com.databricks.spark.xml.util.XmlFile.scala Maven / Gradle / Ivy
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/*
* Copyright 2014 Databricks
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.databricks.spark.xml.util
import java.io.CharArrayWriter
import java.nio.charset.Charset
import javax.xml.stream.XMLOutputFactory
import scala.collection.Map
import com.databricks.spark.xml.parsers.StaxXmlGenerator
import com.databricks.spark.xml.{XmlOptions, XmlInputFormat}
import com.sun.xml.txw2.output.IndentingXMLStreamWriter
import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.io.{Text, LongWritable}
import org.apache.hadoop.io.compress.CompressionCodec
import org.apache.spark.rdd.RDD
import org.apache.spark.SparkContext
import org.apache.spark.sql.DataFrame
import org.apache.spark.sql.catalyst.util.CompressionCodecs
private[xml] object XmlFile {
val DEFAULT_INDENT = " "
def withCharset(
context: SparkContext,
location: String,
charset: String,
rowTag: String): RDD[String] = {
// This just checks the charset's validity early, to keep behavior
Charset.forName(charset)
val config = new Configuration(context.hadoopConfiguration)
config.set(XmlInputFormat.START_TAG_KEY, s"<$rowTag>")
config.set(XmlInputFormat.END_TAG_KEY, s"")
config.set(XmlInputFormat.ENCODING_KEY, charset)
context.newAPIHadoopFile(location,
classOf[XmlInputFormat],
classOf[LongWritable],
classOf[Text],
config).map { case (_, text) => text.toString }
}
/**
* Note that writing a XML file from [[DataFrame]] having a field
* [[org.apache.spark.sql.types.ArrayType]] with its element as nested array would have
* an additional nested field for the element. For example, the [[DataFrame]] having
* a field below,
*
* fieldA Array(Array(data1, data2))
*
* would produce a XML file below.
*
*
* - data1
*
*
* - data2
*
*
* Namely, roundtrip in writing and reading can end up in different schema structure.
*/
def saveAsXmlFile(
dataFrame: DataFrame,
path: String,
parameters: Map[String, String] = Map()): Unit = {
val options = XmlOptions(parameters.toMap)
val codec = Option(options.codec).map(CompressionCodecs.getCodecClassName)
// scalastyle:off classforname
val codecClass: Option[Class[_ <: CompressionCodec]] =
codec.map(Class.forName(_).asInstanceOf[Class[CompressionCodec]])
val rowSchema = dataFrame.schema
val indent = XmlFile.DEFAULT_INDENT
// Allow a root tag to be like "rootTag foo='bar'"
// This is hacky; won't deal correctly with spaces in attributes, but want
// to make this at least work for simple cases without much complication
val rootTagTokens = options.rootTag.split(" ")
val rootElementName = rootTagTokens.head
val rootAttributes: Map[String, String] =
if (rootTagTokens.length > 1) {
rootTagTokens.tail.map { kv =>
val Array(k, v) = kv.split("=")
k -> v.replaceAll("['\"]", "")
}.toMap
} else {
Map.empty
}
val declaration = options.declaration
val xmlRDD = dataFrame.rdd.mapPartitions { iter =>
val factory = XMLOutputFactory.newInstance()
val writer = new CharArrayWriter()
val xmlWriter = factory.createXMLStreamWriter(writer)
val indentingXmlWriter = new IndentingXMLStreamWriter(xmlWriter)
indentingXmlWriter.setIndentStep(indent)
new Iterator[String] {
var firstRow: Boolean = true
var lastRow: Boolean = true
override def hasNext: Boolean = iter.hasNext || firstRow || lastRow
override def next(): String = {
if (iter.nonEmpty) {
if (firstRow) {
if (declaration != null && declaration.nonEmpty) {
indentingXmlWriter.writeProcessingInstruction("xml", declaration)
indentingXmlWriter.writeCharacters("\n")
}
indentingXmlWriter.writeStartElement(rootElementName)
rootAttributes.foreach { case (k, v) =>
indentingXmlWriter.writeAttribute(k, v)
}
firstRow = false
}
val xml = {
StaxXmlGenerator(
rowSchema,
indentingXmlWriter,
options)(iter.next())
indentingXmlWriter.flush()
writer.toString
}
writer.reset()
xml
} else {
if (!firstRow) {
lastRow = false
indentingXmlWriter.writeEndElement()
indentingXmlWriter.close()
writer.toString
} else {
// This means the iterator was initially empty.
firstRow = false
lastRow = false
""
}
}
}
}
}
codecClass match {
case None => xmlRDD.saveAsTextFile(path)
case Some(codec) => xmlRDD.saveAsTextFile(path, codec)
}
}
}