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
}