Map[String, Seq[String]]
 
val queryStringMap = request.queryString
 
获取第一个参数值


  def getString(map: Map[String, Seq[String]],name:String):String = {
    if(map==null || name==null){
      return null
    }
    val values = map.get(name).getOrElse(null)
    if(values==null || values.isEmpty){
      return null
    }
    return values(0)
  }

  def getString2(map: Map[String, Seq[String]],name:String):String = {
    if(map==null || name==null){
      return null
    }
    val value = map.get(name).filter(_.nonEmpty).map(_(0)).getOrElse(null)
    return value
  }

  def getString3(map: Map[String, Seq[String]],name:String):Option[String] = {
    if(map==null || name==null){
      return null
    }
    val value = map.get(name).filter(_.nonEmpty).map(_(0))
    return value
  }
  
val map = Map("a"->Seq(),"b"->Seq("1","2"))


需要把为空的过滤掉
java.lang.IndexOutOfBoundsException: 0