iconmapper.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: IconMapper.java,v 1.4 2001/05/07 12:37:22 kunugi Exp $
**
** Copyright (c) 2000-2001 Jeff Gay
** on behalf of ICEMail.org <http://www.icemail.org>
** Copyright (c) 1998-2000 by Timothy Gerard Endres
** 
** This program is free software.
** 
** You may redistribute it and/or modify it under the terms of the GNU
** General Public License as published by the Free Software Foundation.
** Version 2 of the license should be included with this distribution in
** the file LICENSE, as well as License.html. If the license is not
** included with this distribution, you may find a copy at the FSF web
** site at 'www.gnu.org' or 'www.fsf.org', or you may write to the
** Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139 USA.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
** 
*/

package org.icemail.mail;

import java.awt.Image;

import java.io.IOException;

import java.util.Hashtable;

import javax.activation.CommandObject;
import javax.activation.DataHandler;
import javax.activation.MimeType;
import javax.activation.MimeTypeParseException;

import javax.swing.ImageIcon;

import org.icemail.Package;

import org.icemail.util.AWTUtilities;


/**
 * Class IconMapper implements a CommandObject for the Java Activation Framework.
 * IconMapper tries to become (load) the appropriate icon of the underlying datahandler.
 * <p>
 * The only verb supported is "view", becoming the appropriate icon for display.
 * And as you've already guessed, allows the mapper to be displayed.
 *
 * @see QuickViewer.getMailcapIcon()
 */
public class IconMapper
  extends ImageIcon
  implements CommandObject
{
  private static final int Debug_ = Package.DEBUG ? Package.getLevel( "IconMapper" ) : 0;

  private static Hashtable ImageCache_ = new Hashtable();

  private static String[]  Paths_ =
    { "/", "/images/mime/", "/org/icemail/mail/images/mime/", };


  /**
   * Default constructor.
   */
  public
  IconMapper() {
    super();
  }

  /**
   * Initialize the command object from the data handler as described by the verb.
   * <p>
   * Implements CommandObject.setCommandContext().
   * <p>
   * @param verb the command from the activation framework
   * @param dh the datahandler containing the data contents and type
   * @see javax.activation.CommandObject
   */
  public void
  setCommandContext( String verb, DataHandler dh ) throws IOException {
    setIconImage( dh.getContentType() );
  }

  /**
   * Set the icon (IconMapper) appropriately by the given contentType.
   *
   * @param contentType the content type of the underlying data handler
   */
  private void
  setIconImage( String contentType ) {
    if ( Package.DEBUG && Package.isTraceable( "IconMapper" ) ) {
      System.out.println( "IconMapper.setIconImage(s): " + contentType );
    }

    Image iconImg = null;

    if ( contentType != null )
    try {
      MimeType mime = new MimeType( contentType );

      iconImg = (Image)IconMapper.ImageCache_.get( mime.getBaseType() );

      if ( Package.DEBUG && Debug_ > 0 ) {
        System.err.println( "IconMapper: Cached? '" + mime.getBaseType() +
                            "'  = '" + (iconImg==null?"NO":"YES") );
      }

      if ( iconImg == null ) {
        iconImg = this.locateIconImage( this.getBaseName( mime ) );

        if ( iconImg != null )
          IconMapper.ImageCache_.put( mime.getBaseType(), iconImg );

        if ( Package.DEBUG && Debug_ > 0 ) {
          System.err.println( "IconMapper: Located '" + mime.getBaseType() +
                              "'  = '" + iconImg );
        }
      }

      if ( iconImg == null ) {
        iconImg = (Image)IconMapper.ImageCache_.get( mime.getPrimaryType() );

        if ( Package.DEBUG && Debug_ > 0 ) {
          System.err.println( "IconMapper: Cached? '" + mime.getPrimaryType() +
                              "'  = '" + (iconImg==null?"NO":"YES") );
        }
      }

      if ( iconImg == null ) {
        iconImg = this.locateIconImage( this.getPrimaryName( mime ) );

        if ( iconImg != null )
          IconMapper.ImageCache_.put( mime.getPrimaryType(), iconImg );

        if ( Package.DEBUG && Debug_ > 0 ) {
          System.err.println( "IconMapper: Located '" + mime.getPrimaryType() +
                              "'  = '" + iconImg );
        }
      }

      if ( iconImg == null ) {
        String unknownType = "unknown/unknown";
        String unknownName = "unknown.unknown.gif";

        iconImg = (Image)IconMapper.ImageCache_.get( unknownType );

        if ( Package.DEBUG && Debug_ > 0 ) {
          System.err.println( "IconMapper: Cached? '" + unknownType +
                              "'  = '" + (iconImg==null?"NO":"YES") );
        }

        if ( iconImg == null ) {
          iconImg = this.locateIconImage( unknownName );
          if ( iconImg != null )
            IconMapper.ImageCache_.put( unknownType, iconImg );

          if ( Package.DEBUG && Debug_ > 0 ) {
            System.err.println( "IconMapper: Located '" + unknownType +
                                "'  = '" + iconImg );
          }
        }

        if ( iconImg != null ) {
          IconMapper.ImageCache_.put( mime.getBaseType(), iconImg );
        }
      }
    } catch ( MimeTypeParseException ex ) { }

    this.setImage( iconImg );
  }

  private Image
  locateIconImage( String iconName ) {
    Image result = null;

    StringBuffer buf = new StringBuffer();

    for ( int pi = 0; result == null && pi < IconMapper.Paths_.length; ++pi ) {
      try {
        buf.setLength(0);
        buf.append( IconMapper.Paths_[ pi ] );
        buf.append( iconName );

        result = AWTUtilities.getImageResource( buf.toString() );
      } catch ( IOException ex ) { }
    }

    return result;
  }

  private String
  getPrimaryName( MimeType mime ) {
    StringBuffer buf = new StringBuffer();
    buf.append( mime.getPrimaryType() );
    buf.append( ".gif" );
    return buf.toString();
  }

  private String
  getBaseName( MimeType mime ) {
    StringBuffer buf = new StringBuffer();
    buf.append( mime.getPrimaryType() );
    buf.append( "." );
    buf.append( mime.getSubType() );
    buf.append( ".gif" );
    return buf.toString();
  }
}