class FtpShow(spark: SparkSession, map: Map[String, String]) {  private val path = map(FtpOptions.PATH).stripPrefix("./")  private val username = map(FtpOptions.USERNAME)  private val passwd = map(FtpOptions.PASSWORD)  private val host = map(FtpOptions.HOST)  private val port = map.getOrElse(FtpOptions.PORT, "21")  def getSampleData: String = {    val ftpUri = s"ftp://${username}:${passwd}@${host}:${port}/${path}"    spark.sparkContext      .wholeTextFiles(ftpUri)      .flatMap(s => s._2.split("\n"))      .take(DBShow.Num)      .mkString("\n")  }}

这里读取ftp文件的时候我们采用了sc.wholeTextFiles() 方法，若使用textFile() 方法，则会报错“java.io.IOException: Seek not supported”，ftp 的 InputStream 不支持seek(long:Long) 方法