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.apache.commons.lang; import java.text.DateFormat; import java.text.DateFormatSymbols; import java.text.ParseException; import java.util.Calendar; import java.util.Date; import java.util.Locale; /* * This class was created to hold the parseCVS method extracted from DateUtils in commons-lang. * The code was originally submitted by Serge Knystautas sergek@lokitech.com. It was never * fully implemented, and has been moved to the sandbox for further development. Recent discussion * from the commons-dev mailing list: * http://marc.theaimsgroup.com/?l=jakarta-commons-dev&m=108904098032038&w=2 * Moving the code to the sandbox satisfies bug is a temporary solution to * http://issues.apache.org/bugzilla/show_bug.cgi?id=22172 but this issue needs to be considered * when the class/method is further developed. */ public class DateFormatter { /** * <p>Parses a date string formatted in CVS format.</p> * * @param dateStr the date to parse * @return the parsed date * @throws IllegalArgumentException if the date cannot be parsed */ public static Calendar parseCVS(String dateStr) { if (dateStr == null) { throw new IllegalArgumentException("The date must not be null"); } //Get the symbol names DateFormatSymbols symbols = new DateFormatSymbols(Locale.ENGLISH); DateFormat[] dateFormats = new DateFormat[0]; //Prep the string to parse String value = dateStr.toLowerCase().trim(); //Get the current date/time Calendar now = Calendar.getInstance(); if (value.endsWith(" ago")) { //If this was a date that was "ago" the current time... //Strip out the ' ago' part value = value.substring(0, value.length() - 4); //Split the value and unit int start = value.indexOf(" "); if (start < 0) { throw new IllegalArgumentException("Could not find space in between value and unit"); } String unit = value.substring(start + 1); value = value.substring(0, start); //We support "a week", so we need to parse the value as "a" int val = 0; if (value.equals("a") || value.equals("an")) { val = 1; } else { val = Integer.parseInt(value); } //Determine the unit if (unit.equals("milliseconds") || unit.equals("millisecond")) { now.add(Calendar.MILLISECOND, -val); } else if (unit.equals("seconds") || unit.equals("second")) { now.add(Calendar.SECOND, -val); } else if (unit.equals("minutes") || unit.equals("minute")) { now.add(Calendar.MINUTE, -val); } else if (unit.equals("hours") || unit.equals("hour")) { now.add(Calendar.HOUR, -val); } else if (unit.equals("days") || unit.equals("day")) { now.add(Calendar.DATE, -val); } else if (unit.equals("weeks") || unit.equals("week")) { now.add(Calendar.DATE, -val * 7); } else if (unit.equals("fortnights") || unit.equals("fortnight")) { now.add(Calendar.DATE, -val * 14); } else if (unit.equals("months") || unit.equals("month")) { now.add(Calendar.MONTH, -val); } else if (unit.equals("years") || unit.equals("year")) { now.add(Calendar.YEAR, -val); } else { throw new IllegalArgumentException("We do not understand that many units ago"); } return now; } else if (value.startsWith("last ")) { //If this was the last time a certain field was met //Strip out the 'last ' part value = value.substring(5); //Get the current date/time String[] strings = symbols.getWeekdays(); for (int i = 0; i < strings.length; i++) { if (value.equalsIgnoreCase(strings[i])) { //How many days after Sunday int daysAgo = now.get(Calendar.DAY_OF_WEEK) - i; if (daysAgo <= 0) { daysAgo += 7; } now.add(Calendar.DATE, -daysAgo); return now; } } strings = symbols.getMonths(); for (int i = 0; i < strings.length; i++) { if (value.equalsIgnoreCase(strings[i])) { //How many days after January int monthsAgo = now.get(Calendar.MONTH) - i; if (monthsAgo <= 0) { monthsAgo += 12; } now.add(Calendar.MONTH, -monthsAgo); return now; } } if (value.equals("week")) { now.add(Calendar.DATE, -7); return now; } throw new IllegalArgumentException("We do not understand that last units"); } else if (value.equals("yesterday")) { now.add(Calendar.DATE, -1); return now; } else if (value.equals("tomorrow")) { now.add(Calendar.DATE, 1); return now; } //Try to parse the date a number of different ways for (int i = 0; i < dateFormats.length; i++) { try { Date datetime = dateFormats[i].parse(dateStr); Calendar cal = Calendar.getInstance(); cal.setTime(datetime); return cal; } catch (ParseException pe) { //we ignore this and just keep trying } } throw new IllegalArgumentException("Unable to parse '" + dateStr + "'."); } }