本文整理汇总了Scala中org.apache.parquet.hadoop.api.ReadSupport.ReadContext类的典型用法代码示例。如果您正苦于以下问题：Scala ReadContext类的具体用法？Scala ReadContext怎么用？Scala ReadContext使用的例子？那么, 这里精选的类代码示例或许可以为您提供帮助。
在下文中一共展示了ReadContext类的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Scala代码示例。
示例1: ScalaPBReadSupport
//设置package包名称以及导入依赖的类
package com.trueaccord.scalapb.parquet
import java.util
import com.trueaccord.scalapb.{GeneratedMessage, GeneratedMessageCompanion, Message}
import org.apache.hadoop.conf.Configuration
import org.apache.parquet.hadoop.api.{InitContext, ReadSupport}
import org.apache.parquet.hadoop.api.ReadSupport.ReadContext
import org.apache.parquet.io.api.{GroupConverter, RecordMaterializer}
import org.apache.parquet.schema.MessageType
class ScalaPBReadSupport[T <: GeneratedMessage with Message[T]] extends ReadSupport[T] {
override def prepareForRead(
configuration: Configuration,
keyValueMetaData: util.Map[String, String],
fileSchema: MessageType,
readContext: ReadContext): RecordMaterializer[T] = {
val protoClass = Option(keyValueMetaData.get(ScalaPBReadSupport.PB_CLASS)).getOrElse(throw new RuntimeException(s"Value for ${ScalaPBReadSupport.PB_CLASS} not found."))
val cmp = {
import scala.reflect.runtime.universe
val runtimeMirror = universe.runtimeMirror(getClass.getClassLoader)
val module = runtimeMirror.staticModule(protoClass)
val obj = runtimeMirror.reflectModule(module)
obj.instance.asInstanceOf[GeneratedMessageCompanion[T]]
}
new RecordMaterializer[T] {
val root = new ProtoMessageConverter[T](cmp, fileSchema, onEnd = _ => ())
override def getRootConverter: GroupConverter = root
override def getCurrentRecord: T = root.getCurrentRecord
}
}
override def init(context: InitContext): ReadContext = {
new ReadContext(context.getFileSchema)
}
}
object ScalaPBReadSupport {
val PB_CLASS = "parquet.scalapb.class"
}