vaadin-framework/server/src/main/java/com/vaadin/data/util/converter/StringToDateConverter.java

/*
 * Copyright 2000-2014 Vaadin Ltd.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.vaadin.data.util.converter;

import java.text.DateFormat;
import java.text.ParsePosition;
import java.util.Date;
import java.util.Locale;

/**
 * A converter that converts from {@link Date} to {@link String} and back. Uses
 * the given locale and {@link DateFormat} for formatting and parsing.
 * <p>
 * Leading and trailing white spaces are ignored when converting from a String.
 * </p>
 * <p>
 * Override and overwrite {@link #getFormat(Locale)} to use a different format.
 * </p>
 * 
 * @author Vaadin Ltd
 * @since 7.0
 */
public class StringToDateConverter implements Converter<String, Date> {

    /**
     * Returns the format used by
     * {@link #convertToPresentation(Date, Class,Locale)} and
     * {@link #convertToModel(String, Class, Locale)}.
     * 
     * @param locale
     *            The locale to use
     * @return A DateFormat instance
     */
    protected DateFormat getFormat(Locale locale) {
        if (locale == null) {
            locale = Locale.getDefault();
        }

        DateFormat f = DateFormat.getDateTimeInstance(DateFormat.MEDIUM,
                DateFormat.MEDIUM, locale);
        f.setLenient(false);
        return f;
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.vaadin.data.util.converter.Converter#convertToModel(java.lang.Object,
     * java.lang.Class, java.util.Locale)
     */
    @Override
    public Date convertToModel(String value, Class<? extends Date> targetType,
            Locale locale)
            throws com.vaadin.data.util.converter.Converter.ConversionException {
        if (targetType != getModelType()) {
            throw new ConversionException("Converter only supports "
                    + getModelType().getName() + " (targetType was "
                    + targetType.getName() + ")");
        }

        if (value == null) {
            return null;
        }

        // Remove leading and trailing white space
        value = value.trim();

        ParsePosition parsePosition = new ParsePosition(0);
        Date parsedValue = getFormat(locale).parse(value, parsePosition);
        if (parsePosition.getIndex() != value.length()) {
            throw new ConversionException("Could not convert '" + value
                    + "' to " + getModelType().getName());
        }

        return parsedValue;
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.vaadin.data.util.converter.Converter#convertToPresentation(java.lang
     * .Object, java.lang.Class, java.util.Locale)
     */
    @Override
    public String convertToPresentation(Date value,
            Class<? extends String> targetType, Locale locale)
            throws com.vaadin.data.util.converter.Converter.ConversionException {
        if (value == null) {
            return null;
        }

        return getFormat(locale).format(value);
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.vaadin.data.util.converter.Converter#getModelType()
     */
    @Override
    public Class<Date> getModelType() {
        return Date.class;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.vaadin.data.util.converter.Converter#getPresentationType()
     */
    @Override
    public Class<String> getPresentationType() {
        return String.class;
    }

}