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 import org.apache.hivemind.impl.LocationImpl;
020 import org.apache.hivemind.util.ClasspathResource;
021
022 /**
023 * Static utility class for HiveMind.
024 *
025 * @author Howard Lewis Ship
026 */
027 public final class HiveMind
028 {
029 /**
030 * The full id of the {@link org.apache.hivemind.service.ThreadEventNotifier} service.
031 */
032 public static final String THREAD_EVENT_NOTIFIER_SERVICE = "hivemind.ThreadEventNotifier";
033
034 /**
035 * The full id of the {@link org.apache.hivemind.service.ThreadLocale} service.
036 *
037 * @since 1.1
038 */
039
040 public static final String THREAD_LOCALE_SERVICE = "hivemind.ThreadLocale";
041
042 /**
043 * The full id of the {@link org.apache.hivemind.service.InterfaceSynthesizer} service.
044 *
045 * @since 1.1
046 */
047
048 public static final String INTERFACE_SYNTHESIZER_SERVICE = "hivemind.InterfaceSynthesizer";
049
050 /**
051 * The full id of the {@link org.apache.hivemind.service.Autowiring} service.
052 *
053 * @since 2.0
054 */
055
056 public static final String AUTOWIRING_SERVICE = "hivemind.Autowiring";
057
058 /**
059 * An object used to synchronize access to {@link java.beans.Introspector} (which is not fully
060 * threadsafe).
061 *
062 * @since 1.1
063 */
064
065 public static final Object INTROSPECTOR_MUTEX = new Object();
066
067 private HiveMind()
068 {
069 // Prevent instantiation
070 }
071
072 public static ApplicationRuntimeException createRegistryShutdownException()
073 {
074 return new ApplicationRuntimeException(HiveMindMessages.registryShutdown());
075 }
076
077 /**
078 * Selects the first {@link Location} in an array of objects. Skips over nulls. The objects may
079 * be instances of Location or {@link Locatable}. May return null if no Location can be found.
080 */
081
082 public static Location findLocation(Object[] locations)
083 {
084 for (int i = 0; i < locations.length; i++)
085 {
086 Object location = locations[i];
087
088 Location result = getLocation(location);
089
090 if (result != null)
091 return result;
092
093 }
094
095 return null;
096 }
097
098 /**
099 * Extracts a location from an object, checking to see if it implement {@link Location} or
100 * {@link Locatable}.
101 *
102 * @return the Location, or null if it can't be found
103 */
104 public static Location getLocation(Object object)
105 {
106 if (object == null)
107 return null;
108
109 if (object instanceof Location)
110 return (Location) object;
111
112 if (object instanceof Locatable)
113 {
114 Locatable locatable = (Locatable) object;
115
116 return locatable.getLocation();
117 }
118
119 return null;
120 }
121
122 /**
123 * Invokes {@link #getLocation(Object)}, then translate the result to a string value, or
124 * "unknown location" if null.
125 */
126 public static String getLocationString(Object object)
127 {
128 Location l = getLocation(object);
129
130 if (l != null)
131 return l.toString();
132
133 return HiveMindMessages.unknownLocation();
134 }
135
136 public static Location getClassLocation(Class theClass, ClassResolver classResolver)
137 {
138 String path = "/" + theClass.getName().replace('.', '/');
139
140 Resource r = new ClasspathResource(classResolver, path);
141
142 return new LocationImpl(r);
143 }
144
145 /**
146 * Returns true if the string is null, empty, or contains only whitespace.
147 * <p>
148 * The commons-lang library provides a version of this, but the naming and behavior changed
149 * between 1.0 and 2.0, which causes some dependency issues.
150 */
151 public static boolean isBlank(String string)
152 {
153 if (string == null || string.length() == 0)
154 return true;
155
156 if (string.trim().length() == 0)
157 return true;
158
159 return false;
160 }
161
162 /**
163 * As with {@link #isBlank(String)}, but inverts the response.
164 */
165 public static boolean isNonBlank(String string)
166 {
167 return !isBlank(string);
168 }
169
170 /**
171 * Updates the location of an object, if the object implements {@link LocationHolder}.
172 *
173 * @param holder
174 * the object to be updated
175 * @param location
176 * the location to assign to the holder object
177 */
178 public static void setLocation(Object holder, Location location)
179 {
180 if (holder != null && holder instanceof LocationHolder)
181 {
182 LocationHolder lh = (LocationHolder) holder;
183
184 lh.setLocation(location);
185 }
186 }
187
188 /**
189 * Returns true if the Collection is null or empty.
190 */
191 public static boolean isEmpty(Collection c)
192 {
193 return c == null || c.isEmpty();
194 }
195 }