Java日期操作常用方法

/**
     * 取得指定月份的第一天
     *
     * @param strdate String
     * @return String
     */
    public String getMonthBegin(String strdate)
    {
        java.util.Date date = parseFormatDate(strdate);
        return formatDateByFormat(date,"yyyy-MM") + "-01";
    }

    /**
     * 取得指定月份的最后一天
     *
     * @param strdate String
     * @return String
     */
    public String getMonthEnd(String strdate)
    {
        java.util.Date date = parseFormatDate(getMonthBegin(strdate));
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.MONTH,1);
        calendar.add(Calendar.DAY_OF_YEAR, -1);
        return formatDate(calendar.getTime());
    }

    /**
     * 常用的格式化日期
     *
     * @param date Date
     * @return String
     */
    public String formatDate(java.util.Date date)
    {
        return formatDateByFormat(date,"yyyy-MM-dd");
    }

    /**
     * 以指定的格式来格式化日期
     *
     * @param date Date
     * @param format String
     * @return String
     */
    public String formatDateByFormat(java.util.Date date,String format)
    {
        String result = "";
        if(date != null)
        {
            try
            {
                SimpleDateFormat sdf = new SimpleDateFormat(format);
                result = sdf.format(date);
            }
            catch(Exception ex)
            {
                LOGGER.info("date:" + date);
                ex.printStackTrace();
            }
        }
        return result;
    }



/**
 * 日期操作
 *
 * @author xxx
 * @version 2.0 jdk1.4.0 tomcat5.1.0 * Updated Date:2005/03/10
 */
public class DateUtil {
 /**
  * 格式化日期
  *
  * @param dateStr
  *            字符型日期
  * @param format
  *            格式
  * @return 返回日期
  */
 public static java.util.Date parseDate(String dateStr, String format) {
  java.util.Date date = null;
  try {
   java.text.DateFormat df = new java.text.SimpleDateFormat(format);
   String dt=Normal.parse(dateStr).replaceAll(
     "-", "/");
   if((!dt.equals(""))&&(dt.length()
    dt+=format.substring(dt.length()).replaceAll("[YyMmDdHhSs]","0");
   }
   date = (java.util.Date) df.parse(dt);
  } catch (Exception e) {
  }
  return date;
 }

 public static java.util.Date parseDate(String dateStr) {
  return parseDate(dateStr, "yyyy/MM/dd");
 }

 public static java.util.Date parseDate(java.sql.Date date) {
  return date;
 }

 public static java.sql.Date parseSqlDate(java.util.Date date) {
  if (date != null)
   return new java.sql.Date(date.getTime());
  else
   return null;
 }

 public static java.sql.Date parseSqlDate(String dateStr, String format) {
  java.util.Date date = parseDate(dateStr, format);
  return parseSqlDate(date);
 }

 public static java.sql.Date parseSqlDate(String dateStr) {
  return parseSqlDate(dateStr, "yyyy/MM/dd");
 }


 public static java.sql.Timestamp parseTimestamp(String dateStr,
   String format) {
  java.util.Date date = parseDate(dateStr, format);
  if (date != null) {
   long t = date.getTime();
   return new java.sql.Timestamp(t);
  } else
   return null;
 }

 public static java.sql.Timestamp parseTimestamp(String dateStr) {
  return parseTimestamp(dateStr, "yyyy/MM/dd HH:mm:ss");
 }

 /**
  * 格式化输出日期
  *
  * @param date
  *            日期
  * @param format
  *            格式
  * @return 返回字符型日期
  */
 public static String format(java.util.Date date, String format) {
  String result = "";
  try {
   if (date != null) {
    java.text.DateFormat df = new java.text.SimpleDateFormat(format);
    result = df.format(date);
   }
  } catch (Exception e) {
  }
  return result;
 }

 public static String format(java.util.Date date) {
  return format(date, "yyyy/MM/dd");
 }

 /**
  * 返回年份
  *
  * @param date
  *            日期
  * @return 返回年份
  */
 public static int getYear(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.YEAR);
 }

 /**
  * 返回月份
  *
  * @param date
  *            日期
  * @return 返回月份
  */
 public static int getMonth(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.MONTH) + 1;
 }

 /**
  * 返回日份
  *
  * @param date
  *            日期
  * @return 返回日份
  */
 public static int getDay(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.DAY_OF_MONTH);
 }

 /**
  * 返回小时
  *
  * @param date
  *            日期
  * @return 返回小时
  */
 public static int getHour(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.HOUR_OF_DAY);
 }

 /**
  * 返回分钟
  *
  * @param date
  *            日期
  * @return 返回分钟
  */
 public static int getMinute(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.MINUTE);
 }

 /**
  * 返回秒钟
  *
  * @param date
  *            日期
  * @return 返回秒钟
  */
 public static int getSecond(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.get(java.util.Calendar.SECOND);
 }

 /**
  * 返回毫秒
  *
  * @param date
  *            日期
  * @return 返回毫秒
  */
 public static long getMillis(java.util.Date date) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTime(date);
  return c.getTimeInMillis();
 }

 /**
  * 返回字符型日期
  *
  * @param date
  *            日期
  * @return 返回字符型日期
  */
 public static String getDate(java.util.Date date) {
  return format(date, "yyyy/MM/dd");
 }

 /**
  * 返回字符型时间
  *
  * @param date
  *            日期
  * @return 返回字符型时间
  */
 public static String getTime(java.util.Date date) {
  return format(date, "HH:mm:ss");
 }

 /**
  * 返回字符型日期时间
  *
  * @param date
  *            日期
  * @return 返回字符型日期时间
  */
 public static String getDateTime(java.util.Date date) {
  return format(date, "yyyy/MM/dd HH:mm:ss");
 }

 /**
  * 日期相加
  *
  * @param date
  *            日期
  * @param day
  *            天数
  * @return 返回相加后的日期
  */
 public static java.util.Date addDate(java.util.Date date, int day) {
  java.util.Calendar c = java.util.Calendar.getInstance();
  c.setTimeInMillis(getMillis(date) + ((long) day) * 24 * 3600 * 1000);
  return c.getTime();
 }

 /**
  * 日期相减
  *
  * @param date
  *            日期
  * @param date1
  *            日期
  * @return 返回相减后的日期
  */
 public static int diffDate(java.util.Date date, java.util.Date date1) {
  return (int) ((getMillis(date) - getMillis(date1)) / (24 * 3600 * 1000));
 }
}



Calendar now = Calendar.getInstance();
int year = now.get(Calendar.YEAR);
int date = now.get(Calendar.DAY_OF_MONTH);
int month = now.get(Calendar.MONTH) + 1;
int hour = now.get(Calendar.HOUR);
int min = now.get(Calendar.MINUTE);
int sec = now.get(Calendar.SECOND);




import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.*;
/**
 *
 *
public class ManageWeek {
 //判断两个日期是否在同一周
 boolean isSameWeekDates(Date date1, Date date2) {
  Calendar cal1 = Calendar.getInstance();
  Calendar cal2 = Calendar.getInstance();
  cal1.setTime(date1);
  cal2.setTime(date2);
  int subYear = cal1.get(Calendar.YEAR) - cal2.get(Calendar.YEAR);
  if (0 == subYear) {
    if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))
   return true;
  }
  else if (1 == subYear && 11 == cal2.get(Calendar.MONTH)) {
    // 如果12月的最后一周横跨来年第一周的话则最后一周即算做来年的第一周
    if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))
   return true;
  }
  else if (-1 == subYear && 11 == cal1.get(Calendar.MONTH)) {
    if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))
   return true;
  }
  return false;
 }


 //产生周序列
 public static String  getSeqWeek(){
  Calendar c = Calendar.getInstance(Locale.CHINA);
  String week = Integer.toString(c.get(Calendar.WEEK_OF_YEAR));
  if(week.length()==1)week = "0" + week;
  String year = Integer.toString(c.get(Calendar.YEAR));
  return year+week;

 }

  //获得周一的日期
  public static String getMonday(Date date){
   Calendar c = Calendar.getInstance();
   c.setTime(date);
   c.set(Calendar.DAY_OF_WEEK,Calendar.MONDAY);
   return new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());
  }


  //获得周五的日期
  public static String getFriday(Date date){
   Calendar c = Calendar.getInstance();
   c.setTime(date);
   c.set(Calendar.DAY_OF_WEEK,Calendar.FRIDAY);
   return new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());


  }

  public static void main(String[] args){

  }

}