Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.wicketstuff.datetime; import java.util.Date; import java.util.Locale; import java.util.TimeZone; import org.apache.wicket.Session; import org.apache.wicket.core.request.ClientInfo; import org.apache.wicket.protocol.http.request.WebClientInfo; import org.apache.wicket.util.convert.ConversionException; import org.apache.wicket.util.convert.IConverter; import org.apache.wicket.util.string.Strings; import org.joda.time.DateTime; import org.joda.time.DateTimeZone; import org.joda.time.format.DateTimeFormatter; /** * Base class for Joda Time based date converters. It contains the logic to parse and format, * optionally taking the time zone difference between clients and the server into account. * <p> * Converters of this class are best suited for per-component use. * </p> * * @author eelcohillenius */ public abstract class DateConverter implements IConverter<Date> { private static final long serialVersionUID = 1L; /** * Whether to apply the time zone difference when interpreting dates. */ private final boolean applyTimeZoneDifference; /** * Construct. </p> When applyTimeZoneDifference is true, the current time is applied on the * parsed date, and the date will be corrected for the time zone difference between the server * and the client. For instance, if I'm in Seattle and the server I'm working on is in * Amsterdam, the server is 9 hours ahead. So, if I'm inputting say 12/24 at a couple of hours * before midnight, at the server it is already 12/25. If this boolean is true, it will be * transformed to 12/25, while the client sees 12/24. </p> * * @param applyTimeZoneDifference * whether to apply the difference in time zones between client and server */ public DateConverter(boolean applyTimeZoneDifference) { this.applyTimeZoneDifference = applyTimeZoneDifference; } /** * @see org.apache.wicket.util.convert.IConverter#convertToObject(java.lang.String, * java.util.Locale) */ @Override public Date convertToObject(String value, Locale locale) { if (Strings.isEmpty(value)) { return null; } DateTimeFormatter format = getFormat(locale); if (format == null) { throw new IllegalStateException("format must be not null"); } if (applyTimeZoneDifference) { TimeZone zone = getClientTimeZone(); DateTime dateTime; // set time zone for client format = format.withZone(getTimeZone()); try { // parse date retaining the time of the submission dateTime = format.parseDateTime(value); } catch (RuntimeException e) { throw newConversionException(e, locale); } // apply the server time zone to the parsed value if (zone != null) { dateTime = dateTime.withZoneRetainFields(DateTimeZone.forTimeZone(zone)); } return dateTime.toDate(); } else { try { DateTime date = format.parseDateTime(value); return date.toDate(); } catch (RuntimeException e) { throw newConversionException(e, locale); } } } /** * Creates a ConversionException and sets additional context information to it. * * @param cause * - {@link RuntimeException} cause * @param locale * - {@link Locale} used to set 'format' variable with localized pattern * @return {@link ConversionException} */ private ConversionException newConversionException(RuntimeException cause, Locale locale) { return new ConversionException(cause).setVariable("format", getDatePattern(locale)); } /** * @see org.apache.wicket.util.convert.IConverter#convertToString(java.lang.Object, * java.util.Locale) */ @Override public String convertToString(Date value, Locale locale) { DateTime dt = new DateTime(value.getTime(), getTimeZone()); DateTimeFormatter format = getFormat(locale); if (applyTimeZoneDifference) { TimeZone zone = getClientTimeZone(); if (zone != null) { // apply time zone to formatter format = format.withZone(DateTimeZone.forTimeZone(zone)); } } return format.print(dt); } /** * Gets whether to apply the time zone difference when interpreting dates. * * </p> When true, the current time is applied on the parsed date, and the date will be * corrected for the time zone difference between the server and the client. For instance, if * I'm in Seattle and the server I'm working on is in Amsterdam, the server is 9 hours ahead. * So, if I'm inputting say 12/24 at a couple of hours before midnight, at the server it is * already 12/25. If this boolean is true, it will be transformed to 12/25, while the client * sees 12/24. </p> * * @return whether to apply the difference in time zones between client and server */ public final boolean getApplyTimeZoneDifference() { return applyTimeZoneDifference; } /** * @param locale * The locale used to convert the value * @return Gets the pattern that is used for printing and parsing */ public abstract String getDatePattern(Locale locale); /** * Gets the client's time zone. * * @return The client's time zone or null */ protected TimeZone getClientTimeZone() { ClientInfo info = Session.get().getClientInfo(); if (info instanceof WebClientInfo) { return ((WebClientInfo) info).getProperties().getTimeZone(); } return null; } /** * @param locale * The locale used to convert the value * * @return formatter The formatter for the current conversion */ protected abstract DateTimeFormatter getFormat(Locale locale); /** * Gets the server time zone. Override this method if you want to fix to a certain time zone, * regardless of what actual time zone the server is in. * * @return The server time zone */ protected DateTimeZone getTimeZone() { return DateTimeZone.getDefault(); } }