Spark系列--Spark Streaming(四)DStreams输入--高级数据源之Kafka

我会带着你远行 2022-05-18 07:08 177阅读 0赞

## 前言 ##

本篇主要介绍Spark Streaming如何集成Kafka，演示SparkStreaming如何从Kafka读取消息，如果通过连接池方法把消息处理完成后再写会Kafka。

![这里写图片描述][70]

在工程中需要引入Maven工件来使用它。包内提供的 KafkaUtils 对象可以在 StreamingContext 和JavaStreamingContext 中以你的 Kafka 消息创建出 DStream。由于 KafkaUtils 可以订阅多个主题，因此它创建出的 DStream 由成对的主题和消息组成。要创建出一个流数据，需 要使用 StreamingContext 实例、一个由逗号隔开的 ZooKeeper 主机列表字符串、消费者组的名字(唯一名字)，以及一个从主题到针对这个主题的接收器线程数的映射表来调用 createStream() 方法。

import org.apache.spark.streaming.kafka._
     ...
      // 创建一个从主题到接收器线程数的映射表 
        val topics = List(("pandas", 1), ("logs", 1)).toMap 
        
          val topicLines = KafkaUtils.createStream(ssc, zkQuorum, group, topics) 
          
    topicLines.map(_._2)

--------------------

## 一、IDEA编写代码 ##

**1、在原Spark Streaming项目基础上创建集成Kafka子项目并添加如下Maven依赖**

<dependency>
                <groupId>org.apache.commons</groupId>
                <artifactId>commons-pool2</artifactId>
                <version>2.4.2</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.apache.kafka</groupId>
                <artifactId>kafka-clients</artifactId>
                <version>0.10.2.1</version>
            </dependency>
    
            <dependency>
                <groupId>org.apache.spark</groupId>
                <artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
                <version>${spark.version}</version>
            </dependency>

**2、完整代码如下：**

**构建Kafka生产者连接池类**

package com.m.jd.streaming
    
    import org.apache.commons.pool2.impl.{GenericObjectPool, GenericObjectPoolConfig}
    
    //单例对象
    object createKafkaProducerPool{ 
    
      //用于返回真正的对象池GenericObjectPool
      def apply(brokerList: String, topic: String):  GenericObjectPool[KafkaProducerProxy] = {
        val producerFactory = new BaseKafkaProducerFactory(brokerList, defaultTopic = Option(topic))
        val pooledProducerFactory = new PooledKafkaProducerAppFactory(producerFactory)
        //指定了你的kafka对象池的大小
        val poolConfig = {
          val c = new GenericObjectPoolConfig
          val maxNumProducers = 10
          c.setMaxTotal(maxNumProducers)
          c.setMaxIdle(maxNumProducers)
          c
        }
        //返回一个对象池
        new GenericObjectPool[KafkaProducerProxy](pooledProducerFactory, poolConfig)
      }
    }

**Kafka生产者代理对象：**

package com.m.jd.streaming
    import java.util.Properties
    import org.apache.commons.pool2.impl.DefaultPooledObject
    import org.apache.commons.pool2.{BasePooledObjectFactory, PooledObject}
    import org.apache.kafka.clients.producer.{KafkaProducer, ProducerRecord}
    
    
    case class KafkaProducerProxy(brokerList: String, producerConfig: Properties = new Properties, defaultTopic: Option[String] = None, producer: Option[KafkaProducer[String, String]] = None) { 
    
      type Key = String
      type Val = String
    
      require(brokerList == null || !brokerList.isEmpty, "Must set broker list")
    
      private val p = producer getOrElse {
    
        var props:Properties= new Properties();
        props.put("bootstrap.servers", brokerList);
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
    
        new KafkaProducer[String,String](props)
      }
    
    
      //把我的消息包装成了ProducerRecord
      private def toMessage(value: Val, key: Option[Key] = None, topic: Option[String] = None): ProducerRecord[Key, Val] = {
        val t = topic.getOrElse(defaultTopic.getOrElse(throw new IllegalArgumentException("Must provide topic or default topic")))
        require(!t.isEmpty, "Topic must not be empty")
        key match {
          case Some(k) => new ProducerRecord(t, k, value)
          case _ => new ProducerRecord(t, value)
        }
      }
    
      def send(key: Key, value: Val, topic: Option[String] = None) {
        //调用KafkaProducer他的send方法发送消息
        p.send(toMessage(value, Option(key), topic))
      }
    
      def send(value: Val, topic: Option[String]) {
        send(null, value, topic)
      }
    
      def send(value: Val, topic: String) {
        send(null, value, Option(topic))
      }
    
      def send(value: Val) {
        send(null, value, None)
      }
    
      def shutdown(): Unit = p.close()
    
    }
    
    
    abstract class KafkaProducerFactory(brokerList: String, config: Properties, topic: Option[String] = None) extends Serializable { 
    
      def newInstance(): KafkaProducerProxy
    }
    
    class BaseKafkaProducerFactory(brokerList: String, config: Properties = new Properties, defaultTopic: Option[String] = None)
      extends KafkaProducerFactory(brokerList, config, defaultTopic) {
    
      override def newInstance() = new KafkaProducerProxy(brokerList, config, defaultTopic)
    
    }
    
    // 继承一个基础的连接池，需要提供池化的对象类型
    class PooledKafkaProducerAppFactory(val factory: KafkaProducerFactory)
      extends BasePooledObjectFactory[KafkaProducerProxy] with Serializable {
    
      // 用于池来创建对象
      override def create(): KafkaProducerProxy = factory.newInstance()
    
      // 用于池来包装对象
      override def wrap(obj: KafkaProducerProxy): PooledObject[KafkaProducerProxy] = new DefaultPooledObject(obj)
    
      // 用于池来销毁对象
      override def destroyObject(p: PooledObject[KafkaProducerProxy]): Unit = {
        p.getObject.shutdown()
        super.destroyObject(p)
      }
    
    }

**Spark Streaming集成Kafka类：**

package com.m.jd.streaming
    
    import org.apache.kafka.common.serialization.StringDeserializer
    import org.apache.spark.SparkConf
    import org.apache.spark.streaming.kafka010._
    import org.apache.spark.streaming.{Seconds, StreamingContext}
    
    object KafkaStreaming { 
    
      def main(args: Array[String]) {
    
        //设置sparkconf
        val conf = new SparkConf().setMaster("local[4]").setAppName("Spark Streaming Kafka")
        //新建了streamingContext
        val ssc = new StreamingContext(conf, Seconds(1))
    
        //kafka的地址
        val brobrokers = "192.168.10.30:9092,192.168.10.31:9092,192.168.10.32:9092"
        //kafka的队列名称
        val sourcetopic="source";
        //kafka的队列名称
        val targettopic="target";
    
        //创建消费者组名
        var group="con-consumer-group"
    
        //kafka消费者配置
        val kafkaParam = Map(
          "bootstrap.servers" -> brobrokers,//用于初始化链接到集群的地址
          "key.deserializer" -> classOf[StringDeserializer],
          "value.deserializer" -> classOf[StringDeserializer],
          //用于标识这个消费者属于哪个消费团体
          "group.id" -> group,
          //如果没有初始化偏移量或者当前的偏移量不存在任何服务器上，可以使用这个配置属性
          //可以使用这个配置，latest自动重置偏移量为最新的偏移量
          "auto.offset.reset" -> "latest",
          //如果是true，则这个消费者的偏移量会在后台自动提交
          "enable.auto.commit" -> (false: java.lang.Boolean)
          //ConsumerConfig.GROUP_ID_CONFIG
        );
    
        //创建DStream，返回接收到的输入数据
        val stream = KafkaUtils.createDirectStream[String,String](ssc, LocationStrategies.PreferConsistent,ConsumerStrategies.Subscribe[String,String](Array(sourcetopic),kafkaParam))
    
        //定义偏移量数组
        var offsetRanges = Array[OffsetRange]()
    
        stream.transform { rdd =>
          //获取offset信息
          offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
          rdd
        }.map(
          //每一个stream都是一个ConsumerRecord
          s =>("id:" + s.key(),">>>>:"+s.value())
        ).foreachRDD(
          rdd => {
            //对于RDD的每一个分区执行一个操作
            rdd.foreachPartition(partitionOfRecords => {
              // kafka连接池。
              val pool = createKafkaProducerPool(brobrokers, targettopic)
              //从连接池里面取出了一个Kafka的连接
              val p = pool.borrowObject()
    
              //发送当前分区里面每一个数据
              partitionOfRecords.foreach {
                  message => System.out.println(message._2)
                  p.send(message._2,Option(targettopic))
              }
    
              // 使用完了需要将kafka还回去
              pool.returnObject(p)
    
              for( o <- offsetRanges ){
                //打印offset信息..
                println(s"${o.topic} ${o.partition} ${o.fromOffset} ${o.untilOffset}")
              }
    
            })
    
        })
    
        ssc.start()
        ssc.awaitTermination()
    
      }
    
    }

## 二、部署及测试 ##

**1、启动zookeeper和kafka**

参考[Kafka集群搭建][Kafka]

**2、创建两个topic，一个为source，一个为target**

bin/kafka-topics.sh --create --zookeeper 192.168.10.30:2181,192.168.10.31:2181,192.168.10.32:2181 --replication-factor 2 --partitions 2 --topic source

bin/kafka-topics.sh --create --zookeeper 192.168.10.30:2181,192.168.10.31:2181,192.168.10.32:2181 --replication-factor 2 --partitions 2 --topic target

**3、启动kafka console producer 写入source topic**

bin/kafka-console-producer.sh --broker-list 192.168.10.30:9092,192.168.10.31:9092,192.168.10.32:9092 --topic source

**4、启动kafka console consumer 监听target topic**

bin/kafka-console-consumer.sh --bootstrap-server 192.168.10.30:9092,192.168.10.31:9092,192.168.10.32:9092 --topic target

**5、启动kafkaStreaming程序：**

[root@hadoop0 spark-2.1.1-bin-hadoop2.7]# bin/spark-submit --class com.m.jd.staming.KafkaStreaming /opt/spark-jar/kafkastreaming-jar-with-dependencies.jar

**程序运行部分结果如下：**

[root@hadoop0 kafka]# bin/kafka-console-producer.sh --broker-list 192.168.10.30:9092,192.168.10.31:9092,192.168.10.32:9092 --topic source
    >hello
    >hello spark
    >hello spark
    >haha
    >shuishui
    >ss
    >

[root@hadoop0 kafka]# bin/kafka-console-consumer.sh --bootstrap-server 192.168.10.30:9092,192.168.10.31:9092,192.168.10.32:9092 --topic target
    >>>>:hello
    >>>>:hello spark
    >>>>:hello spark
    >>>>:haha
    >>>>:shuishui
    >>>>:ss

**kafkaStreaming程序运行部分打印日志：**

>>>>:ss
    source 0 3 3
    source 1 2 3
    source 0 3 3
    source 1 3 3
    source 0 3 3
    source 1 3 3

上述日志对应：

${o.topic} ${o.partition} ${o.fromOffset} ${o.untilOffset}

--------------------

**拓展思考：**

**1、KafkaUtils.createDirectStream() 和 KafkaUtils.createStream()这两个方法的区别和底层实现？**

**2、上面两种方式下，Spark Streaming集成Kafka时如何保证数据不丢失，不重复消费？**

**3、上面两张方式下，Spark的partition和Kafka的partition有什么区别或者联系？**

**注意:**

> 在Spark Streaming中，目前官方推荐的方式是createDirectStream方式，但是这种方式就需要我们自己去管理offset，只要将 output 操作和保存 offsets 操作封装成一个原子操作。

//如果没有初始化偏移量或者当前的偏移量不存在任何服务器上，可以使用这个配置属性
        //可以使用这个配置，latest自动重置偏移量为最新的偏移量
        "auto.offset.reset" -> "latest",
        //如果是true，则这个消费者的偏移量会在后台自动提交
        "enable.auto.commit" -> (false: java.lang.Boolean)

参考文章：  
[Sparak-Streaming基于Offset消费Kafka数据][Sparak-Streaming_Offset_Kafka]

官方集成指南：  
[http://spark.apache.org/docs/latest/streaming-kafka-integration.html][http_spark.apache.org_docs_latest_streaming-kafka-integration.html]

[70]: /images/20220518/40d813a14ca54b0cb975a140f1bf40a1.png
[Kafka]: https://blog.csdn.net/u012834750/article/details/80821476
[Sparak-Streaming_Offset_Kafka]: http://www.itkeyword.com/doc/8350083418638114967/spark
[http_spark.apache.org_docs_latest_streaming-kafka-integration.html]: http://spark.apache.org/docs/latest/streaming-kafka-integration.html