学习Java的Date、Calendar日期操作

本文介绍了java开发过程中日期相关操作，分享的代码如下：

package jse;
 
import java.io.unsupportedencodingexception;
import java.text.parseexception;
import java.text.simpledateformat;
import java.util.calendar;
import java.util.date;
import java.util.locale;
 
/**
 * 常用日期操作
 * 
 * @author puck
 * createdate 2015-07-30 22:54:38
 */
public class testdate
{
  public static void main(string[] args) throws parseexception, unsupportedencodingexception
  {
    calendar cal = calendar.getinstance();
//   cal.add(calendar.day_of_month, -48);
    system.out.println(datetostring(cal));
  }
   
  /**
   * 日期格式化
   * @param date
   * @return
   */
  public static string datetostring(date date)
  {
//   simpledateformat format = new simpledateformat("y年mm月dd日 e hh时mm分ss秒", locale.china);
//   simpledateformat format = new simpledateformat("y年m月d日 e h时m分s秒", locale.china);
    simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss", locale.china); // example
    return sdf.format(date);
  }
   
  /**
   * 日期格式化
   * @param date
   * @return
   */
  public static string datetostring(calendar cal)
  {
    return datetostring(cal.gettime());
  }
 
  /**
   * datestring 转 calendar
   * 
   * @param date
   *      format:2015-06-16 date
   * @return calendar
   * @throws parseexception
   */
  public static calendar datestringtocalendar(string datestr) throws parseexception
  {
//   calendar cal = calendar.getinstance();
//   cal.clear();
//   cal.set(integer.parseint(date.substring(0, 4)), integer.parseint(date.substring(5, 7)) - 1,
//       integer.parseint(date.substring(8, 10)));
//   return cal;
     
    simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
    date date = sdf.parse(datestr);
    calendar cal = calendar.getinstance();
    cal.settime(date);
    return cal;
  }
 
  /**
   * datestring 转 date
   * 
   * @param date
   *      format:yyyy-mm-dd hh:mm:ss date
   * @return calendar
   * @throws parseexception
   */
  public static date datestringtodate(string date) throws parseexception
  {
    simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
    return sdf.parse(date);
  }
 
  /**
   * date convert to calendar
   * 
   * @param date
   * @return
   */
  public static calendar datetocalendar(date date)
  {
    calendar c1 = calendar.getinstance();
    c1.settime(date);
    return c1;
  }
 
  /**
   * calendar convert to date
   * @param cal
   * @return
   */
  public static date calendartodate(calendar cal)
  {
    return cal.gettime();
  }
 
  /**
   * 计算两个日期相差年月日
   * 
   * @param date
   *      c1
   * @param date
   *      c2
   * @return int[]{year, month, day}
   */
  public int[] calculatedifferday(date d1, date d2)
  {
    calendar c1 = calendar.getinstance();
    c1.settime(d1);
    calendar c2 = calendar.getinstance();
    c1.settime(d2);
    return calculatedifferday(c1, c2);
  }
 
  /**
   * 计算两个日期相差年月日
   * 
   * @param calendar
   *      c1
   * @param calendar
   *      c2
   * @return int[]{year, month, day}
   */
  public int[] calculatedifferday(calendar c1, calendar c2)
  {
    int[] p1 = { c1.get(calendar.year), c1.get(calendar.month), c1.get(calendar.day_of_month) };
    int[] p2 = { c2.get(calendar.year), c2.get(calendar.month), c2.get(calendar.day_of_month) };
    system.out.println("p1[0]=" + p1[0] + " p1[1]=" + p1[1] + " p1[2]=" + p1[2]);
    system.out.println("p2[0]=" + p2[0] + " p2[1]=" + p2[1] + " p2[2]=" + p2[2]);
    int year = p2[0] - p1[0];
    int month = (p2[0] * 12) + p2[1] - ((p1[0] * 12) + p1[1]);
    int day = (int) ((c2.gettimeinmillis() - c1.gettimeinmillis()) / (24 * 60 * 60 * 1000));
    return new int[] { year, month, day };
  }
 
  /**
   * 获取日期所在周的第一天
   * 
   * @param c
   * @return
   */
  public static calendar getlastdayofweek(calendar c)
  {
//   simpledateformat format2 = new simpledateformat("y年m月d日 e h时m分s秒", locale.china);
//   system.out.println("当前时间:" + format2.format(c.gettime()));
    c.set(calendar.day_of_week, calendar.monday);
//   system.out.println("周一时间:" + format2.format(c.gettime()));
    return c;
  }
 
  /**
   * 日期加减
   * @param c
   * @param day
   * @return
   */
  public static calendar addordecreaseday(calendar c, int day)
  {
    c.add(calendar.day_of_month, day);
    return c;
  }
 
  /**
   * 获取月最后一天
   * @param year
   * @param month
   * @return
   */
  public static int getlastdayofmonth(int year, int month)
  {
    calendar c = calendar.getinstance();
    c.set(year, month - 1, 1);
    return c.getactualmaximum(calendar.day_of_month);
  }
   
  /**
   * 获取月最后一天
   * @param cal
   * @return
   */
  public static int getlastdayofmonth(calendar cal)
  {
    return cal.getactualmaximum(calendar.day_of_month);
  }
   
}