java简单日历

import java.text.DateFormatSymbols;
import java.util.*;

/**
* @version 1.4 2007-04-07
* @author Cay Horstmann
*/

public class CalendarTest
{
public static void main(String[] args)
{
// construct d as current date
GregorianCalendar d = new GregorianCalendar();

int today = d.get(Calendar.DAY_OF_MONTH);
int month = d.get(Calendar.MONTH);

// set d to start date of the month
d.set(Calendar.DAY_OF_MONTH, 1);

int weekday = d.get(Calendar.DAY_OF_WEEK);

// get first day of week (Sunday in the U.S.)
int firstDayOfWeek = d.getFirstDayOfWeek();

// determine the required indentation for the first line
int indent = 0;
while (weekday != firstDayOfWeek)
{
indent++;
d.add(Calendar.DAY_OF_MONTH, -1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}

// print weekday names
String[] weekdayNames = new DateFormatSymbols().getShortWeekdays();
do
{
System.out.printf("%4s", weekdayNames[weekday]);
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}
while (weekday != firstDayOfWeek);
System.out.println();

for (int i = 1; i <= indent; i++)
System.out.print("      ");

d.set(Calendar.DAY_OF_MONTH, 1);
do
{
// print day
int day = d.get(Calendar.DAY_OF_MONTH);
System.out.printf("%5d", day);

// mark current day with *
if (day == today) System.out.print("*");
else System.out.print(" ");

// advance d to the next day
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK);

// start a new line at the start of the week
if (weekday == firstDayOfWeek) System.out.println();
}
while (d.get(Calendar.MONTH) == month);
// the loop exits when d is day 1 of the next month

// print final end of line if necessary
if (weekday != firstDayOfWeek) System.out.println();
}
}

run:
星期日 星期一 星期二 星期三 星期四 星期五 星期六
1     2*    3     4     5     6     7
8     9    10    11    12    13    14
15    16    17    18    19    20    21
22    23    24    25    26    27    28
29    30
成功生成（总时间：1 秒）