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.dbutils.wrappers;
018    
019    import java.lang.reflect.InvocationHandler;
020    import java.lang.reflect.Method;
021    import java.sql.ResultSet;
022    
023    import org.apache.commons.dbutils.ProxyFactory;
024    
025    /**
026     * Wraps a <code>ResultSet</code> to trim strings returned by the
027     * <code>getString()</code> and <code>getObject()</code> methods.
028     * 
029     * <p>
030     * Usage Example:
031     * This example shows how to decorate ResultSets so processing continues as 
032     * normal but all Strings are trimmed before being returned from the 
033     * <code>ResultSet</code>.
034     * </p>
035     * 
036     * <pre>
037     * ResultSet rs = // somehow get a ResultSet;
038     * 
039     * // Substitute wrapped ResultSet with additional behavior for real ResultSet
040     * rs = StringTrimmedResultSet.wrap(rs);
041     * 
042     * // Pass wrapped ResultSet to processor
043     * List list = new BasicRowProcessor().toBeanList(rs);
044     * </pre>
045     */
046    public class StringTrimmedResultSet implements InvocationHandler {
047    
048        /**
049         * The factory to create proxies with.
050         */
051        private static final ProxyFactory factory = ProxyFactory.instance();
052    
053        /**
054         * Wraps the <code>ResultSet</code> in an instance of this class.  This is
055         * equivalent to:
056         * <pre>
057         * ProxyFactory.instance().createResultSet(new StringTrimmedResultSet(rs));
058         * </pre>
059         * 
060         * @param rs The <code>ResultSet</code> to wrap.
061         * @return wrapped ResultSet
062         */
063        public static ResultSet wrap(ResultSet rs) {
064            return factory.createResultSet(new StringTrimmedResultSet(rs));
065        }
066    
067        /**
068         * The wrapped result. 
069         */
070        private final ResultSet rs;
071    
072        /**
073         * Constructs a new instance of <code>StringTrimmedResultSet</code>
074         * to wrap the specified <code>ResultSet</code>.
075         * @param rs ResultSet to wrap
076         */
077        public StringTrimmedResultSet(ResultSet rs) {
078            super();
079            this.rs = rs;
080        }
081    
082        /**
083         * Intercept calls to the <code>getString()</code> and 
084         * <code>getObject()</code> methods and trim any Strings before they're
085         * returned.
086         * 
087         * @throws Throwable
088         * @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])
089         */
090        public Object invoke(Object proxy, Method method, Object[] args)
091            throws Throwable {
092    
093            Object result = method.invoke(this.rs, args);
094    
095            if (method.getName().equals("getObject")
096                || method.getName().equals("getString")) {
097    
098                if (result instanceof String) {
099                    result = ((String) result).trim();
100                }
101            }
102    
103            return result;
104        }
105    
106    }