使用Flink怎么实时计算网站Pv和Uv，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
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Flink数据流上的类型和操作
DataStream是flink流处理最核心的数据结构，其它的各种流都可以直接或者间接通过DataStream来完成相互转换，一些常用的流直接的转换关系如图：
可以看出，DataStream可以与KeyedStream相互转换，KeyedStream可以转换为WindowedStream，DataStream不能直接转换为WindowedStream，WindowedStream可以直接转换为DataStream。各种流之间虽然不能相互直接转换，但是都可以通过先转换为DataStream，再转换为其它流的方法来实现。
在这个计算pv,uv的需求中就主要用到DataStream、KeyedStream以及WindowedStream这些数据结构。
这里需要用到window和watermark，使用窗口把数据按天分割，使用watermark可以通过“水位”来定期清理窗口外的迟到数据，起到清理内存的作用。
业务代码
我们的数据是json类型的，含有date,version,guid这3个字段，在实时统计pv,uv这个功能中，其它字段可以直接丢掉，当然了在离线数据仓库中，所有有含义的业务字段都是要保留到hive当中的。其它相关概念就不说了，会专门介绍，这里直接上代码吧。
4.0.0 com.ddxygq bigdata 1.0-SNAPSHOT 2.11.8 1.7.0 bigdata org.apache.flink flink-scala_2.11 {flink.version} org.apache.flink flink-streaming-scala_2.11 flink.version org.apache.flink flink-streaming-java_2.11 {flink.version} org.apache.flink flink-connector-kafka-0.10_2.11 flink.version basedir/src/test−−>{pkg.name} src/main/java src/main/resources *.properties *.xml false org.apache.maven.plugins maven-surefire-plugin true org.scala-tools maven-scala-plugin 2.15.2 compile testCompile
主要代码，主要使用scala开发：
package com.ddxygq.bigdata.flink.streaming.pvuv import java.util.Properties import com.alibaba.fastjson.JSON import org.apache.flink.runtime.state.filesystem.FsStateBackend import org.apache.flink.streaming.api.CheckpointingMode import org.apache.flink.streaming.api.functions.timestamps.BoundedOutOfOrdernessTimestampExtractor import org.apache.flink.streaming.api.scala.{DataStream, StreamExecutionEnvironment} import org.apache.flink.streaming.api.windowing.time.Time import org.apache.flink.streaming.api.windowing.triggers.ContinuousProcessingTimeTrigger import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer010 import org.apache.flink.streaming.util.serialization.SimpleStringSchema import org.apache.flink.streaming.api.scala.extensions._ import org.apache.flink.api.scala._ /** * @ Author: keguang * @ Date: 2019/3/18 17:34 * @ version: v1.0.0 * @ description: */ object PvUvCount { def main(args: Array[String]): Unit = { val env = StreamExecutionEnvironment.getExecutionEnvironment // 容错 env.enableCheckpointing(5000) env.getCheckpointConfig.setCheckpointingMode(CheckpointingMode.EXACTLY_ONCE) env.setStateBackend(new FsStateBackend("file:///D:/space/IJ/bigdata/src/main/scala/com/ddxygq/bigdata/flink/checkpoint/flink/tagApp")) // kafka 配置 val ZOOKEEPER_HOST = "hadoop01:2181,hadoop02:2181,hadoop03:2181" val KAFKA_BROKERS = "hadoop01:9092,hadoop02:9092,hadoop03:9092" val TRANSACTION_GROUP = "flink-count" val TOPIC_NAME = "flink" val kafkaProps = new Properties() kafkaProps.setProperty("zookeeper.connect", ZOOKEEPER_HOST) kafkaProps.setProperty("bootstrap.servers", KAFKA_BROKERS) kafkaProps.setProperty("group.id", TRANSACTION_GROUP) // watrmark 允许数据延迟时间 val MaxOutOfOrderness = 86400 * 1000L // 消费kafka数据 val streamData: DataStream[(String, String, String)] = env.addSource( new FlinkKafkaConsumer010[String](TOPIC_NAME, new SimpleStringSchema(), kafkaProps) ).assignTimestampsAndWatermarks(new BoundedOutOfOrdernessTimestampExtractor[String](Time.milliseconds(MaxOutOfOrderness)) { override def extractTimestamp(element: String): Long = { val t = JSON.parseObject(element) val time = JSON.parseObject(JSON.parseObject(t.getString("message")).getString("decrypted_data")).getString("time") time.toLong } }).map(x => { var date = "error" var guid = "error" var helperversion = "error" try { val messageJsonObject = JSON.parseObject(JSON.parseObject(x).getString("message")) val datetime = messageJsonObject.getString("time") date = datetime.split(" ")(0) // hour = datetime.split(" ")(1).substring(0, 2) val decrypted_data_string = messageJsonObject.getString("decrypted_data") if (!"".equals(decrypted_data_string)) { val decrypted_data = JSON.parseObject(decrypted_data_string) guid = decrypted_data.getString("guid").trim helperversion = decrypted_data.getString("helperversion") } } catch { case e: Exception => { println(e) } } (date, helperversion, guid) }) // 这上面是设置watermark并解析json部分 // 聚合窗口中的数据，可以研究下applyWith这个方法和OnWindowedStream这个类 val resultStream = streamData.keyBy(x => { x._1 + x._2 }).timeWindow(Time.days(1)) .trigger(ContinuousProcessingTimeTrigger.of(Time.seconds(1))) .applyWith(("", List.empty[Int], Set.empty[Int], 0L, 0L))( foldFunction = { case ((_, list, set, _, 0), item) => { val date = item._1 val helperversion = item._2 val guid = item._3 (date + "_" + helperversion, guid.hashCode +: list, set + guid.hashCode, 0L, 0L) } } , windowFunction = { case (key, window, result) => { result.map { case (leixing, list, set, _, _) => { (leixing, list.size, set.size, window.getStart, window.getEnd) } } } } ).keyBy(0) .flatMapWithState[(String, Int, Int, Long, Long),(Int, Int)]{ case ((key, numpv, numuv, begin, end), curr) => curr match { case Some(numCurr) if numCurr == (numuv, numpv) => (Seq.empty, Some((numuv, numpv))) //如果之前已经有相同的数据,则返回空结果 case _ => (Seq((key, numpv, numuv, begin, end)), Some((numuv, numpv))) } } // 最终结果 val resultedStream = resultStream.map(x => { val keys = x._1.split("_") val date = keys(0) val helperversion = keys(1) (date, helperversion, x._2, x._3) }) resultedStream.print() env.execute("PvUvCount") } }使用List集合的size保存pv,使用Set集合的size保存uv，从而达到实时统计pv,uv的目的。
这里用了几个关键的函数：
applyWith：里面需要的参数，初始状态变量，和foldFunction ，windowFunction ;
存在的问题
显然，当数据量很大的时候，这个List集合和Set集合会很大，并且这里的pv是否可以不用List来存储，而是通过一个状态变量，不断做累加，对应操作就是更新状态来完成。
改进版
使用了一个计数器来存储pv的值。
packagecom.ddxygq.bigdata.flink.streaming.pvuv import java.util.Properties import com.alibaba.fastjson.JSON import org.apache.flink.api.common.accumulators.IntCounter import org.apache.flink.runtime.state.filesystem.FsStateBackend import org.apache.flink.streaming.api.CheckpointingMode import org.apache.flink.streaming.api.functions.timestamps.BoundedOutOfOrdernessTimestampExtractor import org.apache.flink.streaming.api.scala.{DataStream, StreamExecutionEnvironment} import org.apache.flink.streaming.api.windowing.time.Time import org.apache.flink.streaming.api.windowing.triggers.ContinuousProcessingTimeTrigger import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer010 import org.apache.flink.streaming.util.serialization.SimpleStringSchema import org.apache.flink.streaming.api.scala.extensions._ import org.apache.flink.api.scala._ import org.apache.flink.core.fs.FileSystem object PvUv2 { def main(args: Array[String]): Unit = { val env = StreamExecutionEnvironment.getExecutionEnvironment // 容错 env.enableCheckpointing(5000) env.getCheckpointConfig.setCheckpointingMode(CheckpointingMode.EXACTLY_ONCE) env.setStateBackend(new FsStateBackend("file:///D:/space/IJ/bigdata/src/main/scala/com/ddxygq/bigdata/flink/checkpoint/streaming/counter")) // kafka 配置 val ZOOKEEPER_HOST = "hadoop01:2181,hadoop02:2181,hadoop03:2181" val KAFKA_BROKERS = "hadoop01:9092,hadoop02:9092,hadoop03:9092" val TRANSACTION_GROUP = "flink-count" val TOPIC_NAME = "flink" val kafkaProps = new Properties() kafkaProps.setProperty("zookeeper.connect", ZOOKEEPER_HOST) kafkaProps.setProperty("bootstrap.servers", KAFKA_BROKERS) kafkaProps.setProperty("group.id", TRANSACTION_GROUP) // watrmark 允许数据延迟时间 val MaxOutOfOrderness = 86400 * 1000L val streamData: DataStream[(String, String, String)] = env.addSource( new FlinkKafkaConsumer010[String](TOPIC_NAME, new SimpleStringSchema(), kafkaProps) ).assignTimestampsAndWatermarks(new BoundedOutOfOrdernessTimestampExtractor[String](Time.milliseconds(MaxOutOfOrderness)) { override def extractTimestamp(element: String): Long = { val t = JSON.parseObject(element) val time = JSON.parseObject(JSON.parseObject(t.getString("message")).getString("decrypted_data")).getString("time") time.toLong } }).map(x => { var date = "error" var guid = "error" var helperversion = "error" try { val messageJsonObject = JSON.parseObject(JSON.parseObject(x).getString("message")) val datetime = messageJsonObject.getString("time") date = datetime.split(" ")(0) // hour = datetime.split(" ")(1).substring(0, 2) val decrypted_data_string = messageJsonObject.getString("decrypted_data") if (!"".equals(decrypted_data_string)) { val decrypted_data = JSON.parseObject(decrypted_data_string) guid = decrypted_data.getString("guid").trim helperversion = decrypted_data.getString("helperversion") } } catch { case e: Exception => { println(e) } } (date, helperversion, guid) }) val resultStream = streamData.keyBy(x => { x._1 + x._2 }).timeWindow(Time.days(1)) .trigger(ContinuousProcessingTimeTrigger.of(Time.seconds(1))) .applyWith(("", new IntCounter(), Set.empty[Int], 0L, 0L))( foldFunction = { case ((_, cou, set, _, 0), item) => { val date = item._1 val helperversion = item._2 val guid = item._3 cou.add(1) (date + "_" + helperversion, cou, set + guid.hashCode, 0L, 0L) } } , windowFunction = { case (key, window, result) => { result.map { case (leixing, cou, set, _, _) => { (leixing, cou.getLocalValue, set.size, window.getStart, window.getEnd) } } } } ).keyBy(0) .flatMapWithState[(String, Int, Int, Long, Long),(Int, Int)]{ case ((key, numpv, numuv, begin, end), curr) => curr match { case Some(numCurr) if numCurr == (numuv, numpv) => (Seq.empty, Some((numuv, numpv))) //如果之前已经有相同的数据,则返回空结果 case _ => (Seq((key, numpv, numuv, begin, end)), Some((numuv, numpv))) } } // 最终结果 val resultedStream = resultStream.map(x => { val keys = x._1.split("_") val date = keys(0) val helperversion = keys(1) (date, helperversion, x._2, x._3) }) val resultPath = "D:\\space\\IJ\\bigdata\\src\\main\\scala\\com\\ddxygq\\bigdata\\flink\\streaming\\pvuv\\result" resultedStream.writeAsText(resultPath, FileSystem.WriteMode.OVERWRITE) env.execute("PvUvCount") } }看完上述内容，你们掌握使用Flink怎么实时计算网站Pv和Uv的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注创新互联行业资讯频道，感谢各位的阅读！
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