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 *      https://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.beanutils.converters;
018
019/**
020 * {@link org.apache.commons.beanutils.Converter}
021 * implementation that converts an incoming
022 * object into a <code>java.lang.String</code> object.
023 * <p>
024 * Note that ConvertUtils really is designed to do string to object conversions,
025 * and offers very little support for object to string conversions. The
026 * ConvertUtils/ConvertUtilsBean methods only select a converter to apply
027 * based upon the target type being converted to, and generally assume that
028 * the input is a string (by calling its toString method if needed).
029 * <p>
030 * This class is therefore just a dummy converter that converts its input
031 * into a string by calling the input object's toString method and returning
032 * that value.
033 * <p>
034 * It is possible to replace this converter with something that has a big
035 * if/else statement that selects behavior based on the real type of the
036 * object being converted (or possibly has a map of converters, and looks
037 * them up based on the class of the input object). However this is not part
038 * of the existing ConvertUtils framework.
039 *
040 *
041 * @since 1.3
042 */
043public final class StringConverter extends AbstractConverter {
044
045    /**
046     * Construct a <strong>java.lang.String</strong> <em>Converter</em> that throws
047     * a <code>ConversionException</code> if an error occurs.
048     */
049    public StringConverter() {
050    }
051
052    /**
053     * Construct a <strong>java.lang.String</strong> <em>Converter</em> that returns
054     * a default value if an error occurs.
055     *
056     * @param defaultValue The default value to be returned
057     * if the value to be converted is missing or an error
058     * occurs converting the value.
059     */
060    public StringConverter(final Object defaultValue) {
061        super(defaultValue);
062    }
063
064    /**
065     * Convert the specified input object into an output object of the
066     * specified type.
067     *
068     * @param <T> Target type of the conversion.
069     * @param type Data type to which this value should be converted.
070     * @param value The input value to be converted.
071     * @return The converted value.
072     * @throws Throwable if an error occurs converting to the specified type
073     * @since 1.8.0
074     */
075    @Override
076    protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable {
077        // We have to support Object, too, because this class is sometimes
078        // used for a standard to Object conversion
079        if (String.class.equals(type) || Object.class.equals(type)) {
080            return type.cast(value.toString());
081        }
082        throw conversionException(type, value);
083    }
084
085    /**
086     * Return the default type this <code>Converter</code> handles.
087     *
088     * @return The default type this <code>Converter</code> handles.
089     * @since 1.8.0
090     */
091    @Override
092    protected Class<?> getDefaultType() {
093        return String.class;
094    }
095
096}