sparkStreaming消费kafka-0.8方式：direct方式（存储offset到zookeeper）

生产中，为了保证kafka的offset的安全性，并且防止丢失数据现象，会手动维护偏移量（offset）

版本：kafka：0.8

其中需要注意的点：

1：获取zookeeper记录的分区偏移量

2：获取broker中实际的最小和最大偏移量

3：将实际的偏移量和zookeeper记录的偏移量进行对比，如果zookeeper中记录的偏移量在实际的偏移量范围内则使用zookeeper中的偏移量

4：反之，使用实际的broker中的最小偏移量

KafkaHelper：

import kafka.common.TopicAndPartition
import kafka.message.MessageAndMetadata
import kafka.serializer.StringDecoder
import kafka.utils.{ZKGroupTopicDirs, ZkUtils}
import org.I0Itec.zkclient.ZkClient
import org.apache.spark.SparkException
import org.apache.spark.streaming.StreamingContext
import org.apache.spark.streaming.dstream.InputDStream
import org.apache.spark.streaming.kafka.{KafkaCluster, KafkaUtils, OffsetRange}
import org.apache.spark.streaming.kafka.KafkaCluster.Err

/**
  * KafkaHelper类提供两个共有方法，一个用来创建direct方式的DStream，另一个用来更新zookeeper中的消费偏移量
  * @param kafkaPrams kafka配置参数
  * @param zkQuorum zookeeper列表
  * @param group 消费组
  * @param topic 消费主题
  */
class KafkaHelper(kafkaPrams:Map[String,String],zkQuorum:String,group:String,topic:String) extends Serializable{

  private val kc = new KafkaCluster(kafkaPrams)
  private val zkClient = new ZkClient(zkQuorum)
  private val topics = Set(topic)

  /**
    * 获取消费组group下的主题topic在zookeeper中的保存路径
    * @return
    */
  private def getZkPath():String={
    val topicDirs = new ZKGroupTopicDirs(group,topic)
    val zkPath = topicDirs.consumerOffsetDir
    zkPath
  }

  /**
    * 获取偏移量信息
    * @param children 分区数
    * @param zkPath zookeeper中的topic信息的路径
    * @param earlistLeaderOffsets broker中的实际最小偏移量
    * @param latestLeaderOffsets broker中的实际最大偏移量
    * @return
    */
  private def getOffsets(children:Int,zkPath:String,earlistLeaderOffsets:Map[TopicAndPartition, KafkaCluster.LeaderOffset],latestLeaderOffsets: Map[TopicAndPartition, KafkaCluster.LeaderOffset]): Map[TopicAndPartition, Long] = {
    var fromOffsets: Map[TopicAndPartition, Long] = Map()
    for(i <- 0 until children){
      //获取zookeeper记录的分区偏移量
      val zkOffset = zkClient.readData[String](s"${zkPath}/${i}").toLong
      val tp = TopicAndPartition(topic,i)
      //获取broker中实际的最小和最大偏移量
      val earlistOffset: Long = earlistLeaderOffsets(tp).offset
      val latestOffset: Long = latestLeaderOffsets(tp).offset
      //将实际的偏移量和zookeeper记录的偏移量进行对比，如果zookeeper中记录的偏移量在实际的偏移量范围内则使用zookeeper中的偏移量，
      //反之，使用实际的broker中的最小偏移量
      if(zkOffset>=earlistOffset && zkOffset<=latestOffset) {
        fromOffsets += (tp -> zkOffset)
      }else{
        fromOffsets += (tp -> earlistOffset)
      }
    }
    fromOffsets
  }

  /**
    * 创建DStream
    * @param ssc
    * @return
    */
  def createDirectStream(ssc:StreamingContext):InputDStream[(String, String)]={
    //----------------------获取broker中实际偏移量---------------------------------------------
    val partitionsE: Either[Err, Set[TopicAndPartition]] = kc.getPartitions(topics)
    if(partitionsE.isLeft)
      throw new SparkException("get kafka partitions failed:")
    val partitions = partitionsE.right.get
    val earlistLeaderOffsetsE: Either[Err, Map[TopicAndPartition, KafkaCluster.LeaderOffset]] = kc.getEarliestLeaderOffsets(partitions)
    if(earlistLeaderOffsetsE.isLeft)
      throw new SparkException("get kafka earlistLeaderOffsets failed:")
    val earlistLeaderOffsets: Map[TopicAndPartition, KafkaCluster.LeaderOffset] = earlistLeaderOffsetsE.right.get
    val latestLeaderOffsetsE: Either[Err, Map[TopicAndPartition, KafkaCluster.LeaderOffset]] = kc.getLatestLeaderOffsets(partitions)
    if(latestLeaderOffsetsE.isLeft)
      throw new SparkException("get kafka latestLeaderOffsets failed:")
    val latestLeaderOffsets: Map[TopicAndPartition, KafkaCluster.LeaderOffset] = latestLeaderOffsetsE.right.get
    //----------------------创建kafkaStream----------------------------------------------------
    var kafkaStream:InputDStream[(String, String)]=null
    val zkPath: String = getZkPath()
    val children = zkClient.countChildren(zkPath)
    //根据zookeeper中是否有偏移量数据判断有没有消费过kafka中的数据
    if(children > 0){
      val fromOffsets:Map[TopicAndPartition, Long] = getOffsets(children,zkPath,earlistLeaderOffsets,latestLeaderOffsets)
      val messageHandler = (mmd: MessageAndMetadata[String, String]) => (mmd.topic, mmd.message())
      //如果消费过，根据偏移量创建Stream
      kafkaStream = KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder, (String, String)](
        ssc, kafkaPrams, fromOffsets, messageHandler)
    }else{
      //如果没有消费过，根据kafkaPrams配置信息从最早的数据开始创建Stream
      kafkaStream = KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder](ssc, kafkaPrams, topics)
    }
    kafkaStream
  }

  /**
    * 更新zookeeper中的偏移量
    * @param offsetRanges
    */
  def updateZkOffsets(offsetRanges:Array[OffsetRange])={
    val zkPath: String = getZkPath()
    for( o <- offsetRanges){
      val newZkPath = s"${zkPath}/${o.partition}"
      //将该 partition 的 offset 保存到 zookeeper
      ZkUtils.updatePersistentPath(zkClient, newZkPath, o.fromOffset.toString)
    }
  }
}

　　

驱动类：

package CC

import org.apache.spark.SparkConf
import org.apache.spark.sparkStreaming.kafka.KafkaHelper
import org.apache.spark.streaming.dstream.InputDStream
import org.apache.spark.streaming.kafka.{HasOffsetRanges, OffsetRange}
import org.apache.spark.streaming.{Seconds, StreamingContext}

/**
  * Created by angel；
  */
object TestKafkaHelper {
  def main(args: Array[String]): Unit = {

    val Array(timeInterval,brokerList,zkQuorum,topic,group) = Array(
      "2"
      , "hadoop01:9092,hadoop02:9092,hadoop03:9092"
      , "hadoop01:2181,hadoop02:2181,hadoop03:2181"
      , "CustomerContacts"
      , "CustomerContacts"
    )

    val conf = new SparkConf().setAppName("KafkaDirectStream").setMaster("local[2]")
    val ssc = new StreamingContext(conf,Seconds(timeInterval.toInt))

    //kafka配置参数
    val kafkaParams = Map(
      "metadata.broker.list" -> brokerList,
      "group.id" -> group,
      "auto.offset.reset" -> kafka.api.OffsetRequest.SmallestTimeString
    )

    val kafkaHelper = new KafkaHelper(kafkaParams,zkQuorum,topic,group)

    val kafkaStream: InputDStream[(String, String)] = kafkaHelper.createDirectStream(ssc)

    var offsetRanges = Array[OffsetRange]()

    kafkaStream.transform( rdd =>{
      offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
      rdd
    }).map( msg => msg._2)
      .foreachRDD( rdd => {
        rdd.foreachPartition( partition =>{
          partition.foreach( record =>{
            //处理数据的方法
            println(record)
          })
        })
        kafkaHelper.updateZkOffsets(offsetRanges)
      })

    ssc.start()
    ssc.awaitTermination()
    ssc.stop()
  }

}