001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.chain.impl;
018
019
020 import java.util.HashMap;
021 import java.util.Collections;
022 import java.util.Iterator;
023 import java.util.Map;
024 import org.apache.commons.chain.Catalog;
025 import org.apache.commons.chain.Command;
026
027
028 /**
029 * <p>Simple in-memory implementation of {@link Catalog}. This class can
030 * also be used as the basis for more advanced implementations.</p>
031 *
032 * <p>This implementation is thread-safe.</p>
033 *
034 * @author Craig R. McClanahan
035 * @author Matthew J. Sgarlata
036 * @version $Revision: 480477 $ $Date: 2006-11-29 08:34:52 +0000 (Wed, 29 Nov 2006) $
037 */
038
039 public class CatalogBase implements Catalog {
040
041
042 // ----------------------------------------------------- Instance Variables
043
044
045 /**
046 * <p>The map of named {@link Command}s, keyed by name.
047 */
048 protected Map commands = Collections.synchronizedMap(new HashMap());
049
050
051 // --------------------------------------------------------- Constructors
052
053 /**
054 * Create an empty catalog.
055 */
056 public CatalogBase() { }
057
058 /**
059 * <p>Create a catalog whose commands are those specified in the given <code>Map</code>.
060 * All Map keys should be <code>String</code> and all values should be <code>Command</code>.</p>
061 *
062 * @param commands Map of Commands.
063 *
064 * @since Chain 1.1
065 */
066 public CatalogBase( Map commands ) {
067 this.commands = Collections.synchronizedMap(commands);
068 }
069
070 // --------------------------------------------------------- Public Methods
071
072
073 /**
074 * <p>Add a new name and associated {@link Command}
075 * to the set of named commands known to this {@link Catalog},
076 * replacing any previous command for that name.
077 *
078 * @param name Name of the new command
079 * @param command {@link Command} to be returned
080 * for later lookups on this name
081 */
082 public void addCommand(String name, Command command) {
083
084 commands.put(name, command);
085
086 }
087
088 /**
089 * <p>Return the {@link Command} associated with the
090 * specified name, if any; otherwise, return <code>null</code>.</p>
091 *
092 * @param name Name for which a {@link Command}
093 * should be retrieved
094 * @return The Command associated with the specified name.
095 */
096 public Command getCommand(String name) {
097
098 return ((Command) commands.get(name));
099
100 }
101
102
103 /**
104 * <p>Return an <code>Iterator</code> over the set of named commands
105 * known to this {@link Catalog}. If there are no known commands,
106 * an empty Iterator is returned.</p>
107 * @return An iterator of the names in this Catalog.
108 */
109 public Iterator getNames() {
110
111 return (commands.keySet().iterator());
112
113 }
114
115 /**
116 * Converts this Catalog to a String. Useful for debugging purposes.
117 * @return a representation of this catalog as a String
118 */
119 public String toString() {
120
121 Iterator names = getNames();
122 StringBuffer str =
123 new StringBuffer("[" + this.getClass().getName() + ": ");
124
125 while (names.hasNext()) {
126 str.append(names.next());
127 if (names.hasNext()) {
128 str.append(", ");
129 }
130 }
131 str.append("]");
132
133 return str.toString();
134
135 }
136 }