dirthread.java

Java程序设计技巧与开发实例附书源代码。

import java.util.*;
import java.io.*;
import java.net.*;

public class DirThread
    extends Thread
{
   private ObjectOutputStream out = null;
   private DataInputStream in = null;
   private Socket sock = null;
   private boolean running = false;
   private File currentPath = new File(System.getProperty("user.dir"));

   public DirThread(Socket _sock)
   {
      System.out.println("Starting directory connection ...");
      sock = _sock;
      try
      {
         in = new DataInputStream(sock.getInputStream());
         out = new ObjectOutputStream(sock.getOutputStream());
         running = true;
         start();
      }
      catch (IOException ioe)
      {
         System.err.println("Error setting up streams: " + ioe);
      }
   }

   public void run()
   {

      authenticate();
      while (running)
      {
         try
         {
            processCommand(in.readUTF(), in.readUTF());
         }
         catch (IOException ioe)
         {
            hangup();
         }
      }
   }

   private void send(File list[]) throws IOException
   {  FileInfo info[] = new FileInfo[list.length];
      for (int i = 0; i < list.length; i++)
         info[i] = new FileInfo(list[i]);
      out.writeObject(info); out.flush(); 
   }


   private void send(String msg) throws IOException
   {
      out.writeUTF(msg);
      out.flush();
   }

   private void changeDirectory(String newDir) throws IOException
   {

      if ( (newDir.equals("..")) &&
          (currentPath.getParentFile() != null))
      {
         currentPath = currentPath.getParentFile();
      }
      else
      {
         File newPath = new File(newDir);
         if (newPath.exists() && newPath.isDirectory())
         {
            currentPath = newPath;
         }
      }
      send(currentPath.toString());
   }

   private void authenticate()
   {
      try
      {
         String cmd = in.readUTF();
         String passwd = in.readUTF();
         if (passwd.equals(DirServer.VERSION + "|" + DirServer.PASSWD))
         {
            send("okay");
         }
         else
         {
            send("error");
            hangup();
         }
      }
      catch (IOException ioe)
      {
         hangup();
      }
   }

   private void hangup()
   {
      try
      {
         System.out.println("Hanging up");
         in.close();
         out.close();
         sock.close();
      }
      catch (IOException ioe)
      {
         System.err.println("Error disconnecting: " + ioe);
      }
      finally
      {
         running = false;
      }
   }

   private void processCommand(String cmd, String option) throws IOException
   {
      if (cmd.equals("pwd"))
      {
         send(currentPath.toString());
      }
      else if (cmd.equals("chdir"))
      {
         changeDirectory(option);
      }
      else if (cmd.equals("list"))
      {
         send(currentPath.listFiles());
      }
      else
      {
         hangup();
      }
   }
}