fastdateformat.java

JAVA 文章管理系统源码

        Object key = new Pair(new Integer(dateStyle), new Integer(timeStyle));
        if (timeZone != null) {
            key = new Pair(key, timeZone);
        }
        if (locale != null) {
            key = new Pair(key, locale);
        }

        FastDateFormat format = (FastDateFormat) cDateTimeInstanceCache.get(key);
        if (format == null) {
            if (locale == null) {
                locale = Locale.getDefault();
            }

            try {
                SimpleDateFormat formatter = (SimpleDateFormat) DateFormat.getDateTimeInstance(dateStyle, timeStyle, locale);
                String pattern = formatter.toPattern();
                format = getInstance(pattern, timeZone, locale);
                cDateTimeInstanceCache.put(key, format);
                
            } catch (ClassCastException ex) {
                throw new IllegalArgumentException("No date time pattern for locale: " + locale);
            }
        }
        return format;
    }

    //-----------------------------------------------------------------------
    /**
     * <p>Gets the time zone display name, using a cache for performance.</p>
     * 
     * @param tz  the zone to query
     * @param daylight  true if daylight savings
     * @param style  the style to use <code>TimeZone.LONG</code>
     *  or <code>TimeZone.SHORT</code>
     * @param locale  the locale to use
     * @return the textual name of the time zone
     */
    static synchronized String getTimeZoneDisplay(TimeZone tz, boolean daylight, int style, Locale locale) {
        Object key = new TimeZoneDisplayKey(tz, daylight, style, locale);
        String value = (String) cTimeZoneDisplayCache.get(key);
        if (value == null) {
            // This is a very slow call, so cache the results.
            value = tz.getDisplayName(daylight, style, locale);
            cTimeZoneDisplayCache.put(key, value);
        }
        return value;
    }

    /**
     * <p>Gets the default pattern.</p>
     * 
     * @return the default pattern
     */
    private static synchronized String getDefaultPattern() {
        if (cDefaultPattern == null) {
            cDefaultPattern = new SimpleDateFormat().toPattern();
        }
        return cDefaultPattern;
    }

    // Constructor
    //-----------------------------------------------------------------------
    /**
     * <p>Constructs a new FastDateFormat.</p>
     * 
     * @param pattern  {@link java.text.SimpleDateFormat} compatible
     *  pattern
     * @param timeZone  time zone to use, <code>null</code> means use
     *  default for <code>Date</code> and value within for
     *  <code>Calendar</code>
     * @param locale  locale, <code>null</code> means use system
     *  default
     * @throws IllegalArgumentException if pattern is invalid or
     *  <code>null</code>
     */
    protected FastDateFormat(String pattern, TimeZone timeZone, Locale locale) {
        super();
        if (pattern == null) {
            throw new IllegalArgumentException("The pattern must not be null");
        }
        mPattern = pattern;
        
        mTimeZoneForced = (timeZone != null);
        if (timeZone == null) {
            timeZone = TimeZone.getDefault();
        }
        mTimeZone = timeZone;
        
        mLocaleForced = (locale != null);
        if (locale == null) {
            locale = Locale.getDefault();
        }
        mLocale = locale;
    }

    /**
     * <p>Initialise the instance for first use.</p>
     */
    protected void init() {
        List rulesList = parsePattern();
        mRules = (Rule[]) rulesList.toArray(new Rule[rulesList.size()]);

        int len = 0;
        for (int i=mRules.length; --i >= 0; ) {
            len += mRules[i].estimateLength();
        }

        mMaxLengthEstimate = len;
    }

    // Parse the pattern
    //-----------------------------------------------------------------------
    /**
     * <p>Returns a list of Rules given a pattern.</p>
     * 
     * @return a <code>List</code> of Rule objects
     * @throws IllegalArgumentException if pattern is invalid
     */
    protected List parsePattern() {
        DateFormatSymbols symbols = new DateFormatSymbols(mLocale);
        List rules = new ArrayList();

        String[] ERAs = symbols.getEras();
        String[] months = symbols.getMonths();
        String[] shortMonths = symbols.getShortMonths();
        String[] weekdays = symbols.getWeekdays();
        String[] shortWeekdays = symbols.getShortWeekdays();
        String[] AmPmStrings = symbols.getAmPmStrings();

        int length = mPattern.length();
        int[] indexRef = new int[1];

        for (int i = 0; i < length; i++) {
            indexRef[0] = i;
            String token = parseToken(mPattern, indexRef);
            i = indexRef[0];

            int tokenLen = token.length();
            if (tokenLen == 0) {
                break;
            }

            Rule rule;
            char c = token.charAt(0);

            switch (c) {
            case 'G': // era designator (text)
                rule = new TextField(Calendar.ERA, ERAs);
                break;
            case 'y': // year (number)
                if (tokenLen >= 4) {
                    rule = UnpaddedNumberField.INSTANCE_YEAR;
                } else {
                    rule = TwoDigitYearField.INSTANCE;
                }
                break;
            case 'M': // month in year (text and number)
                if (tokenLen >= 4) {
                    rule = new TextField(Calendar.MONTH, months);
                } else if (tokenLen == 3) {
                    rule = new TextField(Calendar.MONTH, shortMonths);
                } else if (tokenLen == 2) {
                    rule = TwoDigitMonthField.INSTANCE;
                } else {
                    rule = UnpaddedMonthField.INSTANCE;
                }
                break;
            case 'd': // day in month (number)
                rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
                break;
            case 'h': // hour in am/pm (number, 1..12)
                rule = new TwelveHourField(selectNumberRule(Calendar.HOUR, tokenLen));
                break;
            case 'H': // hour in day (number, 0..23)
                rule = selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen);
                break;
            case 'm': // minute in hour (number)
                rule = selectNumberRule(Calendar.MINUTE, tokenLen);
                break;
            case 's': // second in minute (number)
                rule = selectNumberRule(Calendar.SECOND, tokenLen);
                break;
            case 'S': // millisecond (number)
                rule = selectNumberRule(Calendar.MILLISECOND, tokenLen);
                break;
            case 'E': // day in week (text)
                rule = new TextField(Calendar.DAY_OF_WEEK, tokenLen < 4 ? shortWeekdays : weekdays);
                break;
            case 'D': // day in year (number)
                rule = selectNumberRule(Calendar.DAY_OF_YEAR, tokenLen);
                break;
            case 'F': // day of week in month (number)
                rule = selectNumberRule(Calendar.DAY_OF_WEEK_IN_MONTH, tokenLen);
                break;
            case 'w': // week in year (number)
                rule = selectNumberRule(Calendar.WEEK_OF_YEAR, tokenLen);
                break;
            case 'W': // week in month (number)
                rule = selectNumberRule(Calendar.WEEK_OF_MONTH, tokenLen);
                break;
            case 'a': // am/pm marker (text)
                rule = new TextField(Calendar.AM_PM, AmPmStrings);
                break;
            case 'k': // hour in day (1..24)
                rule = new TwentyFourHourField(selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen));
                break;
            case 'K': // hour in am/pm (0..11)
                rule = selectNumberRule(Calendar.HOUR, tokenLen);
                break;
            case 'z': // time zone (text)
                if (tokenLen >= 4) {
                    rule = new TimeZoneNameRule(mTimeZone, mTimeZoneForced, mLocale, TimeZone.LONG);
                } else {
                    rule = new TimeZoneNameRule(mTimeZone, mTimeZoneForced, mLocale, TimeZone.SHORT);
                }
                break;
            case 'Z': // time zone (value)
                if (tokenLen == 1) {
                    rule = TimeZoneNumberRule.INSTANCE_NO_COLON;
                } else {
                    rule = TimeZoneNumberRule.INSTANCE_COLON;
                }
                break;
            case '\'': // literal text
                String sub = token.substring(1);
                if (sub.length() == 1) {
                    rule = new CharacterLiteral(sub.charAt(0));
                } else {
                    rule = new StringLiteral(sub);
                }
                break;
            default:
                throw new IllegalArgumentException("Illegal pattern component: " + token);
            }

            rules.add(rule);
        }

        return rules;
    }

    /**
     * <p>Performs the parsing of tokens.</p>
     * 
     * @param pattern  the pattern
     * @param indexRef  index references
     * @return parsed token
     */
    protected String parseToken(String pattern, int[] indexRef) {
        StringBuffer buf = new StringBuffer();

        int i = indexRef[0];
        int length = pattern.length();

        char c = pattern.charAt(i);
        if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {
            // Scan a run of the same character, which indicates a time
            // pattern.
            buf.append(c);

            while (i + 1 < length) {
                char peek = pattern.charAt(i + 1);
                if (peek == c) {
                    buf.append(c);
                    i++;
                } else {
                    break;
                }
            }
        } else {
            // This will identify token as text.
            buf.append('\'');

            boolean inLiteral = false;

            for (; i < length; i++) {
                c = pattern.charAt(i);

                if (c == '\'') {
                    if (i + 1 < length && pattern.charAt(i + 1) == '\'') {
                        // '' is treated as escaped '
                        i++;
                        buf.append(c);
                    } else {
                        inLiteral = !inLiteral;
                    }
                } else if (!inLiteral &&
                         (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z')) {
                    i--;
                    break;
                } else {
                    buf.append(c);
                }
            }
        }

        indexRef[0] = i;
        return buf.toString();
    }

    /**
     * <p>Gets an appropriate rule for the padding required.</p>
     * 
     * @param field  the field to get a rule for
     * @param padding  the padding required
     * @return a new rule with the correct padding
     */
    protected NumberRule selectNumberRule(int field, int padding) {
        switch (padding) {
        case 1:
            return new UnpaddedNumberField(field);
        case 2:
            return new TwoDigitNumberField(field);
        default:
            return new PaddedNumberField(field, padding);
        }
    }

    // Format methods
    //-----------------------------------------------------------------------
    /**
     * <p>Format either a <code>Date</code> or a
     * <code>Calendar</code> object.</p>
     * 
     * @param obj  the object to format
     * @param toAppendTo  the buffer to append to
     * @param pos  the position - ignored
     * @return the buffer passed in
     */
    public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos) {
        if (obj instanceof Date) {
            return format((Date) obj, toAppendTo);
        } else if (obj instanceof Calendar) {
            return format((Calendar) obj, toAppendTo);
        } else {
            throw new IllegalArgumentException("Unknown class: " +
                (obj == null ? "<null>" : obj.getClass().getName()));
        }
    }

    /**
     * <p>Formats a <code>Date</code> object.</p>