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.activemq.console.filter;
018    
019    import java.util.ArrayList;
020    import java.util.Iterator;
021    import java.util.List;
022    
023    public abstract class ResultTransformFilter implements QueryFilter {
024        private QueryFilter next;
025    
026        /**
027         * Constructs a query filter that transform the format of the query result
028         * 
029         * @param next - the query filter to retrieve the results from
030         */
031        protected ResultTransformFilter(QueryFilter next) {
032            this.next = next;
033        }
034    
035        /**
036         * Transforms the queried results to a collection of different objects
037         * 
038         * @param query - the query string
039         * @return collections of transformed objects
040         * @throws Exception
041         */
042        public List query(String query) throws Exception {
043            return transformList(next.query(query));
044        }
045    
046        /**
047         * Transforms the queried results to a collection of different objects
048         * 
049         * @param queries - the query map
050         * @return collections of transformed objects
051         * @throws Exception
052         */
053        public List<Object> query(List queries) throws Exception {
054            return transformList(next.query(queries));
055        }
056    
057        /**
058         * Transforms a collection to a collection of different objects.
059         * 
060         * @param result - the collection to transform
061         * @return collection of properties objects
062         */
063        protected List<Object> transformList(List<Object> result) throws Exception {
064            List<Object> props = new ArrayList<Object>();
065    
066            for (Iterator<Object> i = result.iterator(); i.hasNext();) {
067                props.add(transformElement(i.next()));
068            }
069    
070            return props;
071        }
072    
073        /**
074         * Transform a result object
075         * 
076         * @param obj - the object instance to transform
077         * @return the transformed object
078         */
079        protected abstract Object transformElement(Object obj) throws Exception;
080    
081    }