Knowledge Base Nr: 00220 LiveCamServer.java - http://www.swe-kaiser.de

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java: implementation of a socket server.
starts new processes and communicates with them.

  
//****************************************************************************
//* Imports                                                                  *
//****************************************************************************

import    java.net.*;
import    java.io.*;
import    java.lang.*;

//****************************************************************************
//* LiveCamServer                                                             *
//****************************************************************************

public class
LiveCamServer
extends Thread
{

//****************************************************************************
//* Constants                                                                *
//****************************************************************************

  public static final int     TELNET_PORT = 4711;

//****************************************************************************
//* Variables                                                                *
//****************************************************************************

  protected ServerSocket    listener;

//****************************************************************************
//* main                                                                     *
//****************************************************************************

  public static void
  main( String args[] )
  {
    new LiveCamServer();
  }

//****************************************************************************
//* fail                                                                     *
//****************************************************************************

  public static void
  fail( Exception e, String msg )
  {
    System.err.println( msg + "." + e );
    System.exit( 1 );
  }

//****************************************************************************
//* Constructor                                                              *
//****************************************************************************

  public
  LiveCamServer()
  {
    //  Try and create the socket...
    try
    {
      listener = new ServerSocket( TELNET_PORT, 5 );
    }
    catch ( IOException e )
    {
      fail( e, "Could not start LiveCam server" );
    }

    //  Show something to the user...
    System.out.println( "LiveCam server started" );

    //  Start up the thread...
    start();
  }

//****************************************************************************
//* run                                                                      *
//****************************************************************************

  public void
  run()
  {
    try
    {
      while ( true )
      {
        Socket client = listener.accept();
        System.out.println( "Accepted client..." );
        LiveCamThread c = new LiveCamThread( client );
      }
    }
    catch ( IOException e )
    {
      fail( e, "Unable to accept incoming client connection" );
    }
  }
}

//****************************************************************************
//* LiveCamThread                                                             *
//****************************************************************************

class
LiveCamThread
extends Thread
{

//****************************************************************************
//* Variables                                                                *
//****************************************************************************

  protected Socket        sClient;
  protected BufferedReader    disIn;
  protected PrintWriter     psOut;

//****************************************************************************
//* Constructor                                                              *
//****************************************************************************

  public
  LiveCamThread( Socket client )
  {
    try
    {
      //  Save a copy of our client socket...
      sClient = client;

      //  Don't cross the streams!
      disIn = new BufferedReader( new InputStreamReader( client.getInputStream() ) );
      psOut = new PrintWriter( client.getOutputStream(), true );

      //  Start up the client...
      start();
    }
    catch ( IOException e )
    {
      try
      {
        client.close();
      }
      catch ( IOException ioe )
      {
        System.err.println( "Error creating streams: " + ioe );
      }
    }
  }

//****************************************************************************
//* run                                                                      *
//****************************************************************************

  public void run()
  {
    String  cmd = null, res="";
    int n = 0;

    System.out.println( "Running client..." );

    Process grabber = null;

    try
    {
      grabber = Runtime.getRuntime().exec("e:/MyStuff/JavaCam.exe e:/projects/internet/my_home/images/k_images/livecam/javacam.bmp 4 0 217 19");
      BufferedReader grabberIn = new BufferedReader(  new InputStreamReader( grabber.getInputStream() ) );
      PrintWriter grabberOut = new PrintWriter( grabber.getOutputStream(), true );

      while ( true )
      {
        cmd = disIn.readLine();
        if (cmd == null)
          break;

        System.out.println( "client request: <" + cmd + ">");

        if (cmd.indexOf("Switch") >= 0)
        {
          Process switcher = Runtime.getRuntime().exec("\"E:/projects/msvc60/CControlIF/Debug/CControlIF.exe\" " + cmd);
          try { switcher.waitFor(); } catch(InterruptedException e) { }

          psOut.println(cmd + ": ok!");
        }
        else if (cmd.indexOf("GetPic") >= 0)
        {
          String param = cmd.substring(cmd.indexOf(" "));

          grabberOut.println(param);
          res = grabberIn.readLine();

          Process converter = Runtime.getRuntime().exec("\"c:/programme/thumbnailer/THUMB5\" /h /f e:/projects/internet/my_home/images/k_images/livecam/javacam.bmp e:/projects/internet/my_home/images/k_images/livecam/javacam.jpg");
          try { converter.waitFor(); } catch(InterruptedException e) { }

          psOut.println("Grabber: " + res);
        }
        else
        {
          psOut.println("Unknown command!");
        }

        if (psOut.checkError())
        {
          System.err.println("checkError() == true");
          break;
        }
      }
    }
    catch ( IOException e )
    {
       System.err.println( "Error in while loop: " + e );
    }

    finally
    {
      try
      {
        if (grabber != null)
          grabber.destroy();

        sClient.close();
        System.err.println( "closing client socket");
      }
      catch ( IOException ioe )
      {
        System.err.println( "Error closing client socket: " + ioe );
      }
    }

    System.out.println ( "thread finished!" );
  }

}