smimemanager.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: SMIMEManager.java,v 1.3 2001/05/07 12:35:28 kunugi Exp $
**
** Copyright (c) 2000-2001 Jeff Gay
** on behalf of ICEMail.org <http://www.icemail.org>
** 
** 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.smime;

import org.icemail.Package;

/**
 * SMIME Library Manager
 */
public class SMIMEManager
{
  private static final int Debug_ = Package.DEBUG ? Package.getLevel( "SMIMEManager" ) : 0;

  /**
   * Get a SMIME library, instantiating the library by class name.
   * Objects can only be instantiated if there is a constructor without parameters.
   *
   * @param classname the name of the class to instantiate
   * @return an instantiatation of the class, i.e. SMIMELibrary
   */
  public static SMIMELibrary
  getSMIMELibrary( String classname )
    throws ClassNotFoundException, InstantiationException, IllegalAccessException {
    try {
      Class xclass = Class.forName( classname );
      return (SMIMELibrary)xclass.newInstance();
    } catch ( NoClassDefFoundError xex ) {
      throw new ClassNotFoundException( xex.toString() );
    }
  }
}