求助:类sun.net.*为何找不到?

chq791117

linux系统下,我的FTPManager.java:类为何找不到

import sun.net.TelnetInputStream;
import sun.net.ftp.FtpClient;

错误信息:

FTPManager.java:8: Class or interface `sun.net.TelnetOutputStream' not found in import.
import sun.net.TelnetOutputStream;
^
FTPManager.java:45: Type `FtpClient' not found in the declaration of the local variable `ftpClient'.
FtpClient ftpClient = new FtpClient();
^
FTPManager.java:65: Type `TelnetInputStream' not found in the declaration of the local variable `is'.
TelnetInputStream is = ftpClient.list();