dynaserver.java

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/*
 * Copyright 2000 by dreamBean Software,
 * All rights reserved.
 */
package com.dreambean.dynaserver;

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

/**
 *   A mini webserver that can be embedded in another application as a JavaBean. It can serve any file that is available from
 *   classloaders that are registered with it, including class-files.
 *
 *   Its primary purpose is to simplify dynamic class-loading in RMI. Create an instance of it, register a classloader 
 *   with your classes, start it, and you'll be able to let RMI-clients dynamically download classes from it.
 *
 *   Note: the use of the synchronized is mainly due to the thread synch. issues with the JVM spec
 *
 *   @author $Author: Rickard 謆erg ([e-mail])$
 *   @version $Revision: 1.0$
 */
public final class DynaServer
{
   // Constants -----------------------------------------------------
   /** 
    * List of ports to try during portscan
    * Try anonymous (0) if all else fails
    */
   public final String PORTS = "8080,8081,8082,80,81,82,0";
   
   /** 
    * Time out for server socket.
    */
   public final int SO_TIMEOUT = 10000; // ServerSocket timeout to allow it to check "running" flag
    
   // Attributes ----------------------------------------------------
   private ArrayList classLoaders = new ArrayList();
   private List requests = new ArrayList();
   
   private int port = 8080;
   private int backLog = 50; // Nr of requests to queue in ServerSocket. 50 is JDK default, so use that
   private boolean portScan = true; // If port is taken, try to scan for free ones
   private boolean debug = false; // The server shows some debugging info if this is true
   private int nrOfHandlers = 5; // Nr of request handlers
   
   private Properties mimeTypes = new Properties(); // The MIME type mapping
   
   private boolean running;
   
   // Static --------------------------------------------------------

   // Constructors --------------------------------------------------
   public DynaServer()
   {
      initMimetypes();
   }

   // Public --------------------------------------------------------
   public synchronized void setPort(int p) { port = p; }
   public synchronized int getPort() { return port; }
   
   public synchronized void setPortScan(boolean portScan) { this.portScan = portScan; }
   public synchronized boolean getPortScan() { return portScan; }
   
   public synchronized void setBackLog(int b) { backLog = b; }
   public synchronized int getBackLog() { return backLog; }
   
   public synchronized void setDebug(boolean d) { debug = d; }
   public synchronized boolean isDebug() { return debug; }

   public synchronized void setNrOfHandlers(int nrOfHandlers) { this.nrOfHandlers = nrOfHandlers; }
   public synchronized int getNrOfHandlers() { return nrOfHandlers; }
   
   public synchronized boolean isRunning() { return running; }
   
   public synchronized void start()
      throws IOException
   {
      if (isRunning())
         return;
         
      try
      {
         running = true;
         
         // Start socket listener
         new RequestListener();
         
         // Start request handlers
         for (int i = 0; i < nrOfHandlers; i++)
         {
            new RequestHandler();
         }
         
         initCodebase();
         
         debug("Started on port " + getPort());
      } catch (IOException e)
      {
         debug("Could not start on port " + getPort());
         throw e;
      }
   }
   
   public synchronized void stop()
   {
      // Close already accepted requests
      Iterator enum = requests.iterator();
      while (enum.hasNext())
      {
         try
         {
            Socket request = (Socket)enum.next();
            request.close();
         } catch (IOException e)
         {
            // Ignore
         }
      }
   
      // Change state to not running and notify handlers
      running = false;
      notifyAll();
      
      try
      {
         wait(SO_TIMEOUT); // Wait for listener to finish
      } catch (InterruptedException e)
      {
         // Ignore
      }
   }
   
   public synchronized void addClassLoader(ClassLoader cl)
   {
      ArrayList arr = (ArrayList)classLoaders.clone();
      arr.add(cl);
      classLoaders = arr;
   }
   
   public synchronized void removeClassLoader(ClassLoader cl)
   {
      ArrayList arr = (ArrayList)classLoaders.clone();
      arr.remove(cl);
      classLoaders = arr;
   }
   
   public synchronized Collection getClassLoaders()
   {
      return classLoaders;
   }
   

   // Package protected ---------------------------------------------
   synchronized void debug(String msg)
   {
      if (isDebug())
         System.out.println(msg);
   }
    
   // Protected -----------------------------------------------------
   
   /**
    * Returns the path to the class file obtained from
    * parsing the HTML header.
    */
   
   protected String getMimeType(String path)
   {
      String ext = path.substring(path.lastIndexOf(".")+1);
      String type = mimeTypes.getProperty(ext);
      if (type == null)
      {
         debug("No MIME-type registered for:"+ext);
         return "text/plain";
      }
      else
         return type;
   }
   
   protected synchronized void addRequest(Socket request)
   {
      requests.add(request);
      notifyAll();
   }
    
   protected synchronized Socket getRequest()
      throws IllegalStateException
   {
      while (requests.isEmpty() && isRunning())
      {
         try
         {
            wait();
         } catch (InterruptedException e)
         {
            // Ignore
         }
      }
      
      if (isRunning())
         return (Socket)requests.remove(0);
      else
         throw new IllegalStateException();   
   }
   
   // Private -------------------------------------------------------
   private void initCodebase()
   {
      // Compute codebase
      String host = System.getProperty("java.rmi.server.hostname");
      if (host ==null)
      {
         try
         {
            host = InetAddress.getLocalHost().getHostName(); 
         } catch (UnknownHostException e)
         {
            // Notify about problem, but ignore
            debug("Could not get hostname");
         }
      }
   
      String codebase = "http://"+host+":"+getPort()+"/";
   
      // Try setting codebase if not set, 
      // or if different from computed codebase (port may have changed because of port scanning!)
      String currentCodebase = System.getProperty("java.rmi.server.codebase");
      if (currentCodebase == null || !currentCodebase.equals(codebase))
      {
         System.setProperty("java.rmi.server.codebase", codebase);
         debug("Codebase set to "+codebase);
      }      
   }

   private void initMimetypes()
   {
      // Load the file mime.types into the mapping list
      try
      {
         InputStream in = getClass().getResourceAsStream("/mime.types");
         if (in != null)
            mimeTypes.load(in);
         else
      	   System.err.println("No mime-type mappings found!");   
      } catch (IOException e)
      {
         e.printStackTrace(System.err);
      }
   }
   
   // Inner classes -------------------------------------------------
   class RequestListener
      implements Runnable
   {
      ServerSocket serverSocket;
   
      RequestListener()
         throws IOException
      {
         try