Kafka作为SparkStreaming的数据源
1、用法以及说明
在工作中需要引入Maven工件以及Spark-streaming-Kafka-0-8_2.11来使用,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。
两个核心类,KafkaUtils以及KafkaCluster
2、案例实操
需求:
通过SparkStreaming从Kafka读取数据,并将读取过来的数据做简单计算(WordCount),最终打印到控制台。
(1) 导入依赖
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming-kafka-0-8_2.11</artifactId>
<version>2.1.1</version>
</dependency>
(2)编写代码
import kafka.serializer.StringDecoder
import org.apache.kafka.clients.consumer.ConsumerConfig
import org.apache.spark.SparkConf
import org.apache.spark.storage.StorageLevel
import org.apache.spark.streaming.dstream.{DStream, ReceiverInputDStream}
import org.apache.spark.streaming.kafka.KafkaUtils
import org.apache.spark.streaming.{Seconds, StreamingContext}
object KafkaToSpark {
def main(args: Array[String]): Unit = {
//1.创建SparkConf对象
val sparkConf = new SparkConf().setMaster("local[*]").setAppName("App")
//2.创建StreamingContext对象
val ssc: StreamingContext = new StreamingContext(sparkConf,Seconds(5))
val kafkaParas= Map(
ConsumerConfig.GROUP_ID_CONFIG->"bigdata",
ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG->"org.apache.kafka.common.serialization.StringDeserializer",
ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG->"org.apache.kafka.common.serialization.StringDeserializer",
"zookeeper.connect"->"hadoop102:2181"
)
------"这里需要注意的是kafka的参数属性中设置连接的是zookeeper,如果版本较新的话用bootstrap.server连接Kafka"
//第一个参数是topic名称,第二个是副本数
val topics = Map(
"ssTopic"->3
)
//[String,String,StringDecoder,StringDecoder]
"这里的泛型信息必要要加上,否则会报错[String,String,StringDecoder,StringDecoder]"
val kafkaStream: ReceiverInputDStream[(String, String)] =
KafkaUtils.createStream[String,String,StringDecoder,StringDecoder](ssc,kafkaParas,topics,StorageLevel.MEMORY_ONLY)
val flatStream: DStream[String] = kafkaStream.flatMap {
case (k, v) => {
v.split(" ")
}
}
val wordCount: DStream[(String, Int)] = flatStream.map((_,1)).reduceByKey(_+_)
wordCount.print()
// 让采集器启动
ssc.start()
// drvier等待采集器的执行
ssc.awaitTermination()
}
}
查看Kafka的topic列表
bin/katopics.sh --zookeeper hadoop102:2181 --list
创建一个topic
bin/katopics.sh --zookeeper hadoop102:2181 --create --topic ssTopic --partitions 2 --replication-factor 2
创建一个控制面板的生产者,往指定的topic里生产消息
bin/kaconsole-producer.sh --broker-list hadoop102:9092 --topic ssTopic