Java tutorial
/* * Copyright 2016 The Netty Project * * The Netty Project 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 io.netty.handler.codec; import static io.netty.util.internal.ObjectUtil.checkNotNull; import io.netty.util.AsciiString; import io.netty.util.concurrent.FastThreadLocal; import java.util.BitSet; import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar; import java.util.TimeZone; /** * A formatter for HTTP header dates, such as "Expires" and "Date" headers, or "expires" field in "Set-Cookie". * * On the parsing side, it honors RFC6265 (so it supports RFC1123). * Note that: * <ul> * <li>Day of week is ignored and not validated</li> * <li>Timezone is ignored, as RFC6265 assumes UTC</li> * </ul> * If you're looking for a date format that validates day of week, or supports other timezones, consider using * java.util.DateTimeFormatter.RFC_1123_DATE_TIME. * * On the formatting side, it uses RFC1123 format. * * @see <a href="https://tools.ietf.org/html/rfc6265#section-5.1.1">RFC6265</a> for the parsing side * @see <a href="https://tools.ietf.org/html/rfc1123#page-55">RFC1123</a> for the encoding side. */ public final class DateFormatter { private static final BitSet DELIMITERS = new BitSet(); static { DELIMITERS.set(0x09); for (char c = 0x20; c <= 0x2F; c++) { DELIMITERS.set(c); } for (char c = 0x3B; c <= 0x40; c++) { DELIMITERS.set(c); } for (char c = 0x5B; c <= 0x60; c++) { DELIMITERS.set(c); } for (char c = 0x7B; c <= 0x7E; c++) { DELIMITERS.set(c); } } private static final String[] DAY_OF_WEEK_TO_SHORT_NAME = new String[] { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; private static final String[] CALENDAR_MONTH_TO_SHORT_NAME = new String[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; private static final FastThreadLocal<DateFormatter> INSTANCES = new FastThreadLocal<DateFormatter>() { @Override protected DateFormatter initialValue() { return new DateFormatter(); } }; /** * Parse some text into a {@link Date}, according to RFC6265 * @param txt text to parse * @return a {@link Date}, or null if text couldn't be parsed */ public static Date parseHttpDate(CharSequence txt) { return parseHttpDate(txt, 0, txt.length()); } /** * Parse some text into a {@link Date}, according to RFC6265 * @param txt text to parse * @param start the start index inside {@code txt} * @param end the end index inside {@code txt} * @return a {@link Date}, or null if text couldn't be parsed */ public static Date parseHttpDate(CharSequence txt, int start, int end) { int length = end - start; if (length == 0) { return null; } else if (length < 0) { throw new IllegalArgumentException("Can't have end < start"); } else if (length > 64) { throw new IllegalArgumentException( "Can't parse more than 64 chars," + "looks like a user error or a malformed header"); } return formatter().parse0(checkNotNull(txt, "txt"), start, end); } /** * Format a {@link Date} into RFC1123 format * @param date the date to format * @return a RFC1123 string */ public static String format(Date date) { return formatter().format0(checkNotNull(date, "date")); } /** * Append a {@link Date} to a {@link StringBuilder} into RFC1123 format * @param date the date to format * @param sb the StringBuilder * @return the same StringBuilder */ public static StringBuilder append(Date date, StringBuilder sb) { return formatter().append0(checkNotNull(date, "date"), checkNotNull(sb, "sb")); } private static DateFormatter formatter() { DateFormatter formatter = INSTANCES.get(); formatter.reset(); return formatter; } // delimiter = %x09 / %x20-2F / %x3B-40 / %x5B-60 / %x7B-7E private static boolean isDelim(char c) { return DELIMITERS.get(c); } private static boolean isDigit(char c) { return c >= 48 && c <= 57; } private static int getNumericalValue(char c) { return c - 48; } private final GregorianCalendar cal = new GregorianCalendar(TimeZone.getTimeZone("UTC")); private final StringBuilder sb = new StringBuilder(29); // Sun, 27 Nov 2016 19:37:15 GMT private boolean timeFound; private int hours; private int minutes; private int seconds; private boolean dayOfMonthFound; private int dayOfMonth; private boolean monthFound; private int month; private boolean yearFound; private int year; private DateFormatter() { reset(); } public void reset() { timeFound = false; hours = -1; minutes = -1; seconds = -1; dayOfMonthFound = false; dayOfMonth = -1; monthFound = false; month = -1; yearFound = false; year = -1; cal.clear(); sb.setLength(0); } private boolean tryParseTime(CharSequence txt, int tokenStart, int tokenEnd) { int len = tokenEnd - tokenStart; // h:m:s to hh:mm:ss if (len < 5 || len > 8) { return false; } int localHours = -1; int localMinutes = -1; int localSeconds = -1; int currentPartNumber = 0; int currentPartValue = 0; int numDigits = 0; for (int i = tokenStart; i < tokenEnd; i++) { char c = txt.charAt(i); if (isDigit(c)) { currentPartValue = currentPartValue * 10 + getNumericalValue(c); if (++numDigits > 2) { return false; // too many digits in this part } } else if (c == ':') { if (numDigits == 0) { // no digits between separators return false; } switch (currentPartNumber) { case 0: // flushing hours localHours = currentPartValue; break; case 1: // flushing minutes localMinutes = currentPartValue; break; default: // invalid, too many : return false; } currentPartValue = 0; currentPartNumber++; numDigits = 0; } else { // invalid char return false; } } if (numDigits > 0) { // pending seconds localSeconds = currentPartValue; } if (localHours >= 0 && localMinutes >= 0 && localSeconds >= 0) { hours = localHours; minutes = localMinutes; seconds = localSeconds; return true; } return false; } private boolean tryParseDayOfMonth(CharSequence txt, int tokenStart, int tokenEnd) { int len = tokenEnd - tokenStart; if (len == 1) { char c0 = txt.charAt(tokenStart); if (isDigit(c0)) { dayOfMonth = getNumericalValue(c0); return true; } } else if (len == 2) { char c0 = txt.charAt(tokenStart); char c1 = txt.charAt(tokenStart + 1); if (isDigit(c0) && isDigit(c1)) { dayOfMonth = getNumericalValue(c0) * 10 + getNumericalValue(c1); return true; } } return false; } private boolean tryParseMonth(CharSequence txt, int tokenStart, int tokenEnd) { int len = tokenEnd - tokenStart; if (len != 3) { return false; } char monthChar1 = AsciiString.toLowerCase(txt.charAt(tokenStart)); char monthChar2 = AsciiString.toLowerCase(txt.charAt(tokenStart + 1)); char monthChar3 = AsciiString.toLowerCase(txt.charAt(tokenStart + 2)); if (monthChar1 == 'j' && monthChar2 == 'a' && monthChar3 == 'n') { month = Calendar.JANUARY; } else if (monthChar1 == 'f' && monthChar2 == 'e' && monthChar3 == 'b') { month = Calendar.FEBRUARY; } else if (monthChar1 == 'm' && monthChar2 == 'a' && monthChar3 == 'r') { month = Calendar.MARCH; } else if (monthChar1 == 'a' && monthChar2 == 'p' && monthChar3 == 'r') { month = Calendar.APRIL; } else if (monthChar1 == 'm' && monthChar2 == 'a' && monthChar3 == 'y') { month = Calendar.MAY; } else if (monthChar1 == 'j' && monthChar2 == 'u' && monthChar3 == 'n') { month = Calendar.JUNE; } else if (monthChar1 == 'j' && monthChar2 == 'u' && monthChar3 == 'l') { month = Calendar.JULY; } else if (monthChar1 == 'a' && monthChar2 == 'u' && monthChar3 == 'g') { month = Calendar.AUGUST; } else if (monthChar1 == 's' && monthChar2 == 'e' && monthChar3 == 'p') { month = Calendar.SEPTEMBER; } else if (monthChar1 == 'o' && monthChar2 == 'c' && monthChar3 == 't') { month = Calendar.OCTOBER; } else if (monthChar1 == 'n' && monthChar2 == 'o' && monthChar3 == 'v') { month = Calendar.NOVEMBER; } else if (monthChar1 == 'd' && monthChar2 == 'e' && monthChar3 == 'c') { month = Calendar.DECEMBER; } else { return false; } return true; } private boolean tryParseYear(CharSequence txt, int tokenStart, int tokenEnd) { int len = tokenEnd - tokenStart; if (len == 2) { char c0 = txt.charAt(tokenStart); char c1 = txt.charAt(tokenStart + 1); if (isDigit(c0) && isDigit(c1)) { year = getNumericalValue(c0) * 10 + getNumericalValue(c1); return true; } } else if (len == 4) { char c0 = txt.charAt(tokenStart); char c1 = txt.charAt(tokenStart + 1); char c2 = txt.charAt(tokenStart + 2); char c3 = txt.charAt(tokenStart + 3); if (isDigit(c0) && isDigit(c1) && isDigit(c2) && isDigit(c3)) { year = getNumericalValue(c0) * 1000 + getNumericalValue(c1) * 100 + getNumericalValue(c2) * 10 + getNumericalValue(c3); return true; } } return false; } private boolean parseToken(CharSequence txt, int tokenStart, int tokenEnd) { // return true if all parts are found if (!timeFound) { timeFound = tryParseTime(txt, tokenStart, tokenEnd); if (timeFound) { return dayOfMonthFound && monthFound && yearFound; } } if (!dayOfMonthFound) { dayOfMonthFound = tryParseDayOfMonth(txt, tokenStart, tokenEnd); if (dayOfMonthFound) { return timeFound && monthFound && yearFound; } } if (!monthFound) { monthFound = tryParseMonth(txt, tokenStart, tokenEnd); if (monthFound) { return timeFound && dayOfMonthFound && yearFound; } } if (!yearFound) { yearFound = tryParseYear(txt, tokenStart, tokenEnd); } return timeFound && dayOfMonthFound && monthFound && yearFound; } private Date parse0(CharSequence txt, int start, int end) { boolean allPartsFound = parse1(txt, start, end); return allPartsFound && normalizeAndValidate() ? computeDate() : null; } private boolean parse1(CharSequence txt, int start, int end) { // return true if all parts are found int tokenStart = -1; for (int i = start; i < end; i++) { char c = txt.charAt(i); if (isDelim(c)) { if (tokenStart != -1) { // terminate token if (parseToken(txt, tokenStart, i)) { return true; } tokenStart = -1; } } else if (tokenStart == -1) { // start new token tokenStart = i; } } // terminate trailing token return tokenStart != -1 && parseToken(txt, tokenStart, txt.length()); } private boolean normalizeAndValidate() { if (dayOfMonth < 1 || dayOfMonth > 31 || hours > 23 || minutes > 59 || seconds > 59) { return false; } if (year >= 70 && year <= 99) { year += 1900; } else if (year >= 0 && year < 70) { year += 2000; } else if (year < 1601) { // invalid value return false; } return true; } private Date computeDate() { cal.set(Calendar.DAY_OF_MONTH, dayOfMonth); cal.set(Calendar.MONTH, month); cal.set(Calendar.YEAR, year); cal.set(Calendar.HOUR_OF_DAY, hours); cal.set(Calendar.MINUTE, minutes); cal.set(Calendar.SECOND, seconds); return cal.getTime(); } private String format0(Date date) { append0(date, sb); return sb.toString(); } private StringBuilder append0(Date date, StringBuilder sb) { cal.setTime(date); sb.append(DAY_OF_WEEK_TO_SHORT_NAME[cal.get(Calendar.DAY_OF_WEEK) - 1]).append(", "); sb.append(cal.get(Calendar.DAY_OF_MONTH)).append(' '); sb.append(CALENDAR_MONTH_TO_SHORT_NAME[cal.get(Calendar.MONTH)]).append(' '); sb.append(cal.get(Calendar.YEAR)).append(' '); appendZeroLeftPadded(cal.get(Calendar.HOUR_OF_DAY), sb).append(':'); appendZeroLeftPadded(cal.get(Calendar.MINUTE), sb).append(':'); return appendZeroLeftPadded(cal.get(Calendar.SECOND), sb).append(" GMT"); } private static StringBuilder appendZeroLeftPadded(int value, StringBuilder sb) { if (value < 10) { sb.append('0'); } return sb.append(value); } }