backgammonbtconnection.java

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// Copyright (c) 2005 Sony Ericsson Mobile Communications AB
//
// This software is provided "AS IS," without a warranty of any kind. 
// ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, 
// INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A 
// PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. 
//
// THIS SOFTWARE IS COMPLEMENTARY OF JAYWAY AB (www.jayway.se)

package bluegammon.io;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import javax.bluetooth.RemoteDevice;
import javax.microedition.io.StreamConnection;

/**
 * Implementation of the interface <code>BackgammonConnection</code> for
 * bluetooth bearer.
 * @author Peter Andersson
 */
public class BackgammonBTConnection implements BackgammonConnection
{
  /** The service number of the game */
  protected static final String SERVICE_NBR = "1a88760401bac57a8806abc1ca900010";
  /** Bluetooth facade instance */
  protected static final BluetoothFacade BTFACADE = new BluetoothFacade();

  /** Flag indicating if server is actually awaiting a client */
  protected static boolean m_awaitingClient = false;
  /** Flag indicating if server denies connection once it gets a client */
  protected static boolean m_fakeServerClosed = false;
  /** Global server/client connection closed flag */
  protected static boolean m_closed = false;
  /** The server/client StreamConnection */
  protected volatile static StreamConnection m_connection;
  /** The server/client input stream */
  protected volatile static DataInputStream m_input;
  /** The server/client output stream */
  protected volatile static DataOutputStream m_output;
  
  /**
   * <p>
   * Waits for a client, the method blocks until client arrives
   * or IOException is thrown. The BT server cannot be interrupted - 
   * call <code>pretendServerClose</code> to emulate this. Any client
   * that connects after a call to <code>pretendServerClose</code> will
   * immediately be shutdown.
   * </p><p>
   * Disable this state by calling <code>waitForClient</code> again, which
   * will make the client accepted when it connects. Any call to
   * <code>waitForClient</code> during an already active client wait will
   * just set flags and return directly, as there must be another thread still
   * waiting a client generated by the first call to <code>waitForClient</code>.
   * <p>
   */
  public void waitForClient() throws IOException
  {
    synchronized(this)
    {
      if (m_awaitingClient && m_fakeServerClosed)
      {
        // Some other thread is still awaiting client,
        // just set flags and return from this call
        m_fakeServerClosed = false;
        return;
      }
      m_awaitingClient = true;
      m_fakeServerClosed = false;
    }
    try
    {
      // Start listening for client
      m_closed = false;
      m_connection = BTFACADE.waitForClient(SERVICE_NBR);
      m_input = m_connection.openDataInputStream();
      m_output = m_connection.openDataOutputStream();
    }
    catch (IOException ioe)
    {
      synchronized(this)
      {
        if (!m_closed && !m_fakeServerClosed)
        {
          // Not interested in exception if we're closed
          throw ioe;
        }
      }
    }
    finally
    {
      synchronized(this)
      {
        m_awaitingClient = false;
        // Close connections if some thread closed while we
        // were waiting for client
        if (m_fakeServerClosed)
        {
          close();
        }
      }
    }
  }

  public boolean connectClient(Object remote) throws IOException
  {
    synchronized(this)
    {
      m_closed = false;
    }
    boolean res = false;
    try
    {
      m_connection = BTFACADE.connect(SERVICE_NBR, (RemoteDevice) remote);
      if (m_connection != null)
      {
        m_input = m_connection.openDataInputStream();
        m_output = m_connection.openDataOutputStream();
        res = true;
      }
    }
    catch (IOException ioe)
    {
      synchronized(this)
      {
        if (!m_closed)
        {
          // Not interested in exception if we're closed
          throw ioe;
        }
      }
    }
    finally
    {
      synchronized(this)
      {
        if (m_closed)
        {
          close();
        }
      }
    }
    return res;
  }

  public StreamConnection getConnection() throws IOException
  {
    return m_connection;
  }

  public DataInputStream getInput()
  {
    return m_input;
  }

  public DataOutputStream getOutput()
  {
    return m_output;
  }
  
  /**
   * The BT server cannot be interrupted, so lets just
   * pretend we close the server. If the server gets a client while
   * in pretended closed mode, or when it time out,
   * we close connections for real.
   */
  public synchronized void pretendServerClose()
  {
    m_fakeServerClosed = true;
  }
  
  public synchronized boolean isAwaitingClient()
  {
    return m_awaitingClient;
  }

  public synchronized void close() throws IOException
  {
    IOException ioe = null;
    m_closed = true;
    // Close connection
    if (m_connection != null)
    {
      try
      {
        m_connection.close();
        m_connection = null;
      }
      catch (IOException e)
      {
        ioe = e;
      }
    }
    // Close input stream
    if (m_input != null)
    {
      try
      {
        m_input.close();
        m_input = null;
      }
      catch (IOException e)
      {
        ioe = e;
      }
    }
    // Close output stream
    if (m_output != null)
    {
      try
      {
        m_output.close();
        m_output = null;
      }
      catch (IOException e)
      {
        ioe = e;
      }
    }
    // Close server
    try
    {
      BTFACADE.closeServer(SERVICE_NBR);
      m_awaitingClient = false;
    }
    catch (IOException e)
    {
      ioe = e;
    }

    // Throw exception if we got any
    if (ioe != null)
    {
      throw ioe;
    }
  }
  
  public synchronized boolean isClosed()
  {
    return m_closed || m_fakeServerClosed;
  }
}