001    package org.apache.ojb.broker.metadata;
002    
003    /* Copyright 2002-2005 The Apache Software Foundation
004     *
005     * Licensed under the Apache License, Version 2.0 (the "License");
006     * you may not use this file except in compliance with the License.
007     * 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    
018    import java.io.Serializable;
019    import java.util.*;
020    
021    /**
022     * base class for all Descriptors. It is used to implement the AttributeContainer
023     * interface which provides mechanics for user defined attributes.
024     * @author Thomas Mahler
025     */
026    class DescriptorBase implements AttributeContainer, Serializable
027    {
028            static final long serialVersionUID = 713914612744155925L;
029        /** holds user defined attributes */
030        private Map attributeMap = null;
031    
032        /**
033         * Constructor for DescriptorBase.
034         */
035        public DescriptorBase()
036        {
037        }
038    
039        /**
040         * @see org.apache.ojb.broker.metadata.AttributeContainer#addAttribute(String, String)
041         */
042        public void addAttribute(String attributeName, String attributeValue)
043        {
044            // Don't allow null attribute names.
045            if (attributeName == null)
046            {
047                return;
048            }
049            // Set up the attribute list
050            if (attributeMap == null)
051            {
052                attributeMap = new HashMap();
053            }
054            // Add the entry.
055            attributeMap.put(attributeName, attributeValue);
056        }
057    
058        /**
059         * @see org.apache.ojb.broker.metadata.AttributeContainer#getAttribute(String, String)
060         */
061        public String getAttribute(String attributeName, String defaultValue)
062        {
063            String result = defaultValue;
064            if (attributeMap != null)
065            {
066                result = (String) attributeMap.get(attributeName);
067                if (result == null)
068                {
069                    result = defaultValue;
070                }
071            }
072            return result;
073        }
074    
075        /**
076         * @see org.apache.ojb.broker.metadata.AttributeContainer#getAttribute(String)
077         */
078        public String getAttribute(String attributeName)
079        {
080            return this.getAttribute(attributeName, null);
081        }
082    
083        /**
084         * Returns the attribute map (name, value) of this descriptor. Note that the
085         * returned map is not modifiable.
086         * 
087         * @return The attributes
088         */
089        public Map getAttributes()
090        {
091            return Collections.unmodifiableMap(attributeMap);
092        }
093    
094        /**
095         * Returns an array of the names of all atributes of this descriptor.
096         * 
097         * @return The list of attribute names (will not be <code>null</code>)
098         */
099        public String[] getAttributeNames()
100        {
101            Set      keys   = (attributeMap == null ? new HashSet() : attributeMap.keySet());
102            String[] result = new String[keys.size()];
103    
104            keys.toArray(result);
105            return result;
106        }
107        
108        public String toString()
109        {
110            StringBuffer buf = new StringBuffer();
111            buf.append("custom attributes [");
112            buf.append(attributeMap);
113            buf.append("]");
114            return buf.toString();
115        }
116    }