Spark自定义维护kafka的offset到zk

import kafka.common.TopicAndPartition
import kafka.message.MessageAndMetadata
import kafka.serializer.StringDecoder
import kafka.utils.ZkUtils
import org.I0Itec.zkclient.ZkClient
import org.apache.spark.SparkConf
import org.apache.spark.rdd.RDD
import org.apache.spark.streaming.dstream.InputDStream
import org.apache.spark.streaming.kafka.{HasOffsetRanges, KafkaUtils}
import org.apache.spark.streaming.{Seconds, StreamingContext}

object DirectKafkaExample {

def main(args: Array[String]) {

val ssc =  setupSsc
ssc.start()
ssc.awaitTermination()

}

def setupSsc(): StreamingContext ={

val conf = new SparkConf().setAppName("CustomDirectKafkaExample").setMaster("local")
val kafkaParams:Map[String,String] = Map("metadata.broker.list" -> "slave1:9092,slave2:9092,slave3:9092")
val topicsSet = Set("testha")
val ssc = new StreamingContext(conf, Seconds(5))

val messages = createCustomDirectKafkaStream(ssc,kafkaParams,"master0:2181,slave1:2181,slave3:2181","/mysefloffset", topicsSet).map(_._2)

messages.foreachRDD{rdd => {
rdd.foreachPartition { partitionOfRecords =>
if(partitionOfRecords.isEmpty)
{
println("此分区数据为空.")
}
else
{
partitionOfRecords.foreach(println(_))
}
}

}
}
ssc
}

def createCustomDirectKafkaStream(ssc: StreamingContext, kafkaParams: Map[String, String], zkHosts: String
, zkPath: String, topics: Set[String]): InputDStream[(String, String)] = {
val topic = topics.last
val zkClient = new ZkClient(zkHosts, 30000, 30000)
val storedOffsets = readOffsets(zkClient,zkHosts, zkPath, topic)

val kafkaStream = storedOffsets match {
case None => //最新的offset
KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder](ssc, kafkaParams, topics)

case Some(fromOffsets) => // offset从上次继续开始
val messageHandler = (mmd: MessageAndMetadata[String, String]) => (mmd.key, mmd.message)
KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder,(String, String)](ssc, kafkaParams, fromOffsets, messageHandler)
}

// save the offsets
kafkaStream.foreachRDD(rdd => saveOffsets(zkClient,zkHosts, zkPath, rdd))
kafkaStream

}

private def readOffsets(zkClient: ZkClient,zkHosts:String, zkPath: String, topic: String):Option[Map[TopicAndPartition, Long]] = {

println("开始读取从zk中读取offset")

val stopwatch = new Stopwatch()

val (offsetsRangesStrOpt, _) = ZkUtils.readDataMaybeNull(zkClient, zkPath)
offsetsRangesStrOpt match {
case Some(offsetsRangesStr) =>
println(s"读取到的offset范围: ${offsetsRangesStr}")
val offsets = offsetsRangesStr.split(",")
.map(s => s.split(":"))
.map { case Array(partitionStr, offsetStr) => (TopicAndPartition(topic, partitionStr.toInt) -> offsetStr.toLong) }
.toMap
println("读取offset结束: " + stopwatch)
Some(offsets)
case None =>
println("读取offset结束: " + stopwatch)
None
}
}

private def saveOffsets(zkClient: ZkClient,zkHosts:String, zkPath: String, rdd: RDD[_]): Unit = {
println("开始保存offset到zk中去")

val stopwatch = new Stopwatch()
val offsetsRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges

//分区,offset
offsetsRanges.foreach(offsetRange => println(s"Using ${offsetRange}"))

val offsetsRangesStr = offsetsRanges.map(offsetRange => s"${offsetRange.partition}:${offsetRange.fromOffset}").mkString(",")
println("保存的偏移量范围:"+ offsetsRangesStr)
ZkUtils.updatePersistentPath(zkClient, zkPath, offsetsRangesStr)
println("保存结束,耗时 ：" + stopwatch)
}

class Stopwatch {
private val start = System.currentTimeMillis()
override def toString() = (System.currentTimeMillis() - start) + " ms"
}

}