datehelper.java

JavaeeTutorial5的源代码。

/*
 * Copyright 2007 Sun Microsystems, Inc.
 * All rights reserved.  You may not modify, use,
 * reproduce, or distribute this software except in
 * compliance with  the terms of the License at:
 * http://developer.sun.com/berkeley_license.html
 */


package com.sun.cb.common;

import java.util.*;
import java.text.SimpleDateFormat;


/**
 * This class contains helper methods for dealing with
 * Date objects.
 */
public final class DateHelper {
    public static final Date getDate(
        int year,
        int month,
        int day,
        int hour,
        int minute) {
        // returns a Date with the specified time elements
        Calendar cal = new GregorianCalendar(
                    year,
                    intToCalendarMonth(month),
                    day,
                    hour,
                    minute);

        return cal.getTime();
    } // getDate

    public static final Date getDate(
        int year,
        int month,
        int day) {
        // returns a Date with the specified time elements,
        // with the hour and minutes both set to 0 (midnight)
        Calendar cal = new GregorianCalendar(
                    year,
                    intToCalendarMonth(month),
                    day);

        return cal.getTime();
    } // getDate

    public static final Date addDays(
        Date target,
        int days) {
        // returns a Date that is the sum of the target Date
        // and the specified number of days;
        // to subtract days from the target Date, the days
        // argument should be negative
        long msPerDay = 1000 * 60 * 60 * 24;
        long msTarget = target.getTime();
        long msSum = msTarget + (msPerDay * days);
        Date result = new Date();
        result.setTime(msSum);

        return result;
    } // addDays

    public static int dayDiff(
        Date first,
        Date second) {
        // returns the difference, in days, between the first
        // and second Date arguments
        long msPerDay = 1000 * 60 * 60 * 24;
        long diff = (first.getTime() / msPerDay)
            - (second.getTime() / msPerDay);
        Long convertLong = new Long(diff);

        return convertLong.intValue();
    } // dayDiff

    public static int getYear(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        return cal.get(Calendar.YEAR);
    } // getYear

    public static int getMonth(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        int calendarMonth = cal.get(Calendar.MONTH);

        return calendarMonthToInt(calendarMonth);
    } // getMonth

    public static int getDay(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        return cal.get(Calendar.DAY_OF_MONTH);
    } // getDay

    public static int getHour(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        return cal.get(Calendar.HOUR_OF_DAY);
    } // getHour

    public static int getMinute(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        return cal.get(Calendar.MINUTE);
    } // getMinute

    private static int calendarMonthToInt(int calendarMonth) {
        if (calendarMonth == Calendar.JANUARY) {
            return 1;
        } else if (calendarMonth == Calendar.FEBRUARY) {
            return 2;
        } else if (calendarMonth == Calendar.MARCH) {
            return 3;
        } else if (calendarMonth == Calendar.APRIL) {
            return 4;
        } else if (calendarMonth == Calendar.MAY) {
            return 5;
        } else if (calendarMonth == Calendar.JUNE) {
            return 6;
        } else if (calendarMonth == Calendar.JULY) {
            return 7;
        } else if (calendarMonth == Calendar.AUGUST) {
            return 8;
        } else if (calendarMonth == Calendar.SEPTEMBER) {
            return 9;
        } else if (calendarMonth == Calendar.OCTOBER) {
            return 10;
        } else if (calendarMonth == Calendar.NOVEMBER) {
            return 11;
        } else if (calendarMonth == Calendar.DECEMBER) {
            return 12;
        } else {
            return 1;
        }
    } // calendarMonthToInt

    public static String format(
        Date date,
        String pattern) {
        // returns a String representation of the date argument,
        // formatted according to the pattern argument, which
        // has the same syntax as the argument of the SimpleDateFormat
        // class
        SimpleDateFormat formatter = new SimpleDateFormat(pattern);

        return formatter.format(date);
    } // format

    public static String format(
        Calendar cal,
        String pattern) {
        SimpleDateFormat formatter = new SimpleDateFormat(pattern);

        return formatter.format(calendarToDate(cal));
    } // format

    private static int intToCalendarMonth(int month) {
        if (month == 1) {
            return Calendar.JANUARY;
        } else if (month == 2) {
            return Calendar.FEBRUARY;
        } else if (month == 3) {
            return Calendar.MARCH;
        } else if (month == 4) {
            return Calendar.APRIL;
        } else if (month == 5) {
            return Calendar.MAY;
        } else if (month == 6) {
            return Calendar.JUNE;
        } else if (month == 7) {
            return Calendar.JULY;
        } else if (month == 8) {
            return Calendar.AUGUST;
        } else if (month == 9) {
            return Calendar.SEPTEMBER;
        } else if (month == 10) {
            return Calendar.OCTOBER;
        } else if (month == 11) {
            return Calendar.NOVEMBER;
        } else if (month == 12) {
            return Calendar.DECEMBER;
        } else {
            return Calendar.JANUARY;
        }
    } // intToCalendarMonth

    public static Calendar dateToCalendar(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);

        return cal;
    } // dateToCalendar

    public static Date calendarToDate(Calendar cal) {
        return cal.getTime();
    } // calendarToDate
} // class