    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.commons.beanutils2.converters;
    018
    019/**
    020 * {@link org.apache.commons.beanutils2.Converter} implementation that handles conversion to and from <strong>java.lang.Enum</strong> objects.
    021 * <p>
    022 * Can be configured to either return a <em>default value</em> or throw a {@code ConversionException} if a conversion error occurs.
    023 * </p>
    024 *
    025 * @param <E> The enum type subclass
    026 * @since 2.0
    027 * @see Enum
    028 */
    029public final class EnumConverter<E extends Enum<E>> extends AbstractConverter<Enum<E>> {
    030
    031    /**
    032     * Constructs a <strong>java.lang.Enum</strong> <em>Converter</em> that throws a {@code ConversionException} if an error occurs.
    033     */
    034    public EnumConverter() {
    035    }
    036
    037    /**
    038     * Constructs a <strong>java.lang.Enum</strong> <em>Converter</em> that returns a default value if an error occurs.
    039     *
    040     * @param defaultValue The default value to be returned if the value to be converted is missing or an error occurs converting the value.
    041     */
    042    public EnumConverter(final Enum<E> defaultValue) {
    043        super(defaultValue);
    044    }
    045
    046    /**
    047     * <p>
    048     * Converts a java.lang.Enum or object into a String.
    049     * </p>
    050     *
    051     * @param <R>   Target type of the conversion.
    052     * @param type  Data type to which this value should be converted.
    053     * @param value The input value to be converted.
    054     * @return The converted value.
    055     * @throws Throwable if an error occurs converting to the specified type
    056     * @since 2.0
    057     */
    058    @SuppressWarnings({ "rawtypes" })
    059    @Override
    060    protected <R> R convertToType(final Class<R> type, final Object value) throws Throwable {
    061        if (Enum.class.isAssignableFrom(type)) {
    062            final String enumValue = String.valueOf(value);
    063            final R[] constants = type.getEnumConstants();
    064            if (constants == null) {
    065                throw conversionException(type, value);
    066            }
    067            for (final R candidate : constants) {
    068                if (((Enum) candidate).name().equalsIgnoreCase(enumValue)) {
    069                    return candidate;
    070                }
    071            }
    072        }
    073
    074        throw conversionException(type, value);
    075    }
    076
    077    /**
    078     * Gets the default type this {@code Converter} handles.
    079     *
    080     * @return The default type this {@code Converter} handles.
    081     * @since 2.0
    082     */
    083    @SuppressWarnings({ "unchecked", "rawtypes" })
    084    @Override
    085    protected Class<Enum<E>> getDefaultType() {
    086        return (Class) Enum.class;
    087    }
    088
    089}