Structure Streaming-通过 Batch 模式创建 Kafka 工作流

墨蓝 2023-02-20 03:17 59阅读 0赞

这种模式一般需要设置消费的其实偏移量和结束偏移量, 如果不设置 checkpoint 的情况下, 默 认起始偏移量 earliest, 结束偏移量为 latest.  
该模式为一次性作业(批处理), 而非持续性的处理数据.

import org.apache.spark.sql.SparkSession
    
    object Kafkabatch { 
      def main(args: Array[String]): Unit = { 
        val spark = SparkSession
          .builder()
          .master("local[*]")
          .appName("KafkaSource")
          .getOrCreate()
        import spark.implicits._
    
        val df = spark.read
          .format("kafka")
          .option("kafka.bootstrap.servers","hadoop102:9092,hadoop103:9092,hadoop104:9092")
          .option("subscribe","topic1")
          .option("startingOffsets", "earliest")
          .option("endingOffsets", "latest")
          .load
          // .select("value")
            .selectExpr("cast(value as string)")
            .as[String]
            .flatMap(_.split(" "))
            .groupBy("value")
            .count()
    
        df.write
          .format("console")
          .option("truncate",false)
          .save()
      }
    
    }

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一次性读完

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