editorviewer.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: EditorViewer.java,v 1.3 2001/05/07 12:37:21 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.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;

import javax.mail.internet.ContentType;
import javax.mail.internet.ParseException;
import javax.mail.internet.MimeUtility;

import javax.activation.DataHandler;
import javax.activation.CommandObject;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;

import java.util.Enumeration;

import javax.swing.JPanel;

import javax.swing.JTextPane;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;
import javax.swing.text.Document;
import javax.swing.text.StyledDocument;
import javax.swing.text.DefaultStyledDocument;
import javax.swing.text.Style;
import javax.swing.text.EditorKit;
import javax.swing.text.BadLocationException;


/**
 * Class EditorViewer implements a CommandObject for the Java Activation Framework.
 * The only verb supported is "view", loading the contents of the data into
 * an EditorPane for display. And as you've already guessed, allows the data to
 * be viewed by activating the pane.
 */
public class EditorViewer
  extends JPanel
  implements CommandObject
{
  JScrollPane   scroller = null;
  JEditorPane   editorPane = null;


  /**
   * Construct an empty viewer, which can be loaded later.
   */
  public
  EditorViewer() {
    this( null, null );
  }

  /**
   * Construct a viewer for the given content and type.
   * <p>
   * @param content data contents, possibly character encoded
   * @param contentType MIME formatted Content-Type header string
   */
  public
  EditorViewer( InputStream content, String contentType ) {
    this.setDoubleBuffered( true );
    this.setBackground( Color.white );

    this.setLayout( new BorderLayout() );

    this.scroller = new JScrollPane();
    this.scroller.setPreferredSize( new Dimension( 480, 320 ) );

    this.add( this.scroller );

    // now display our message
    if ( content != null && contentType != null ) {
      this.setMessage( content, contentType );
    }
  }

  /**
   * Sets the contents of the viewer from the given content and type.
   * <p>
   * There are two distinct ways to read the data, from a text reader
   * for documents of type text/plain, and directly from a stream for
   * others. (Don't ask me why! I belive it to be another GOTCHA from SUN
   * because the Editor Kits should determin wether to make a text reader
   * based on the content type set! OH HUM...)
   * <p>
   * One other point is that the contentType passed is MIME formatted and
   * can contain a charset parameter which is set to a MIME value. The charset
   * needs to be converted to a JAVA value before the EditorPane can use it.
   * <p>
   * @param content data contents, possibly character encoded
   * @param contentType MIME formatted Content-Type header string
   */
  public void
  setMessage( InputStream content, String contentType ) {
  // remove any other components
    this.scroller.getViewport().removeAll();

  // check the content type and convert to JAVA charset
    ContentType xct = new ContentType();
    try {
      xct = new ContentType( contentType );
    } catch ( ParseException ex ) {
    // assume text/plain
      xct.setPrimaryType( "text" );
      xct.setSubType( "plain" );
    }
    String xjcharset = "ISO-8859-1"; // US-ASCII in MIME terms
    if ( xct.getParameter( "charset" ) != null ) {
      xjcharset = MimeUtility.javaCharset( xct.getParameter( "charset" ) );
    }
    xct.setParameter( "charset", xjcharset );

  // determine the editor based on content type
    this.editorPane = new JEditorPane();
    this.editorPane.setEditable( false );
    this.editorPane.setContentType( xct.toString().toLowerCase() );

  // set the contents of the editor
    try {
      EditorKit xeditor = this.editorPane.getEditorKit();
      Document xdoc = xeditor.createDefaultDocument();
      if ( xct.match( "text/plain" ) ) {
        BufferedReader xreader =
          new BufferedReader( new InputStreamReader( content, xjcharset ) );
        xeditor.read( xreader, xdoc, 0 );
      } else {
        xeditor.read( content, xdoc, 0 );
      }
      this.editorPane.setDocument( xdoc );
    } catch ( IOException ex ) {
      ex.printStackTrace( System.err );
    } catch ( BadLocationException ex ) {
      ex.printStackTrace( System.err );
    }

    this.scroller.getViewport().add( this.editorPane );

    this.invalidate();
    this.validate();
  }

  /**
   * 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 {
    String contentType = dh.getContentType();
    InputStream content = dh.getInputStream();

    this.setMessage( content, contentType );

    content.close();
  }

}