mhfolder.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: MHFolder.java,v 1.5 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.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import java.util.Enumeration;
import java.util.Vector;

import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Header;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Store;

import javax.mail.internet.MimeMessage;


/**
 * The folder class implementing local disk storage for messages.
 */

public class MHFolder
  extends Folder
{
  public static final String    DELIM = "/";

  private boolean               debug_ = false;
  private int                   maxMsgNum_ = 0;

  private String                name_ = null;
  private String                path_ = null;

  private Vector                fileCache_ = null;
  private Vector                dirCache_ = null;
  private Vector                msgCache_ = null;


  /**
   * Constructor.
   */
  public
  MHFolder( Store store, String path, boolean debug ) {
    super( store );

    debug_ = debug;

    if ( debug_ )
      System.err.println( "NEW MHFolder: path = '" + path + "'" );


    if ( path == null || path.length() == 0 ) {
    // special case where store is opening the first folder
      path_ = ((MHStore)super.store).getPath();
    } else if ( path.endsWith( DELIM ) ) {
      path_ = path.substring( 0, path.length() );
    } else {
      path_ = path;
    }

    int xindex = path_.lastIndexOf( DELIM );

    if ( xindex < 0 ) {
      name_ = path_;
      path_ = "";
    } else {
      name_ = path_.substring( xindex + 1 );
      path_ = path_.substring( 0, xindex );
    }

    if ( debug_ ) {
      System.err.println( "NEW MHFolder: name = '" + name_ + "'" );
      System.err.println( "NEW MHFolder: path = '" + path_ + "'" );
    }
  }

  /**
   */
  public String
  getMessagePath( int msgnum ) {
    String xname = (String)fileCache_.elementAt( msgnum - 1 );
    return getFullName() + DELIM + xname;
  }

  /**
   * Returns the name of this folder.
   * <p>
   * Implementation of javax.mail.Folder.getName().
   */
  public String
  getName() {
    return name_;
  }

  /**
   * Returns the full name of this folder.
   * <p>
   * Implementation of javax.mail.Folder.getFullName().
   */
  public String
  getFullName() {
    if ( path_.length() == 0 )
      return name_;
    else
      return path_ + DELIM + name_;
  }

  /**
   * Returns the type of this folder.
   * <p>
   * Implementation of javax.mail.Folder.getType().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public int
  getType() throws MessagingException {
    return Folder.HOLDS_FOLDERS + Folder.HOLDS_MESSAGES;
  }

  /**
   * Return the open mode of this folder.
   * <p>
   * Implementation of javax.mail.Folder.getMode().
   */
  public int
  getMode() {
    return super.mode;
  }

  /**
   * Indicates whether this folder exists.
   * <p>
   * Implementation of javax.mail.Folder.exists().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public boolean
  exists() throws MessagingException {
    File xdir = new File( getFullName() );
    return xdir.exists();
  }

  /**
   * Indicates whether this folder contains new messages.
   * <p>
   * Implementation of javax.mail.Folder.hasNewMessages().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public boolean
  hasNewMessages() throws MessagingException {
    return false;
  }

  /**
   * Opens this folder.
   * <p>
   * Implementation of javax.mail.Folder.open().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public void
  open( int mode ) throws MessagingException
  {
    if ( debug_ )
      System.err.println( "open: '" + name_ + "' mode " + mode );

    checkCacheLoaded();

    super.mode = mode;
  }

  /**
   * Closes this folder.
   * <p>
   * Implementation of javax.mail.Folder.close().
   *
   * @param expunge if the folder is to be expunged before it is closed
   * @exception MessagingException if a messaging error occurred
   */
  public void
  close( boolean expunge ) throws MessagingException {
    if ( debug_ )
      System.err.println( "close: '" + name_ + "'" );

  // expunge any messages if requested
    if ( expunge && super.mode == READ_WRITE ) {
      expunge();
    }

  // release all resources
    fileCache_.removeAllElements();
    fileCache_ = null;
    dirCache_.removeAllElements();
    dirCache_ = null;
    msgCache_.removeAllElements();
    msgCache_ = null;

    super.mode = -1;  // set to unknown mode
  }

  /**
   * Expunges this folder.
   * This deletes all the messages marked as deleted.
   * <p>
   * Implementation of javax.mail.Folder.expunge().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public Message[]
  expunge() throws MessagingException {
    if ( debug_ )
      System.err.println( "expunge: '" + name_ + "'" );

    checkCacheLoaded();

    int    xsize = fileCache_.size();
    Vector xdeleted = new Vector( xsize, 4 );
    Vector xmsgCache = new Vector( xsize, 4 );
    Vector xfileCache = new Vector( xsize, 4 );

    for ( int i = 0 ; i < xsize ; ++i ) {
      Message xmsg = (Message) msgCache_.elementAt(i);
      if ( xmsg == null )
        continue;

      Flags xflags = xmsg.getFlags();
      if ( xflags.contains( Flags.Flag.DELETED ) ) {
        xdeleted.addElement( xmsg );
      } else {
        xmsgCache.addElement( xmsg );
        xfileCache.addElement( fileCache_.elementAt( i ) );
      }
    }

    for ( int i = 0 ; i < xdeleted.size() ; i++ ) {
      Message xmessage = (Message)xdeleted.elementAt( i );
      File xfile = new File( getMessagePath( xmessage.getMessageNumber() ) );

      if ( xfile.exists() && xfile.isFile() ) {
        xfile.delete();
      }
    }

    fileCache_ = xfileCache;
    msgCache_ = xmsgCache;

  // return the deleted messages as an array
    Message[] xarray = new Message[ xdeleted.size() ];
    xdeleted.copyInto( xarray );
    return xarray;
  }

  /**
   * Indicates whether this folder is open.
   * <p>
   * Implementation of javax.mail.Folder.isOpen().
   */
  public boolean
  isOpen() {
    return ( super.mode == READ_ONLY || super.mode == READ_WRITE );
  }

  /**
   * Returns this folder's Store.
   */
  public Store
  getStore() {
    return super.store;
  }

  /**
   * Returns the permanent flags for this folder.
   * <p>
   * Implementation of javax.mail.Folder.getPermanentFlags().
   */
  public Flags
  getPermanentFlags() {
    return new Flags();
  }
  
  /**
   * Returns the number of messages in this folder.
   * <p>
   * Implementation of javax.mail.Folder.getMessageCount().
   *
   * @exception MessagingException if a messaging error occurred
   */
  public int
  getMessageCount() throws MessagingException {
    if ( ! isOpen() ) return -1;

    return fileCache_.size();
  }

  /**
   * Returns the specified message number from this folder.
   * <p>
   * Implementation of javax.mail.Folder.getMessage().
   */
  public Message
  getMessage( int msgnum ) throws MessagingException {
    if ( debug_ )
      System.err.println( "getMessage: MsgNum = " + msgnum +
                          " cache.length = " + fileCache_.size() );

    checkCacheLoaded();

    MHMessage xmessage = (MHMessage) msgCache_.elementAt( msgnum - 1 );

    if ( xmessage != null ) {
      return xmessage;
    }

    File xfile = new File( getMessagePath( msgnum ) );

    if ( xfile.exists() && xfile.isFile() ) {
      xmessage = new MHMessage( this, msgnum );

      msgCache_.setElementAt( xmessage, msgnum - 1 );
    }

    return xmessage;
  }
  
  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.appendMessages().
   */
  public void
  appendMessages( Message messages[] ) throws MessagingException {
    if ( messages == null || messages.length == 0 )
      return;

    checkCacheLoaded();

    if ( debug_ )
      System.err.println( "appendMessages: messages '" + messages.length + "'" );

    for ( int i = 0; i < messages.length ; ++i ) {
      try {
        if ( messages[i] instanceof MimeMessage ) {
          maxMsgNum_++;

          String xname = "" + maxMsgNum_;

          String xpath = getFullName() + DELIM + xname;

          File xfile = new File( xpath );

          if ( debug_ )
            System.err.println( "APPEND: write '" + xfile.getPath() + "'" );

          FileOutputStream xstream = new FileOutputStream( xfile );
          MimeMessage xmime = (MimeMessage) messages[i];
          xmime.writeTo( xstream );
          xstream.close();

          MHMessage xmessage = new MHMessage( this, msgCache_.size() );

          fileCache_.addElement( xname );
          msgCache_.addElement( xmessage );
        } else {
          throw new MessagingException( "can only process MimeMessages, not '" +
                                        messages[i].getClass().getName() + "'" );
        }
      } catch ( IOException ex ) {
        throw new MessagingException( "while writing message, " +
                                      ex.getMessage() );
      }
    }
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.getParent().
   */
  public Folder
  getParent() throws MessagingException {
    return super.store.getFolder( path_ );
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.list().
   */
  public Folder[]
  list( String s ) throws MessagingException {
    if ( debug_ )
      System.err.println( "list: '" + name_ + "' nameSpace '" + s + "'" );

    Vector xdirectories = new Vector();

    checkCacheLoaded();

    for ( int i = 0 ; i < dirCache_.size() ; i++ ) {
      String xpath = getFullName() + DELIM + (String)dirCache_.elementAt( i );
      File   xdir = new File( xpath );

      if ( xdir.exists() && xdir.isDirectory() ) {
        xdirectories.addElement( xpath );
      }
    }

    MHFolder[] xfolders = new MHFolder[ xdirectories.size() ];

    for ( int i = 0 ; i < xdirectories.size() ; ++i ) {
      String xdir = (String) xdirectories.elementAt(i);
      xfolders[i] = new MHFolder( super.store, xdir, debug_ );
    }
    return xfolders;
  }

  /**
   * 
   */
  private void
  checkCacheLoaded() {
    if ( debug_ )
      System.err.println( "checkCacheLoaded: '" + name_ + "'" );

    if ( fileCache_ == null ) {
      maxMsgNum_ = 0;

      File xdirectory = new File( getFullName() );

      if ( debug_ )
        System.err.println( "CHECKCACHE cache '" + getFullName() + "'" );

      String[] xdirectories = xdirectory.list();
      if ( xdirectories == null )
        xdirectories = new String[0];

      dirCache_ = new Vector( xdirectories.length, 4 );
      fileCache_ = new Vector( xdirectories.length, 4 );
      msgCache_ = new Vector( xdirectories.length, 4 );
      for ( int i = 0 ; i < xdirectories.length ; ++i ) {
      // only add public files and directories on UNIX
        if ( xdirectories[i].startsWith( "." ) ) continue;

        File xfile = new File( xdirectory, xdirectories[i] );
        if ( xfile.exists() && xfile.isFile() ) {
          try {
            int xmsgNum = Integer.parseInt( xdirectories[i] );

            fileCache_.addElement( xdirectories[i] );
            msgCache_.addElement( null );
            if ( xmsgNum > maxMsgNum_ )
              maxMsgNum_ = xmsgNum;
          } catch ( NumberFormatException ex ) {
            // This is not a mail message file, skip it.
          }
        } else if ( xfile.exists() && xfile.isDirectory() ) {
            dirCache_.addElement( xdirectories[i] );
        }
      }

      if ( debug_ ) {
        System.err.println( "CHECKCACHE loaded " + fileCache_.size() +
                            " files, " + dirCache_.size() + " dirs." );
      }
    }
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.getSeparator().
   */
  public char
  getSeparator() {
    return DELIM.charAt( 0 );
  }

  /**
   * The type is ignored.
   * <p>
   * Implementation of javax.mail.Folder.create().
   */
  public boolean
  create( int type ) throws MessagingException {
    if ( debug_ )
      System.err.println( "create: '" + name_ + "' type = " + type );

    String xpath = getFullName();
    File   xdir = new File( xpath );
    return xdir.mkdirs();
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.delete().
   */
  public boolean
  delete( boolean flag ) throws MessagingException {
    if ( debug_ )
      System.err.println( "delete: '" + name_ + "' flag " + flag );

    if ( fileCache_.size() > 0 )
      return false;

    String xpath = getFullName();
    File   xdir = new File( xpath );
    return xdir.delete();
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.renameTo().
   */
  public boolean
  renameTo( Folder folder ) throws MessagingException {
    if ( debug_ )
      System.err.println( "renameTo: '" + name_ + "' folder " + folder );

    String xpath = ((MHStore)super.store).getPath() + DELIM + getFullName();

    String xnewPath = ((MHStore)super.store).getPath() + DELIM + folder.getFullName();

    if ( debug_ )
      System.err.println( "renameTo: old '" + xpath + "' new '" + xnewPath + "'" );

    File xdir = new File( xpath );
    File xnewDir = new File( xnewPath );

    return xdir.renameTo( xnewDir );
  }

  /**
   * aa bb.
   * <p>
   * Implementation of javax.mail.Folder.getFolder().
   */
  public Folder
  getFolder( String s ) throws MessagingException {
    if ( debug_ )
      System.err.println( "getFolder: '" + name_ + "' folder " + s );

  // REVIEW
    return super.store.getFolder( getFullName() + DELIM + s );
  }

}