学习Java的Date、Calendar日期操作

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);  }   }