001    /* CommandMap.java -- Registry of available command objects.
002       Copyright (C) 2004, 2005 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package javax.activation;
039    
040    /**
041     * Registry of command objects available to the system.
042     * 
043     * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
044     * @version 1.1
045     */
046    public abstract class CommandMap
047    {
048    
049      /* Class scope */
050      
051      private static CommandMap defaultCommandMap;
052      
053      /**
054       * Returns the default command map.
055       * This returns a MailcapCommandMap if no value has been set using
056       * <code>setDefaultCommandMap</code>.
057       */
058      public static CommandMap getDefaultCommandMap()
059      {
060        if (defaultCommandMap == null)
061          {
062            defaultCommandMap = new MailcapCommandMap();
063          }
064        return defaultCommandMap;
065      }
066      
067      /**
068       * Sets the default command map.
069       * @param commandMap the new default command map
070       */
071      public static void setDefaultCommandMap(CommandMap commandMap)
072      {
073        SecurityManager security = System.getSecurityManager();
074        if (security != null)
075          {
076            try
077              {
078                security.checkSetFactory();
079              }
080            catch (SecurityException e)
081              {
082                if (commandMap != null && CommandMap.class.getClassLoader() !=
083                    commandMap.getClass().getClassLoader())
084                  {
085                    throw e;
086                  }
087              }
088          }
089        defaultCommandMap = commandMap;
090      }
091    
092      /* Instance scope */
093      
094      /**
095       * Returns the list of preferred commands for a MIME type.
096       * @param mimeType the MIME type
097       */
098      public abstract CommandInfo[] getPreferredCommands(String mimeType);
099      
100      /**
101       * Returns the complete list of commands for a MIME type.
102       * @param mimeType the MIME type
103       */
104      public abstract CommandInfo[] getAllCommands(String mimeType);
105      
106      /**
107       * Returns the command corresponding to the specified MIME type and
108       * command name.
109       * @param mimeType the MIME type
110       * @param cmdName the command name
111       */
112      public abstract CommandInfo getCommand(String mimeType, String cmdName);
113      
114      /**
115       * Returns a DataContentHandler corresponding to the MIME type.
116       * @param mimeType the MIME type
117       */
118      public abstract DataContentHandler createDataContentHandler(String mimeType);
119      
120      /**
121       * Get all the MIME types known to this command map.
122       * If the command map doesn't support this operation, null is returned.
123       * @return array of MIME types as strings, or null if not supported
124       * @since JAF 1.1
125       */
126      public String[] getMimeTypes()
127      {
128        return null;
129      }
130      
131      /**
132       * Get the preferred command list from a MIME Type. The actual semantics
133       * are determined by the implementation of the CommandMap.
134       * <p>
135       * The <code>DataSource</code> provides extra information, such as
136       * the file name, that a CommandMap implementation may use to further
137       * refine the list of commands that are returned.  The implementation
138       * in this class simply calls the <code>getPreferredCommands</code>
139       * method that ignores this argument.
140       * @param mimeType the MIME type
141       * @param ds a DataSource for the data
142       * @return the CommandInfo classes that represent the command Beans.
143       * @since JAF 1.1
144       */
145      public CommandInfo[] getPreferredCommands(String mimeType,
146                                                DataSource ds)
147      {
148        return getPreferredCommands(mimeType);
149      }
150      
151      /**
152       * Get all the available commands for this type. This method
153       * should return all the possible commands for this MIME type.
154       * <p>
155       * The <code>DataSource</code> provides extra information, such as
156       * the file name, that a CommandMap implementation may use to further
157       * refine the list of commands that are returned.  The implementation
158       * in this class simply calls the <code>getAllCommands</code>
159       * method that ignores this argument.
160       * @param mimeType the MIME type
161       * @param ds a DataSource for the data
162       * @return the CommandInfo objects representing all the commands.
163       * @since JAF 1.1
164       */
165      public CommandInfo[] getAllCommands(String mimeType, DataSource ds)
166      {
167        return getAllCommands(mimeType);
168      }
169      
170      /**
171       * Get the default command corresponding to the MIME type.
172       * <p>
173       * The <code>DataSource</code> provides extra information, such as
174       * the file name, that a CommandMap implementation may use to further
175       * refine the command that is chosen.  The implementation
176       * in this class simply calls the <code>getCommand</code>
177       * method that ignores this argument.
178       * @param mimeType the MIME type
179       * @param cmdName the command name
180       * @param ds a DataSource for the data
181       * @return the CommandInfo corresponding to the command.
182       * @since JAF 1.1
183       */
184      public CommandInfo getCommand(String mimeType, String cmdName,
185                                    DataSource ds)
186      {
187        return getCommand(mimeType, cmdName);
188      }
189      
190      /**
191       * Locate a DataContentHandler that corresponds to the MIME type.
192       * The mechanism and semantics for determining this are determined
193       * by the implementation of the particular CommandMap.
194       * <p>
195       * The <code>DataSource</code> provides extra information, such as
196       * the file name, that a CommandMap implementation may use to further
197       * refine the choice of DataContentHandler.  The implementation
198       * in this class simply calls the <code>createDataContentHandler</code>
199       * method that ignores this argument.
200       * @param mimeType the MIME type
201       * @param ds a DataSource for the data
202       * @return the DataContentHandler for the MIME type
203       * @since JAF 1.1
204       */
205      public DataContentHandler createDataContentHandler(String mimeType,
206                                                         DataSource ds)
207      {
208        return createDataContentHandler(mimeType);
209      }  
210    
211    }
212