//nc -lk 8888//yum install ncval linesDS: ReceiverInputDStream[String] = ssc.socketTextStream("master", 8888)//统计单词的数量val countDS: DStream[(String, Int)] = linesDS.flatMap(_.split(",")).map((_, 1)).reduceByKey(_ + _)countDS.print()//启动spark streaming程序ssc.start()ssc.awaitTermination()}
}

UpdateStateByKey（有状态算子）能统计之前的单词数量，可做实时更新 

import org.apache.spark.streaming.dstream.{DStream, ReceiverInputDStream}
import org.apache.spark.streaming.{Durations, StreamingContext}
import org.apache.spark.{SparkConf, SparkContext}object Demo2UpdateStateByKey {def main(args: Array[String]): Unit = {val conf = new SparkConf()conf.setMaster("local[2]")conf.setAppName("wc")val sc = new SparkContext(conf)//1、创建spark streaming环境//指定处理的间隔时间val ssc = new StreamingContext(sc, Durations.seconds(5))//设置checkpoint路径//用于保存状态ssc.checkpoint("data/checkpoint")//2、读取数据//nc -lk 8888//yum install ncval linesDS: ReceiverInputDStream[String] = ssc.socketTextStream("master", 8888)//统计单词的数量val kvDS: DStream[(String, Int)] = linesDS.flatMap(_.split(",")).map((_, 1))//updateStateByKey(有状态算子): 每一次计算更新每一个key的状态（单词的数量）val countDS: DStream[(String, Int)] = kvDS.updateStateByKey {/*** seq： 当前批次一个key所有value* state: 之前的结果（状态：之前的单词的数量）*/case (seq: Seq[Int], state: Option[Int]) =>println(seq)println(state)//计算当前批次单词的数量val sum: Int = seq.sum//获取之前单词的数量val count: Int = state match {case Some(count) => countcase None => 0}//计算新的单词的数量并返回Option(sum + count)}countDS.print()//启动spark streaming程序ssc.start()ssc.awaitTermination()}
}