001 // Copyright 2004, 2005 The Apache Software Foundation
002 //
003 // Licensed under the Apache License, Version 2.0 (the "License");
004 // you may not use this file except in compliance with the License.
005 // You may obtain a copy of the License at
006 //
007 // http://www.apache.org/licenses/LICENSE-2.0
008 //
009 // Unless required by applicable law or agreed to in writing, software
010 // distributed under the License is distributed on an "AS IS" BASIS,
011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012 // See the License for the specific language governing permissions and
013 // limitations under the License.
014
015 package org.apache.hivemind;
016
017 import java.util.Collection;
018
019 /**
020 * Static utility class for HiveMind.
021 *
022 * @author Howard Lewis Ship
023 */
024 public final class HiveMind
025 {
026 /**
027 * The full id of the {@link org.apache.hivemind.service.ThreadEventNotifier} service.
028 */
029 public static final String THREAD_EVENT_NOTIFIER_SERVICE = "hivemind.ThreadEventNotifier";
030
031 /**
032 * The full id of the {@link org.apache.hivemind.service.ThreadLocale} service.
033 *
034 * @since 1.1
035 */
036
037 public static final String THREAD_LOCALE_SERVICE = "hivemind.ThreadLocale";
038
039 /**
040 * The full id of the {@link org.apache.hivemind.service.InterfaceSynthesizer} service.
041 *
042 * @since 1.1
043 */
044
045 public static final String INTERFACE_SYNTHESIZER_SERVICE = "hivemind.InterfaceSynthesizer";
046
047 /**
048 * An object used to synchronize access to {@link java.beans.Introspector} (which is not fully
049 * threadsafe).
050 *
051 * @since 1.1
052 */
053
054 public static final Object INTROSPECTOR_MUTEX = new Object();
055
056 private HiveMind()
057 {
058 // Prevent instantiation
059 }
060
061 public static ApplicationRuntimeException createRegistryShutdownException()
062 {
063 return new ApplicationRuntimeException(HiveMindMessages.registryShutdown());
064 }
065
066 /**
067 * Selects the first {@link Location} in an array of objects. Skips over nulls. The objects may
068 * be instances of Location or {@link Locatable}. May return null if no Location can be found.
069 */
070
071 public static Location findLocation(Object[] locations)
072 {
073 for (int i = 0; i < locations.length; i++)
074 {
075 Object location = locations[i];
076
077 Location result = getLocation(location);
078
079 if (result != null)
080 return result;
081
082 }
083
084 return null;
085 }
086
087 /**
088 * Extracts a location from an object, checking to see if it implement {@link Location} or
089 * {@link Locatable}.
090 *
091 * @return the Location, or null if it can't be found
092 */
093 public static Location getLocation(Object object)
094 {
095 if (object == null)
096 return null;
097
098 if (object instanceof Location)
099 return (Location) object;
100
101 if (object instanceof Locatable)
102 {
103 Locatable locatable = (Locatable) object;
104
105 return locatable.getLocation();
106 }
107
108 return null;
109 }
110
111 /**
112 * Invokes {@link #getLocation(Object)}, then translate the result to a string value, or
113 * "unknown location" if null.
114 */
115 public static String getLocationString(Object object)
116 {
117 Location l = getLocation(object);
118
119 if (l != null)
120 return l.toString();
121
122 return HiveMindMessages.unknownLocation();
123 }
124
125 /**
126 * Returns true if the string is null, empty, or contains only whitespace.
127 * <p>
128 * The commons-lang library provides a version of this, but the naming and behavior changed
129 * between 1.0 and 2.0, which causes some dependency issues.
130 */
131 public static boolean isBlank(String string)
132 {
133 if (string == null || string.length() == 0)
134 return true;
135
136 if (string.trim().length() == 0)
137 return true;
138
139 return false;
140 }
141
142 /**
143 * As with {@link #isBlank(String)}, but inverts the response.
144 */
145 public static boolean isNonBlank(String string)
146 {
147 return !isBlank(string);
148 }
149
150 /**
151 * Updates the location of an object, if the object implements {@link LocationHolder}.
152 *
153 * @param holder
154 * the object to be updated
155 * @param location
156 * the location to assign to the holder object
157 */
158 public static void setLocation(Object holder, Location location)
159 {
160 if (holder != null && holder instanceof LocationHolder)
161 {
162 LocationHolder lh = (LocationHolder) holder;
163
164 lh.setLocation(location);
165 }
166 }
167
168 /**
169 * Returns true if the Collection is null or empty.
170 */
171 public static boolean isEmpty(Collection c)
172 {
173 return c == null || c.isEmpty();
174 }
175 }