dirclientapplet.java

Java程序设计技巧与开发实例附书源代码。

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.text.DecimalFormat;

public class DirClientApplet
    extends Applet
    implements ActionListener
{
   private Socket connection = null;
   private DataOutputStream out = null;
   private ObjectInputStream in = null;
   private List dirList = new List();
   private List fileList = new List();
   private TextField passwd = new TextField(10);
   private Label status = new Label("Click 'Connect' ...");
   private Button connect = new Button("Connect");
   private Button disconnect = new Button("Disconnect");
   private boolean connected = false;
   private DecimalFormat formatTool = new DecimalFormat("#,###");
   private String host = "localhost";
   public void init()
   {
      if (getParameter("host") != null)
      {
         host = getParameter("host");
      }
      Panel buttons = new Panel(new FlowLayout());
      buttons.add(new Label("Password: "));
      buttons.add(passwd);
      buttons.add(connect);
      buttons.add(disconnect);
      passwd.setEchoChar('*');
      Panel lists = new Panel(new BorderLayout());
      lists.add("North", new PanelBox(dirList, "Directories"));
      lists.add("Center", new PanelBox(fileList, "Files"));
      setLayout(new BorderLayout());
      add("North", new PanelBox(status, "Status"));
      add("Center", lists);
      add("South", buttons);
      connect.addActionListener(this);
      disconnect.addActionListener(this);
      dirList.addActionListener(this);
   }

   private void send(String cmd, String option) throws IOException
   {
      out.writeUTF(cmd);
      out.writeUTF(option);
      out.flush();
   }

   private void connect()
   {
      try
      {
         connection = new Socket(host, 8765);
         out = new DataOutputStream(connection.getOutputStream());
         in = new ObjectInputStream(connection.getInputStream());
         send("pass", "dirserver 1.0|" + passwd.getText());
         if (in.readUTF().equals("okay"))
         {
            status.setText("Authenticating ... connected");
            connected = true;
            showDirectory("pwd", "dummy");
         }
         else
         {
            status.setText("Authenticating ... REFUSED");
         }
      }
      catch (Exception ex)
      {
         status.setText("Error: " + ex);
      }
   }

   private void showDirectory(String cmd, String path)
   {
      try
      {
         send(cmd, path);
         path = in.readUTF();
         send("list", "dummy");
         FileInfo list[] = (FileInfo[]) in.readObject();
         dirList.removeAll();
         fileList.removeAll();
         dirList.add("..");
         long total = 0, nDirs = 0, nFiles = 0;
         for (int i = 0; i < list.length; i++)
         {
            if (list[i].isDirectory())
            {
               nDirs++;
               dirList.add(list[i].toString());
            }
            else
            {
               nFiles++;
               total += list[i].length();
               fileList.add(list[i].toString());
            }
         }
         status.setText(path + ", " + nDirs + " dirs, " + nFiles + " files, " +
                        formatTool.format(total) + " bytes]");
      }
      catch (Exception ex)
      {
         status.setText("Error: " + ex);
      }
   }

   public void stop()
   {
      if (connected)
      {
         try
         {
            send("bye", "dummy");
            dirList.removeAll();
            fileList.removeAll();
            in.close();
            out.close();
            connection.close();
         }
         catch (IOException ioe)
         {
            System.err.println("Error: " + ioe);
         }
         finally
         {
            connected = false;
            passwd.setText("");
            status.setText("Disconnected. Click 'Connect' ...");
         }
      }
   }

   public void actionPerformed(ActionEvent ae)
   {
      if ( (!connected) && (ae.getSource() == connect))
      {
         connect();
      }
      else if (connected && (ae.getSource() == disconnect))
      {
         stop();
      }
      else if (connected && (ae.getSource() == dirList))
      {
         showDirectory("chdir", dirList.getSelectedItem());
      }
   }

}