显示当前月份的日期信息

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package com.test;

import java.text.DateFormatSymbols;
import java.util.Calendar;
import java.util.GregorianCalendar;

public class CalendarTest {
public static void main(String[] args) {
  GregorianCalendar d = new GregorianCalendar();

  //得到当前的日期，如：2月14日
  int today = d.get(Calendar.DAY_OF_MONTH); //14
  int month = d.get(Calendar.MONTH); //从0开始的,1+1=2 .2月14日

  d.set(Calendar.DAY_OF_MONTH, 1);
  int weekday = d.get(Calendar.DAY_OF_WEEK); //4

  //表示每个星期从星期几开始（中国-1，美国-7）
  int firstDayOfWeek = d.getFirstDayOfWeek();

  //indent的作用是用来对日历的第一行进行缩进的
  //取得的weekday值比实际大1
  int indent = 0;
  while(weekday != firstDayOfWeek) {
   indent++;
   d.add(Calendar.DAY_OF_MONTH, -1);
   weekday = d.get(Calendar.DAY_OF_WEEK);
  }

  String[] weekdayNames = new DateFormatSymbols().getShortWeekdays();
  do {
   System.out.printf("%4s\t", 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("\t");
  }

  d.set(Calendar.DAY_OF_MONTH, 1);
  do {
   int day = d.get(Calendar.DAY_OF_MONTH);
   System.out.printf("%3d", day);

   if(day == today) {
    System.out.print("*");
   } else {
    System.out.print(" ");
   }
   System.out.print("\t");

   d.add(Calendar.DAY_OF_MONTH, 1);
   weekday = d.get(Calendar.DAY_OF_WEEK);
   if(weekday == firstDayOfWeek) {
    System.out.println();
   }
  } while(d.get(Calendar.MONTH) == month);

  if(weekday != firstDayOfWeek) {
   System.out.println();
  }
}
}