1 /*
2 * Copyright 1999-2001,2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.apache.commons.workflow.base;
18
19
20 import java.util.HashMap;
21 import org.apache.commons.workflow.Activity;
22 import org.apache.commons.workflow.Registry;
23
24
25 /**
26 * <p><strong>BaseRegistry</strong> is a convenient base class for more
27 * sophisticated <code>Registry</code> implementations.</p>
28 *
29 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
30 * @author Craig R. McClanahan
31 */
32
33 public class BaseRegistry implements Registry {
34
35
36 // ----------------------------------------------------- Instance Variables
37
38
39 /**
40 * The set of Activity instances registered with this Registry, keyed
41 * by identifier.
42 */
43 protected HashMap activities = new HashMap();
44
45
46 // ------------------------------------------------------------- Properties
47
48
49 // --------------------------------------------------------- Public Methods
50
51
52 /**
53 * Add a new Activity to the set of Activity instances known to this
54 * Registry.
55 *
56 * @param activity The new activity to be added
57 */
58 public void addActivity(Activity activity) {
59
60 activities.put(activity.getId(), activity);
61
62 }
63
64
65 /**
66 * Clear any existing Activity instances registered with this Registry.
67 */
68 public void clear() {
69
70 activities.clear();
71
72 }
73
74
75 /**
76 * Return the complete set of Activity instances associated with
77 * this Activity. If there are no such registered Activity instances,
78 * a zero-length array is returned.
79 */
80 public Activity[] findActivities() {
81
82 Activity results[] = new Activity[activities.size()];
83 return ((Activity[]) activities.values().toArray(results));
84
85 }
86
87
88 /**
89 * Return the registered Activity with the specified identifier, if any;
90 * otherwise return <code>null</code>.
91 *
92 * @param id Identifier of the desired Activity
93 */
94 public Activity findActivity(String id) {
95
96 return ((Activity) activities.get(id));
97
98 }
99
100
101 /**
102 * Remove the specified Activity from this Registry.
103 *
104 * @param activity The Activity to be removed
105 */
106 public void removeActivity(Activity activity) {
107
108 activities.remove(activity.getId());
109
110 }
111
112
113 // ------------------------------------------------------- Static Variables
114
115
116 /**
117 * The singleton registry instance.
118 */
119 protected static Registry registry = null;
120
121
122 // --------------------------------------------------------- Static Methods
123
124
125 /**
126 * Factory method to return a Singleton (per class loader)
127 * <code>Registry</code> instance.
128 */
129 public static Registry getRegistry() {
130
131 if (registry == null)
132 registry = new BaseRegistry();
133 return (registry);
134
135 }
136
137
138 }