public abstract class Calendar extends Objectimplements Serializable, Cloneable, Comparable

Calendar rightNow = Calendar.getInstance();

/**
 * Gets a calendar using the default time zone and locale. The
 * Calendar returned is based on the current time
 * in the default time zone with the default locale.
 *
 * @return a Calendar.
 */
public static Calendar getInstance()
{
  Calendar cal = createCalendar(TimeZone.getDefaultRef(), Locale.getDefault(Locale.Category.FORMAT));
  cal.sharedZone = true;
  return cal;
}

private static Calendar createCalendar(TimeZone zone,
                      Locale aLocale)
  {
    Calendar cal = null;

    String caltype = aLocale.getUnicodeLocaleType("ca");
    if (caltype == null) {
      // Calendar type is not specified.
      // If the specified locale is a Thai locale,
      // returns a BuddhistCalendar instance.
      if ("th".equals(aLocale.getLanguage())
          && ("TH".equals(aLocale.getCountry()))) {
        cal = new BuddhistCalendar(zone, aLocale);
      } else {
        cal = new GregorianCalendar(zone, aLocale);
      }
    } else if (caltype.equals("japanese")) {
      cal = new JapaneseImperialCalendar(zone, aLocale);
    } else if (caltype.equals("buddhist")) {
      cal = new BuddhistCalendar(zone, aLocale);
    } else {
      // Unsupported calendar type.
      // Use Gregorian calendar as a fallback.
      cal = new GregorianCalendar(zone, aLocale);
    }

    return cal;
  }

package com.test.calendar;

import java.util.Calendar;

import org.junit.Before;
import org.junit.Test;

public class CalendarDemo {
  Calendar calendar = null;

  @Before
  public void test() {
    calendar = Calendar.getInstance();
  }

  // 基本用法，获取年月日时分秒星期
  @Test
  public void test1() {
    // 获取年
    int year = calendar.get(Calendar.YEAR);

    // 获取月，这里需要需要月份的范围为0~11，因此获取月份的时候需要+1才是当前月份值
    int month = calendar.get(Calendar.MONTH) + 1;

    // 获取日
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    // 获取时
    int hour = calendar.get(Calendar.HOUR);
    // int hour = calendar.get(Calendar.HOUR_OF_DAY); // 24小时表示

    // 获取分
    int minute = calendar.get(Calendar.MINUTE);

    // 获取秒
    int second = calendar.get(Calendar.SECOND);

    // 星期，英语国家星期从星期日开始计算
    int weekday = calendar.get(Calendar.DAY_OF_WEEK);

    System.out.println("现在是" + year + "年" + month + "月" + day + "日" + hour
        + "时" + minute + "分" + second + "秒" + "星期" + weekday);
  }

  // 一年后的今天
  @Test
  public void test2() {
    // 同理换成下个月的今天calendar.add(Calendar.MONTH, 1);
    calendar.add(Calendar.YEAR, 1);

    // 获取年
    int year = calendar.get(Calendar.YEAR);

    // 获取月
    int month = calendar.get(Calendar.MONTH) + 1;

    // 获取日
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    System.out.println("一年后的今天：" + year + "年" + month + "月" + day + "日");
  }

  // 获取任意一个月的最后一天
  @Test
  public void test3() {
    // 假设求6月的最后一天
    int currentMonth = 6;
    // 先求出7月份的第一天，实际中这里6为外部传递进来的currentMonth变量
    // 1
    calendar.set(calendar.get(Calendar.YEAR), currentMonth, 1);

    calendar.add(Calendar.DATE, -1);

    // 获取日
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    System.out.println("6月份的最后一天为" + day + "号");
  }

  // 设置日期
  @Test
  public void test4() {
    calendar.set(Calendar.YEAR, 2000);
    System.out.println("现在是" + calendar.get(Calendar.YEAR) + "年");

    calendar.set(2008, 8, 8);
    // 获取年
    int year = calendar.get(Calendar.YEAR);

    // 获取月
    int month = calendar.get(Calendar.MONTH);

    // 获取日
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    System.out.println("现在是" + year + "年" + month + "月" + day + "日");
  }
}