libjava/classpath/javax/activation/CommandMap.java

/* CommandMap.java -- Registry of available command objects.
   Copyright (C) 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */

package javax.activation;

/**
 * Registry of command objects available to the system.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 * @version 1.1
 */
public abstract class CommandMap
{

  /* Class scope */

  private static CommandMap defaultCommandMap;

  /**
   * Returns the default command map.
   * This returns a MailcapCommandMap if no value has been set using
   * <code>setDefaultCommandMap</code>.
   */
  public static CommandMap getDefaultCommandMap()
  {
    if (defaultCommandMap == null)
      {
        defaultCommandMap = new MailcapCommandMap();
      }
    return defaultCommandMap;
  }

  /**
   * Sets the default command map.
   * @param commandMap the new default command map
   */
  public static void setDefaultCommandMap(CommandMap commandMap)
  {
    SecurityManager security = System.getSecurityManager();
    if (security != null)
      {
        try
          {
            security.checkSetFactory();
          }
        catch (SecurityException e)
          {
            if (commandMap != null && CommandMap.class.getClassLoader() !=
                commandMap.getClass().getClassLoader())
              {
                throw e;
              }
          }
      }
    defaultCommandMap = commandMap;
  }

  /* Instance scope */

  /**
   * Returns the list of preferred commands for a MIME type.
   * @param mimeType the MIME type
   */
  public abstract CommandInfo[] getPreferredCommands(String mimeType);

  /**
   * Returns the complete list of commands for a MIME type.
   * @param mimeType the MIME type
   */
  public abstract CommandInfo[] getAllCommands(String mimeType);

  /**
   * Returns the command corresponding to the specified MIME type and
   * command name.
   * @param mimeType the MIME type
   * @param cmdName the command name
   */
  public abstract CommandInfo getCommand(String mimeType, String cmdName);

  /**
   * Returns a DataContentHandler corresponding to the MIME type.
   * @param mimeType the MIME type
   */
  public abstract DataContentHandler createDataContentHandler(String mimeType);

  /**
   * Get all the MIME types known to this command map.
   * If the command map doesn't support this operation, null is returned.
   * @return array of MIME types as strings, or null if not supported
   * @since JAF 1.1
   */
  public String[] getMimeTypes()
  {
    return null;
  }

  /**
   * Get the preferred command list from a MIME Type. The actual semantics
   * are determined by the implementation of the CommandMap.
   * <p>
   * The <code>DataSource</code> provides extra information, such as
   * the file name, that a CommandMap implementation may use to further
   * refine the list of commands that are returned.  The implementation
   * in this class simply calls the <code>getPreferredCommands</code>
   * method that ignores this argument.
   * @param mimeType the MIME type
   * @param ds a DataSource for the data
   * @return the CommandInfo classes that represent the command Beans.
   * @since JAF 1.1
   */
  public CommandInfo[] getPreferredCommands(String mimeType,
                                            DataSource ds)
  {
    return getPreferredCommands(mimeType);
  }

  /**
   * Get all the available commands for this type. This method
   * should return all the possible commands for this MIME type.
   * <p>
   * The <code>DataSource</code> provides extra information, such as
   * the file name, that a CommandMap implementation may use to further
   * refine the list of commands that are returned.  The implementation
   * in this class simply calls the <code>getAllCommands</code>
   * method that ignores this argument.
   * @param mimeType the MIME type
   * @param ds a DataSource for the data
   * @return the CommandInfo objects representing all the commands.
   * @since JAF 1.1
   */
  public CommandInfo[] getAllCommands(String mimeType, DataSource ds)
  {
    return getAllCommands(mimeType);
  }

  /**
   * Get the default command corresponding to the MIME type.
   * <p>
   * The <code>DataSource</code> provides extra information, such as
   * the file name, that a CommandMap implementation may use to further
   * refine the command that is chosen.  The implementation
   * in this class simply calls the <code>getCommand</code>
   * method that ignores this argument.
   * @param mimeType the MIME type
   * @param cmdName the command name
   * @param ds a DataSource for the data
   * @return the CommandInfo corresponding to the command.
   * @since JAF 1.1
   */
  public CommandInfo getCommand(String mimeType, String cmdName,
                                DataSource ds)
  {
    return getCommand(mimeType, cmdName);
  }

  /**
   * Locate a DataContentHandler that corresponds to the MIME type.
   * The mechanism and semantics for determining this are determined
   * by the implementation of the particular CommandMap.
   * <p>
   * The <code>DataSource</code> provides extra information, such as
   * the file name, that a CommandMap implementation may use to further
   * refine the choice of DataContentHandler.  The implementation
   * in this class simply calls the <code>createDataContentHandler</code>
   * method that ignores this argument.
   * @param mimeType the MIME type
   * @param ds a DataSource for the data
   * @return the DataContentHandler for the MIME type
   * @since JAF 1.1
   */
  public DataContentHandler createDataContentHandler(String mimeType,
                                                     DataSource ds)
  {
    return createDataContentHandler(mimeType);
  }

}