Scala query string parser using Java Collections

parseUriParameters-using-java-collections.scala

import java.net.URLDecoder
import java.util.{ArrayList, HashMap, List, Map}
import scala.collection.JavaConversions._

/**
 * Parse the query string portion of a string containing a URI or URL.
 */
/**
 * Parse the query string portion of a string containing a URI or URL.
 */
def parseUriParameters(uri: String): Map[String, List[String]] = {
    val params = new HashMap[String, List[String]]()
    val parts = uri split "\\?"
    if (parts.length > 1) {
        val query = parts(1)
        query split "&" map { param =>
            val pair = param split "="
            val key = URLDecoder.decode(pair(0), "UTF-8")
            val value = pair.length match {
                case l if l > 1 => URLDecoder.decode(pair(1), "UTF-8")
                case _ => ""
            }
            val values = Option(params get key) match {
                case Some(values) => values

                case None =>
                    val v = new ArrayList[String]()
                    params.put(key, v)
                    v
            }
            values add value // NB: The value may be an empty string.
        }
    }
    params
}

Refactored this to be pure Scala

def parseUriParameters(uri: String): Map[String, Seq[String]] = {
    val parts = uri split "\\?"
    if (parts.length > 1) {
      val query = parts(1)
      val utf8 = "UTF-8"
      query.split("&").flatMap{queryString =>
        val fullQueryParam = queryString.split("=")
        val keyValues = fullQueryParam.headOption.flatMap(key => fullQueryParam.drop(1).headOption.map(value => URLDecoder.decode(key, utf8) -> URLDecoder.decode(value, utf8)))
        keyValues
      }.groupBy(_._1).mapValues(_.toVector.map(_._2))
    } else Map.empty
  }