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.xbean.propertyeditor;
018    
019    import java.beans.PropertyEditorSupport;
020    
021    /**
022     * A base class for converters.  This class handles all converter methods, and redirects all conversion requests to
023     * toStringImpl and toObjectImpl.  These methods can assume that the supplied value or text is never null, and that
024     * type checking has been applied to the value.
025     *
026     * @version $Rev: 6680 $
027     */
028    public abstract class AbstractConverter extends PropertyEditorSupport implements Converter {
029        private final Class type;
030    
031        /**
032         * Creates an abstract converter for the specified type.
033         *
034         * @param type type of the property editor
035         */
036        protected AbstractConverter(Class type) {
037            super();
038            if (type == null) throw new NullPointerException("type is null");
039            this.type = type;
040        }
041    
042        public final Class getType() {
043            return type;
044        }
045    
046        public final String getAsText() {
047            Object value = super.getValue();
048            String text = toString(value);
049            return text;
050        }
051    
052        public final void setAsText(String text) {
053            Object value = toObject(text.trim());
054            super.setValue(value);
055        }
056    
057        public final Object getValue() {
058            Object value = super.getValue();
059            return value;
060        }
061    
062        public final void setValue(Object value) {
063            // Don't validate the type. Type validation is not required by spec and some setters (e.g. Spring) expect this.
064            super.setValue(value);
065        }
066    
067        public final String toString(Object value) {
068            if (value == null) {
069                return null;
070            }
071            // Don't validate the type. Type validation is not required by spec and some setters (e.g. Spring) expect this.
072            return toStringImpl(value);
073        }
074    
075        public final Object toObject(String text) {
076            if (text == null) {
077                return null;
078            }
079    
080            Object value = toObjectImpl(text.trim());
081            return value;
082        }
083    
084        /**
085         * Converts the supplied object to text.  The supplied object will always be an instance of the editor type, and
086         * specifically will never be null or a String (unless this is the String editor).
087         *
088         * @param value an instance of the editor type
089         * @return the text equivalent of the value
090         */
091        protected String toStringImpl(Object value) {
092            String text = value.toString();
093            return text;
094        }
095    
096        /**
097         * Converts the supplied text in to an instance of the editor type.  The text will never be null, and trim() will
098         * already have been called.
099         *
100         * @param text the text to convert
101         * @return an instance of the editor type
102         */
103        protected abstract Object toObjectImpl(String text);
104    }