Spark Avro序列化

import org.apache.avro.Schema

import org.apache.spark.sql.ForeachWriter

 

class AvroWriter(schema: Schema) extends ForeachWriter[Row] {

 

  var producer: KafkaProducer[Array[Byte], Array[Byte]] = _

 

  override def open(partitionId: Long, version: Long): Boolean = {

    val props = new Properties()

    props.put("bootstrap.servers", "your_kafka_broker_host:your_kafka_broker_port")

    props.put("key.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer")

    props.put("value.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer")

    producer = new KafkaProducer[Array[Byte], Array[Byte]](props)

    true

  }

 

  override def process(row: Row): Unit = {

    val record = new ProducerRecord[Array[Byte], Array[Byte]]("your_topic_name", serializeRow(row))

    producer.send(record)

  }

 

  override def close(errorOrNull: Throwable): Unit = {

    producer.close()

  }

 

  private def serializeRow(row: Row): Array[Byte] = {

    // 这里将 row 转换为 GenericRecord 并序列化为字节数组

    // 使用上面提到的方法将 schema 序列化为字节数组并传递给 KafkaProducer

    // ...

  }

 

  private def deserializeSchema(bytes: Array[Byte]): Schema = {

    new Schema.Parser().parse(bytes)

  }

 

}

 

 

 

 

 

serializeRow 方法可以根据 schema 将 Row 对象序列化为 Avro GenericRecord 对象,示例如下:

 

import org.apache.avro.Schema

import org.apache.avro.generic.GenericData

import org.apache.avro.generic.GenericRecord

import org.apache.spark.sql.Row

 

def serializeRow(row: Row, schema: Schema): GenericRecord = {

  val genericRecord = new GenericData.Record(schema)

  // 遍历 Row 中每个字段

  for (i <- 0 until row.size) {

    // 获取字段名和字段值

    val fieldName = schema.getFields.get(i).name()

    val fieldValue = row.get(i)

    // 根据字段类型设置 GenericRecord 中对应字段的值

    schema.getFields.get(i).schema().getType match {

      case Schema.Type.STRING => genericRecord.put(fieldName, fieldValue.asInstanceOf[String])

      case Schema.Type.INT => genericRecord.put(fieldName, fieldValue.asInstanceOf[Int])

      case Schema.Type.LONG => genericRecord.put(fieldName, fieldValue.asInstanceOf[Long])

      case Schema.Type.FLOAT => genericRecord.put(fieldName, fieldValue.asInstanceOf[Float])

      case Schema.Type.DOUBLE => genericRecord.put(fieldName, fieldValue.asInstanceOf[Double])

      case Schema.Type.BOOLEAN => genericRecord.put(fieldName, fieldValue.asInstanceOf[Boolean])

      case Schema.Type.ARRAY =>

        val fieldSchema = schema.getFields.get(i).schema().getElementType

        val genericArray = new GenericData.Array(fieldValue.asInstanceOf[Seq[Any]].size, fieldSchema)

        fieldValue.asInstanceOf[Seq[Any]].foreach { element =>

          genericArray.add(serializeField(element, fieldSchema))

        }

        genericRecord.put(fieldName, genericArray)

      // 处理其他类型,如 Union 类型、Map 类型等

      case _ => // TODO

    }

  }

  genericRecord

}

 

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