JAVA源代码如下：
package jdeveloper.ftp;import sun.net.ftp.*;import sun.net.*;import java.awt.*;import java.awt.event.*;import java.applet.*;import java.io.*;public class FtpApplet extends Applet{FtpClient aftp;DataOutputStream outputs ;TelnetInputStream ins;TelnetOutputStream outs;TextArea lsArea;Label    LblPrompt;Button   BtnConn;Button   BtnClose;TextField  TxtUID;TextField  TxtPWD;TextField  TxtHost;int ch;public String a="没有连接主机";        String hostname="";public void init () {setBackground(Color.white);setLayout(new GridBagLayout());GridBagConstraints GBC = new GridBagConstraints();LblPrompt = new Label("没有连接主机");LblPrompt.setAlignment(Label.LEFT);BtnConn = new Button("连接");BtnClose = new Button("断开");BtnClose.enable(false);TxtUID = new TextField("",15);TxtPWD = new TextField("",15);TxtPWD.setEchoCharacter('*');TxtHost = new TextField("",20);Label LblUID = new Label("User ID:");Label LblPWD = new Label("PWD:");Label LblHost = new Label("Host:");lsArea = new TextArea(30,80);lsArea.setEditable(false);GBC.gridwidth= GridBagConstraints.REMAINDER;GBC.fill     = GridBagConstraints.HORIZONTAL;((GridBagLayout)getLayout()).setConstraints(LblPrompt,GBC);add(LblPrompt);GBC.gridwidth=1;((GridBagLayout)getLayout()).setConstraints(LblHost,GBC);add(LblHost);GBC.gridwidth=GridBagConstraints.REMAINDER;((GridBagLayout)getLayout()).setConstraints(TxtHost,GBC);add(TxtHost);GBC.gridwidth=1;((GridBagLayout)getLayout()).setConstraints(LblUID,GBC);add(LblUID);GBC.gridwidth=1;((GridBagLayout)getLayout()).setConstraints(TxtUID,GBC);add(TxtUID);GBC.gridwidth=1;((GridBagLayout)getLayout()).setConstraints(LblPWD,GBC);add(LblPWD);GBC.gridwidth=1;((GridBagLayout)getLayout()).setConstraints(TxtPWD,GBC);add(TxtPWD);GBC.gridwidth=1;GBC.weightx=2;((GridBagLayout)getLayout()).setConstraints(BtnConn,GBC);add(BtnConn);GBC.gridwidth=GridBagConstraints.REMAINDER;((GridBagLayout)getLayout()).setConstraints(BtnClose,GBC);add(BtnClose);GBC.gridwidth=GridBagConstraints.REMAINDER;GBC.fill     = GridBagConstraints.HORIZONTAL;((GridBagLayout)getLayout()).setConstraints(lsArea,GBC);add(lsArea);        }public boolean connect(String hostname, String uid,String pwd){                this.hostname = hostname;LblPrompt.setText("正在连接，请等待.....");try{  aftp =new FtpClient(hostname);  aftp.login(uid,pwd);  aftp.binary();  showFileContents();}catch(FtpLoginException e){a="无权限与主机:"+hostname+"连接!";LblPrompt.setText(a);return false;}catch (IOException e){a="连接主机:"+hostname+"失败!";LblPrompt.setText(a);return false;}catch(SecurityException e){a="无权限与主机:"+hostname+"连接!";LblPrompt.setText(a);return false;}LblPrompt.setText("连接主机:"+hostname+"成功!");return true;}public void stop(){try{aftp.closeServer();}catch(IOException e){}}public void paint(Graphics g){}public boolean action(Event evt,Object obj){if (evt.target == BtnConn){LblPrompt.setText("正在连接，请等待.....");if (connect(TxtHost.getText(),TxtUID.getText(),TxtPWD.getText())){BtnConn.setEnabled(false);BtnClose.setEnabled(true);}return true;}if (evt.target == BtnClose){stop();BtnConn.enable(true);BtnClose.enable(false);LblPrompt.setText("与主机"+hostname+"连接已断开!");return true;}return super.action(evt,obj);}public boolean sendFile(String filepathname){boolean result=true;if (aftp != null){LblPrompt.setText("正在粘贴文件,请耐心等待....");String  contentperline;try{a="粘贴成功!";String fg =new  String("\\");int index = filepathname.lastIndexOf(fg);String filename = filepathname.substring(index+1);File localFile ;localFile = new File(filepathname) ;RandomAccessFile sendFile = new RandomAccessFile(filepathname,"r");//sendFile.seek(0);outs = aftp.put(filename);outputs = new DataOutputStream(outs);while (sendFile.getFilePointer() < sendFile.length() ){  ch = sendFile.read();  outputs.write(ch);}outs.close();sendFile.close();}catch(IOException e){  a = "粘贴失败!";  result = false ;}LblPrompt.setText(a);showFileContents();}else{result = false;}return result;}public void showFileContents(){StringBuffer buf = new StringBuffer();lsArea.setText("");try{ins= aftp.list();while ((ch=ins.read())>=0){  buf.append((char)ch);}    lsArea.appendText(buf.toString());ins.close();        }catch(IOException e){}}        public static void main(String args[]){             Frame f = new Frame("FTP Client");             f.addWindowListener(new WindowAdapter(){               public void windowClosing(WindowEvent e){                   System.exit(0);               }             });             FtpApplet ftp = new  FtpApplet();             ftp.init();             ftp.start();             f.add(ftp);             f.pack();             f.setVisible(true);        }}
提示：   自己解开rt.jar，反编其代码，如sun.net.ftp.FtpClient等。
下载： ftp.jar运行： java -jar ftp.jar