mhmessage.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: MHMessage.java,v 1.4 2001/05/07 12:38:11 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.javamail.mh;

import java.lang.String;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;

import java.util.Date;
import java.util.Enumeration;

import javax.mail.Address;
import javax.mail.Flags;
import javax.mail.Message;
import javax.mail.MessagingException;

import javax.mail.internet.MimeMessage;
import javax.mail.internet.InternetHeaders;

import javax.activation.DataHandler;

/**
 * Class MHMessage implements a "lazy" version of MimeMessage, instantiating
 * the message components only when necessary.
 * <p>
 * Simple analysis of MimeMessage access methods revealed that all access
 * boils down to accessing the headers or contents of the message, so
 * this implementation catches those access points and loads only what is
 * needed. Of course, the first load is immediately because headers need to
 * be obtained. However, the contents need not be in memory,
 * saving LOTS of memory when messages have attachments.
 *
 * @see javax.mail.internet.MimeMessage
 */
public class MHMessage
  extends MimeMessage
{
  /**
   * Instantiates a "lazy" message; empty of course.
   *
   * @param folder the folder of creation
   * @param msgnum the message number
   */
  public
  MHMessage( MHFolder folder, int msgnum ) {
    super( folder, msgnum );
  }

  /**
   * Intantiates a full populated message from the input stream.
   * <p>
   * It's private to keep others from instantiating a message completely.
   * This constructor is called only when the contents need to be
   * brought into memory; giving us access to the protected contents.
   *
   * @param folder the folder of creation
   * @param in     the input stream from which to load the contents of the message
   * @param msgnum the message number
   * @exception MessagingException the message could not be instantiated from the stream contents
   */
  private
  MHMessage( MHFolder folder, InputStream in, int msgnum )
  throws MessagingException {
    super( folder, in, msgnum );
  }

//------------------------------------------------------------
// over-loading of MimeMessage access methods

  public Enumeration
  getAllHeaderLines()
  throws MessagingException {
//    System.err.println( "MHMessage.getAllHeaderLines()" );
    loadHeaders();
    return super.getAllHeaderLines();
  }

  public Enumeration
  getAllHeaders()
  throws MessagingException {
//    System.err.println( "MHMessage.getAllHeaders()" );
    loadHeaders();
    return super.getAllHeaders();
  }

  public Address[] getAllRecipients()
  throws MessagingException {
//    System.err.println( "MHMessage.getAllRecipients()" );
    return super.getAllRecipients();
  }

  public Object getContent()
  throws IOException, MessagingException {
//    System.err.println( "MHMessage.getContent()" );
    return super.getContent();
  }

  public String getContentID()
  throws MessagingException {
//    System.err.println( "MHMessage.getContentID()" );
    return super.getContentID();
  }

  public String[] getContentLanguage()
  throws MessagingException {
//    System.err.println( "MHMessage.getContentLanguage()" );
    return super.getContentLanguage();
  }

  public String getContentMD5()
  throws MessagingException {
//    System.err.println( "MHMessage.getContentMD5()" );
    return super.getContentMD5();
  }

  protected InputStream getContentStream()
  throws MessagingException {
//    System.err.println( "MHMessage.getContentStream()" );
    loadContent();
    return super.getContentStream();
  }

  public String getContentType()
  throws MessagingException {
//    System.err.println( "MHMessage.getContentType()" );
    return super.getContentType();
  }

  public DataHandler getDataHandler()
  throws MessagingException {
//    System.err.println( "MHMessage.getDataHandler()" );
    return super.getDataHandler();
  }

  public String getDescription()
  throws MessagingException {
//    System.err.println( "MHMessage.getDescription()" );
    return super.getDescription();
  }

  public String getDisposition()
  throws MessagingException {
//    System.err.println( "MHMessage.getDisposition()" );
    return super.getDisposition();
  }

  public String getEncoding()
  throws MessagingException {
//    System.err.println( "MHMessage.getEncoding()" );
    return super.getEncoding();
  }

  public String getFileName()
  throws MessagingException {
//    System.err.println( "MHMessage.getFileName()" );
    return super.getFileName();
  }

  public Flags getFlags()
  throws MessagingException {
//    System.err.println( "MHMessage.getFlags()" );
    return super.getFlags();
  }

  public Address[] getFrom()
  throws MessagingException {
//    System.err.println( "MHMessage.getFrom()" );
    return super.getFrom();
  }

  public String[] getHeader(String name)
  throws MessagingException {
//    System.err.println( "MHMessage.getHeader( S )" );
    loadHeaders();
    return super.headers.getHeader( name );
  }

  public String getHeader(String name, String delimiter)
  throws MessagingException {
//    System.err.println( "MHMessage.getHeader( S, S )" );
    loadHeaders();
    return super.headers.getHeader( name, delimiter );
  }
  
  public InputStream getInputStream()
  throws IOException, MessagingException {
//    System.err.println( "MHMessage.getInputStream()" );
    return super.getInputStream();
  }

  public int getLineCount()
  throws MessagingException {
//    System.err.println( "MHMessage.getLineCount()" );
    return super.getLineCount();
  }

  public Enumeration getMatchingHeaderLines(String[] names)
  throws MessagingException {
//    System.err.println( "MHMessage.getMatchingHeaderLines()" );
    return super.getMatchingHeaderLines( names );
  }

  public Enumeration getMatchingHeaders(String[] names)
  throws MessagingException {
//    System.err.println( "MHMessage.getMatchingHeaders()" );
    return super.getMatchingHeaders( names );
  }

  public String getMessageID()
  throws MessagingException {
//    System.err.println( "MHMessage.getMessageID()" );
    return super.getMessageID();
  }

  public Enumeration getNonMatchingHeaderLines(String[] names)
  throws MessagingException {
//    System.err.println( "MHMessage.getNonMatchingHeaderLines()" );
    return super.getNonMatchingHeaderLines( names );
  }

  public Enumeration getNonMatchingHeaders(String[] names)
  throws MessagingException {
//    System.err.println( "MHMessage.getNonMatchingHeaders()" );
    return super.getNonMatchingHeaders( names );
  }

  public Date getReceivedDate()
  throws MessagingException {
//    System.err.println( "MHMessage.getReceivedDate()" );
    return super.getReceivedDate();
  }

  public Address[] getRecipients(Message.RecipientType type)
  throws MessagingException {
//    System.err.println( "MHMessage.getRecipients()" );
    return super.getRecipients( type );
  }

  public Address[] getReplyTo()
  throws MessagingException {
//    System.err.println( "MHMessage.getReplyTo()" );
    return super.getReplyTo();
  }

  public Date getSentDate()
  throws MessagingException {
//    System.err.println( "MHMessage.getSentDate()" );
    return super.getSentDate();
  }

  public int getSize()
  throws MessagingException {
//    System.err.println( "MHMessage.getSize()" );
    return super.getSize();
  }

  public String getSubject()
  throws MessagingException {
//    System.err.println( "MHMessage.getSubject()" );
    return super.getSubject();
  }

  public boolean isMimeType(String mimeType)
  throws MessagingException {
//    System.err.println( "MHMessage.isMimeType()" );
    return super.isMimeType( mimeType );
  }

  public boolean isSet(Flags.Flag flag)
  throws MessagingException {
//    System.err.println( "MHMessage.isSet()" );
    return super.isSet( flag );
  }

  public Message reply(boolean replyToAll)
  throws MessagingException {
//    System.err.println( "MHMessage.reply()" );
    return super.reply( replyToAll );
  }

//------------------------------------------------------------
//  load either headers or content from the file storage

  /**
   * Load only the headers for the message from the underlying file storage.
   * In this case, only the headers are parsed from the beginning of the file,
   * which is what the Java Mail manual says. Who knows...
   * <p>
   * The folder provides the full path to the file, which is named after the
   * message number. Figure that!
   */
  private void
  loadHeaders()
  throws MessagingException {
    if ( super.headers == null ) {
//      System.err.println( "MHMessage.loadHeaders()" );
      String xpath = ((MHFolder)super.folder).getMessagePath( super.msgnum );
      File   xfile = new File( xpath );
      try {
        FileInputStream xstream = new FileInputStream( xfile );
        super.headers = new InternetHeaders( xstream );
        xstream.close();
      }
      catch ( IOException xex ) {
        throw new MessagingException( xex.toString() );
      }
    }
  }

  /**
   * Load only the contents of the message from the underlying file storage.
   * In this case, a complete message is instantiated, of which the contents
   * are directly copied into this message. Shag me baby!
   * <p>
   * The folder provides the full path to the file, which is named after the
   * message number. Figure that!
   */
  private void
  loadContent()
  throws MessagingException {
    if ( super.content == null || super.content.length == 0 ) {
//      System.err.println( "MHMessage.loadContent()" );
      String xpath = ((MHFolder)super.folder).getMessagePath( super.msgnum );
      File   xfile = new File( xpath );
      try {
        FileInputStream xstream = new FileInputStream( xfile );
        MHMessage xmessage = new MHMessage( (MHFolder)super.folder, xstream, 777777 );
        xstream.close();
        super.content = new byte[ xmessage.content.length ];
        System.arraycopy( xmessage.content, 0, super.content, 0, xmessage.content.length );
      }
      catch ( IOException xex ) {
        throw new MessagingException( xex.toString() );
      }
    }
  }
}