1 /**
   2  * AUTOHIT 2003
   3  * Copyright Erich P Gatejen (c) 1989,1997,2003,2004
   4  * 
   5  * This program is free software; you can redistribute it and/or modify 
   6  * it under the terms of the GNU General Public License as published by 
   7  * the Free Software Foundation; either version 2 of the License, or (at
   8  * your option) any later version.
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  * 
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Additional license information can be found in the documentation.
  19  * @author Erich P Gatejen
  20  */
  21 package autohit.server.command;
  22 
  23 import java.io.InputStream;
  24 
  25 import org.apache.commons.collections.ExtendedProperties;
  26 
  27 import autohit.common.Constants;
  28 import autohit.server.ServerException;
  29 
  30 /**
  31  * Command registry implementation.  This is immutable.  Once created it is
  32  * set.  If you need to catch changes in the registry, you need to create
  33  * a new instance.  Using the default constructor will cause an exception!
  34  * <p>
  35  * This version of the registry will implement it as a ExtendedProperties
  36  * set.
  37  * <p>
  38  * The registry has two sections.  The first section associates the commands
  39  * with numerics.  There may ne NO duplicate numerics.  (If there are, the system 
  40  * state is undefined.)  This section is constructed as follows:<p>
  41  * <code>
  42  * command.1=compile
  43  * command.2=dump
  44  * <br>
  45  * ("command.")(numeric)("=")(string name)</code><p>
  46  * The second section contains entries for the commands defined in section one.
  47  * This section is as follows:<p>
  48  * <code>
  49  * compile.class=autohit.server.command.CommandCompile
  50  * compile.help=This will compile a script found at the target.
  51  * <br>
  52  * (string name)(".class=")(class name for implementation)
  53  * (string name)(".help=")(string giving a hint about the command)</code><p>
  54  * 
  55  * @author Erich P. Gatejen
  56  * @version 1.0
  57  * <i>Version History</i>
  58  * <code>EPG - Initial - 25Jul03</code>
  59  * 
  60  */
  61 public class CommandRegistry extends ExtendedProperties {
  62 
  63 	final static long serialVersionUID = 1;
  64 	
  65 	/**
  66 	 * field literals
  67 	 */
  68 	public final static String FL_COMMAND = "command.";
  69 	public final static String FL_CLASS = ".class";
  70 	public final static String FL_HELP = ".help";
  71 
  72 	/**
  73 	 * Default Constructor.  Don't use!
  74 	 * @throws ServerException
  75 	 */
  76 	public CommandRegistry() throws ServerException {
  77 		throw new ServerException(
  78 			"Programmer used default constructor for CommandRegsitry.  this is a bug.",
  79 			ServerException.CODE_SW_DETECTED_FAULT);
  80 	}
  81 
  82 	/**
  83 	 * Constructor to create and load from an input stream.
  84 	 * @param is input stream from where to read the registry
  85 	 * @throws ServerException
  86 	 */
  87 	public CommandRegistry(InputStream is) throws ServerException {
  88 		super();
  89 		try {
  90 			load(is);
  91 		} catch (Exception e) {
  92 			throw new ServerException(
  93 				"Failed to load the command registry.  message="
  94 					+ e.getMessage(),
  95 				ServerException.CODE_COMMAND_REGISTRY_FAULT);
  96 		}
  97 	}
  98 
  99 	/**
 100 	 * Get an instance of the command specified by the numeric
 101 	 * @param numeric numeric for the command
 102 	 * @throws ServerException
 103 	 * @return the object instance.
 104 	 */
 105 	public Object instance(int numeric) throws ServerException {
 106 
 107 		String name = Constants.UNKNOWN;
 108 		Command target = null;
 109 		String classname = Constants.UNKNOWN;
 110 
 111 		try {
 112 			// See if the atom points to a valid command
 113 			String numericS = FL_COMMAND + Integer.toString(numeric);
 114 			if (this.containsKey(numericS)) {
 115 
 116 				// Find the name
 117 				name = this.getString(numericS);
 118 				classname = this.getString(name + FL_CLASS);
 119 
 120 				// create the instance
 121 				Class t = Class.forName(classname);
 122 				target = (Command) t.newInstance();
 123 
 124 			} else {
 125 				throw new ServerException(
 126 					"Command Registry does not have requested command.  Command ignored.  Command numeric="
 127 						+ numeric,
 128 					ServerException.CODE_COMMAND_UNKNOWN);
 129 			}
 130 			
 131 		} catch (ClassCastException cee) {
 132 			throw new ServerException(
 133 				"Command Registry instance() failed because of malformed '.class' entry for "
 134 					+ name + ".  numeric="	+ numeric,
 135 				ServerException.CODE_COMMAND_REGISTRY_FAULT, cee);
 136 		} catch (ClassNotFoundException cne) {
 137 			throw new ServerException(
 138 				"Command Registry instance() failed because of malformed '.class' entry for "
 139 					+ name
 140 					+ ".  ClassNotFound for entry=["
 141 					+ classname
 142 					+ "].",
 143 				ServerException.CODE_COMMAND_REGISTRY_FAULT,
 144 				cne);
 145 		} catch (ServerException se) {
 146 			throw se;
 147 		} catch (Exception ee) {
 148 			throw new ServerException(
 149 				"Command Registry instance() failed to gross exception.  message="
 150 					+ ee.getMessage(),
 151 				ServerException.CODE_COMMAND_REGISTRY_FAULT,
 152 				ee);
 153 		}
 154 		return target;
 155 	}
 156 }