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 converts an incoming object into a {@link String} object.
021 * <p>
022 * Note that ConvertUtils really is designed to do string-&gt;object conversions, and offers very little support for object-&gt;string conversions. The
023 * ConvertUtils/ConvertUtilsBean methods only select a converter to apply based upon the target type being converted to, and generally assume that the input is
024 * a string (by calling its toString method if needed).
025 * <p>
026 * This class is therefore just a dummy converter that converts its input into a string by calling the input object's toString method and returning that value.
027 * <p>
028 * It is possible to replace this converter with something that has a big if/else statement that selects behavior based on the real type of the object being
029 * converted (or possibly has a map of converters, and looks them up based on the class of the input object). However this is not part of the existing
030 * ConvertUtils framework.
031 *
032 *
033 * @since 1.3
034 */
035public final class StringConverter extends AbstractConverter<String> {
036
037    /**
038     * Constructs a <strong>java.lang.String</strong> <em>Converter</em> that throws a {@code ConversionException} if an error occurs.
039     */
040    public StringConverter() {
041    }
042
043    /**
044     * Constructs a <strong>java.lang.String</strong> <em>Converter</em> that returns a default value if an error occurs.
045     *
046     * @param defaultValue The default value to be returned if the value to be converted is missing or an error occurs converting the value.
047     */
048    public StringConverter(final String defaultValue) {
049        super(defaultValue);
050    }
051
052    /**
053     * Convert the specified input object into an output object of the specified type.
054     *
055     * @param <T>   Target type of the conversion.
056     * @param type  Data type to which this value should be converted.
057     * @param value The input value to be converted.
058     * @return The converted value.
059     * @throws Throwable if an error occurs converting to the specified type
060     * @since 1.8.0
061     */
062    @Override
063    protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable {
064        // We have to support Object, too, because this class is sometimes
065        // used for a standard to Object conversion
066        if (String.class.equals(type) || Object.class.equals(type)) {
067            return type.cast(value.toString());
068        }
069        throw conversionException(type, value);
070    }
071
072    /**
073     * Gets the default type this {@code Converter} handles.
074     *
075     * @return The default type this {@code Converter} handles.
076     * @since 1.8.0
077     */
078    @Override
079    protected Class<String> getDefaultType() {
080        return String.class;
081    }
082
083}