org.springframework.binding.convert.converters.StringToDate.java Source code

Introduction

Here is the source code for org.springframework.binding.convert.converters.StringToDate.java

Source

/*
 * Copyright 2004-2012 the original author or authors.
 *
 * 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 org.springframework.binding.convert.converters;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.util.StringUtils;

/**
 * A formatter for {@link Date} types. Allows the configuration of an explicit date pattern and locale.
 * @see SimpleDateFormat
 * @author Keith Donald
 */
public class StringToDate extends StringToObject {

    private static Log logger = LogFactory.getLog(StringToDate.class);

    /**
     * The default date pattern.
     */
    private static final String DEFAULT_PATTERN = "yyyy-MM-dd";

    private String pattern;

    private Locale locale;

    public StringToDate() {
        super(Date.class);
    }

    /**
     * The pattern to use to format date values. If not specified, the default pattern 'yyyy-MM-dd' is used.
     * @return the date formatting pattern
     */
    public String getPattern() {
        return pattern;
    }

    /**
     * Sets the pattern to use to format date values.
     * @param pattern the date formatting pattern
     */
    public void setPattern(String pattern) {
        this.pattern = pattern;
    }

    /**
     * The locale to use in formatting date values. If not specified, the locale of the current thread is used.
     * @see LocaleContextHolder#getLocale()
     * @return the locale
     */
    public Locale getLocale() {
        return locale;
    }

    /**
     * Sets the locale to use in formatting date values.
     * @param locale the locale
     */
    public void setLocale(Locale locale) {
        this.locale = locale;
    }

    public Object toObject(String string, Class<?> targetClass) throws Exception {
        if (!StringUtils.hasText(string)) {
            return null;
        }
        DateFormat dateFormat = getDateFormat();
        try {
            return dateFormat.parse(string);
        } catch (ParseException e) {
            throw new InvalidFormatException(string, getPattern(dateFormat), e);
        }
    }

    public String toString(Object target) throws Exception {
        Date date = (Date) target;
        if (date == null) {
            return "";
        }
        return getDateFormat().format(date);
    }

    // subclassing hookings

    protected DateFormat getDateFormat() {
        Locale locale = determineLocale(this.locale);
        DateFormat format = DateFormat.getDateInstance(DateFormat.SHORT, locale);
        format.setLenient(false);
        if (format instanceof SimpleDateFormat) {
            String pattern = determinePattern(this.pattern);
            ((SimpleDateFormat) format).applyPattern(pattern);
        } else {
            logger.warn("Unable to apply format pattern '" + pattern
                    + "'; Returned DateFormat is not a SimpleDateFormat");
        }
        return format;
    }

    // internal helpers

    private String determinePattern(String pattern) {
        return pattern != null ? pattern : DEFAULT_PATTERN;
    }

    private Locale determineLocale(Locale locale) {
        return locale != null ? locale : LocaleContextHolder.getLocale();
    }

    private String getPattern(DateFormat format) {
        if (format instanceof SimpleDateFormat) {
            return ((SimpleDateFormat) format).toPattern();
        } else {
            logger.warn("Pattern string cannot be determined because DateFormat is not a SimpleDateFormat");
            return "defaultDateFormatInstance";
        }
    }

}