001 /*
002 * Copyright 2005 Stephen J. McConnell.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
013 * implied.
014 *
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package net.dpml.metro.data;
020
021 import java.io.Serializable;
022 import java.net.URI;
023 import java.net.URISyntaxException;
024
025 /**
026 * Abstract base class for directives.
027 *
028 * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
029 * @version 1.0.4
030 */
031 public abstract class AbstractDirective implements Serializable
032 {
033 //--------------------------------------------------------------------------
034 // static
035 //--------------------------------------------------------------------------
036
037 /**
038 * Serial version identifier.
039 */
040 static final long serialVersionUID = 1L;
041
042 //--------------------------------------------------------------------------
043 // utilities
044 //--------------------------------------------------------------------------
045
046 /**
047 * Return the hashcode for the instance.
048 * @return the instance hashcode
049 */
050 public int hashCode()
051 {
052 return getClass().hashCode();
053 }
054
055 /**
056 * Utility to hash an array.
057 * @param array the array
058 * @return the hash value
059 */
060 int hashArray( Object[] array )
061 {
062 if( null == array )
063 {
064 return 0;
065 }
066 int hash = 0;
067 for( int i=0; i<array.length; i++ )
068 {
069 Object object = array[i];
070 hash ^= hashValue( object );
071 }
072 return hash;
073 }
074
075 /**
076 * Utility to hash an object.
077 * @param value the object
078 * @return the hash value
079 */
080 int hashValue( Object value )
081 {
082 if( null == value )
083 {
084 return 0;
085 }
086 else if( value instanceof Object[] )
087 {
088 return hashArray( (Object[]) value );
089 }
090 else
091 {
092 return value.hashCode();
093 }
094 }
095
096 /**
097 * Test if the supplied object is equal to this object.
098 * @param other the object to compare with this instance
099 * @return TRUE if the supplied object is equal to this object
100 */
101 public boolean equals( Object other )
102 {
103 if( null == other )
104 {
105 return false;
106 }
107 else
108 {
109 return ( other instanceof AbstractDirective );
110 }
111 }
112
113 /**
114 * Utility to compare two object for equality.
115 * @param a the first object
116 * @param b the second object
117 * @return true if the objects are equal
118 */
119 boolean equals( Object a, Object b )
120 {
121 if( null == a )
122 {
123 return ( null == b );
124 }
125 else
126 {
127 return a.equals( b );
128 }
129 }
130
131 //--------------------------------------------------------------------------
132 // Part
133 //--------------------------------------------------------------------------
134
135 /**
136 * Return the part handler uri.
137 * @return the uri of the part handler
138 */
139 public URI getPartHandlerURI()
140 {
141 return PART_HANDLER_URI;
142 }
143
144 /**
145 * Static utility to create the part handler uri.
146 * @param spec the part handler uri string
147 * @return the constant part handler uri
148 */
149 protected static URI setupURI( String spec )
150 {
151 try
152 {
153 return new URI( spec );
154 }
155 catch( URISyntaxException ioe )
156 {
157 return null;
158 }
159 }
160
161 private static final URI PART_HANDLER_URI = setupURI( "artifact:part:dpml/metro/dpml-metro-runtime#1.0.4" );
162
163 }