com.taka_2.ftp.command
インタフェース 
FTPCommand
クラス 
CommandChdir
CommandChmod
CommandDelete
CommandHelp
CommandList
CommandMkdir
CommandNoop
CommandPass
CommandPort
CommandPwd
CommandQuit
CommandReady
CommandRenameFrom
CommandRenameTo
CommandRetr
CommandRmdir
CommandStore
CommandSystem
CommandTransfer
CommandType
CommandUser
FTPCommandAdapter