001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  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    package org.apache.commons.modeler.modules;
018    
019    import java.io.File;
020    import java.io.FileInputStream;
021    import java.io.IOException;
022    import java.io.InputStream;
023    import java.net.URL;
024    import java.util.List;
025    
026    import javax.management.ObjectName;
027    
028    import org.apache.commons.modeler.Registry;
029    
030    /** Source for descriptor data. More sources can be added.
031     *
032     */
033    public class ModelerSource {
034        protected Object source;
035        protected String location;
036    
037        /** Load data, returns a list of items. 
038         * 
039         * @param registry
040         * @param location
041         * @param type
042         * @param source Introspected object or some other source
043         * @throws Exception
044         */ 
045        public List loadDescriptors( Registry registry, String location,
046                                     String type, Object source)
047                throws Exception
048        {
049            // TODO
050            return null;
051        }
052        
053        /** Callback from the BaseMBean to notify that an attribute has changed.
054         * Can be used to implement persistence.
055         * 
056         * @param oname
057         * @param name
058         * @param value
059         */ 
060        public void updateField( ObjectName oname, String name, 
061                                 Object value ) {
062            // nothing by default 
063        }
064    
065        public void store() {
066            // nothing
067        }
068    
069        protected InputStream getInputStream() throws IOException {
070            if( source instanceof URL ) {
071                URL url=(URL)source;
072                location=url.toString();
073                return url.openStream();
074            } else if( source instanceof File ) {
075                location=((File)source).getAbsolutePath();
076                return new FileInputStream((File)source);            
077            } else if( source instanceof String) {
078                location=(String)source;
079                return new FileInputStream((String)source);            
080            } else if( source instanceof InputStream ) {
081                return (InputStream)source;
082            } 
083            return null;
084        }
085    
086    }