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 */
017package org.apache.xbean.propertyeditor;
018
019import 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 */
028public 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}