import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class DateTestUtil {  public static void main(String[] args) throws Exception {    SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMdd");  String str="20110823";  Date dt=sdf.parse(str);  Calendar rightNow = Calendar.getInstance();  rightNow.setTime(dt);  rightNow.add(Calendar.YEAR,-1);//日期減1年  rightNow.add(Calendar.MONTH,3);//日期加3個月  rightNow.add(Calendar.DAY_OF_YEAR,10);//日期加10天  Date dt1=rightNow.getTime();  String reStr = sdf.format(dt1);  System.out.println(reStr); }}

import java.text.SimpleDateFormat; import java.util.Date;  public class DateTest {      public static void main(String[] arg){     Date now = new Date();             addAndSubtractDaysByGetTime(now,-5);     addAndSubtractDaysByGetTime(now,5);     addAndSubtractDaysByCalendar(now,-5);     addAndSubtractDaysByCalendar(now,5);   }       public static Date addAndSubtractDaysByGetTime(Date dateTime/*待處理的日期*/,int n/*加減天數*/){            //日期格式      SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");       SimpleDateFormat dd=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");                System.out.println(df.format(new Date(dateTime.getTime() + n * 24 * 60 * 60 * 1000L)));      //System.out.println(dd.format(new Date(dateTime.getTime() + n * 24 * 60 * 60 * 1000L)));      //注意這里一定要轉換成Long類型，要不n超過25時會出現范圍溢出，從而得不到想要的日期值      return new Date(dateTime.getTime() + n * 24 * 60 * 60 * 1000L);    }        public static Date addAndSubtractDaysByCalendar(Date dateTime/*待處理的日期*/,int n/*加減天數*/){            //日期格式      SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");       SimpleDateFormat dd=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");             java.util.Calendar calstart = java.util.Calendar.getInstance();        calstart.setTime(dateTime);       calstart.add(java.util.Calendar.DAY_OF_WEEK, n);             System.out.println(df.format(calstart.getTime()));      //System.out.println(dd.format(calstart.getTime()));      return calstart.getTime();    }  }

package com.data.utils;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class DateFormat { /**  * 日期減幾年  */ public static String dateMinusYear(String str) throws Exception {  SimpleDateFormat sdf = new SimpleDateFormat("yyyyMM");  Date dt = sdf.parse(str);  Calendar rightNow = Calendar.getInstance();  rightNow.setTime(dt);  rightNow.add(Calendar.YEAR, -1);// 日期減1年  Date dt1 = rightNow.getTime();  String reStr = sdf.format(dt1);  return reStr; } /**  * 日期加幾年  */ public static String dateAddYear(String str) throws Exception {  SimpleDateFormat sdf = new SimpleDateFormat("yyyyMM");  Date dt = sdf.parse(str);  Calendar rightNow = Calendar.getInstance();  rightNow.setTime(dt);  rightNow.add(Calendar.YEAR, 1);// 日期加1年  Date dt1 = rightNow.getTime();  String reStr = sdf.format(dt1);  return reStr; } /**  * 日期減幾月  */ public static String dateMinusMonth(String str) throws Exception {  SimpleDateFormat sdf = new SimpleDateFormat("yyyyMM");  Date dt = sdf.parse(str);//將字符串生成Date  Calendar rightNow = Calendar.getInstance();  rightNow.setTime(dt);//使用給定的 Date 設置此 Calendar 的時間。   rightNow.add(Calendar.MONTH, -1);// 日期減1個月  Date dt1 = rightNow.getTime();//返回一個表示此 Calendar 時間值的 Date 對象。  String reStr = sdf.format(dt1);//將給定的 Date 格式化為日期/時間字符串，并將結果添加到給定的 StringBuffer。  return reStr; } /**  * 日期加幾月  */ public static String dateAddMonth(String str) throws Exception {  SimpleDateFormat sdf = new SimpleDateFormat("yyyyMM");  Date dt = sdf.parse(str);  Calendar rightNow = Calendar.getInstance();  rightNow.setTime(dt);  rightNow.add(Calendar.MONTH, 1);// 日期加3個月  // rightNow.add(Calendar.DAY_OF_YEAR,10);//日期加10天  Date dt1 = rightNow.getTime();  String reStr = sdf.format(dt1);  return reStr; } /**  * 獲取當前年月的第一個月的str  * @param str  *   201505  * @return 201501  * @throws Exception  */ public static String dateOneMonth(String str) {  str = str.substring(0, str.length() - 2);  str = str + "01";  return str; } /**  * 算出所選月份距離一月份有幾個月。  * @param str 201509  * @return 9  */ public static int dateDistanceMonth(String str) {  int i = Integer.parseInt(str);  int j = Integer.parseInt(DateFormat.dateOneMonth(str));  System.out.println(i - j);  return i - j + 1; } /**  * 獲取兩個時間的時間差，精確到毫秒  * @param str  * @return  */ public static String TimeDifference(long start, long end) {  long between = end - start;  long day = between / (24 * 60 * 60 * 1000);  long hour = (between / (60 * 60 * 1000) - day * 24);  long min = ((between / (60 * 1000)) - day * 24 * 60 - hour * 60);  long s = (between / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);  long ms = (between - day * 24 * 60 * 60 * 1000 - hour * 60 * 60 * 1000    - min * 60 * 1000 - s * 1000);  String timeDifference = day + "天" + hour + "小時" + min + "分" + s + "秒" + ms    + "毫秒";  return timeDifference; }} /**  * 獲取24小時、一周、一個月的起始時間  *   * @param timeInterval  *   : DAY_TIME_INTERVAL WEEK_TIME_INTERVAL MONTH_TIME_INTERVAL  * @return "yyyy-mm-dd hh:mm:ss"  */ public static String getStartTime(int timeInterval) {  Calendar cal = Calendar.getInstance();  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  if (DAY_TIME_INTERVAL == timeInterval) {// 獲取24小時的起始時間   cal.set(Calendar.HOUR_OF_DAY, 0);   cal.set(Calendar.MINUTE, 0);   cal.set(Calendar.SECOND, 0);   String startTime = sdf.format(cal.getTime());   return startTime;  } else if (WEEK_TIME_INTERVAL == timeInterval) {   int weekday = cal.get(Calendar.DAY_OF_WEEK) - 1;   cal.add(Calendar.DATE, -weekday);   cal.set(Calendar.HOUR_OF_DAY, 0);   cal.set(Calendar.MINUTE, 0);   cal.set(Calendar.SECOND, 0);   String startTime = sdf.format(cal.getTime());   return startTime;  } else if (MONTH_TIME_INTERVAL == timeInterval) {   int dayofmonthMin = cal.getActualMinimum(Calendar.DAY_OF_MONTH);   // c.add(Calendar.DATE, -dayofmonth);   cal.set(Calendar.DATE, dayofmonthMin);   cal.set(Calendar.HOUR_OF_DAY, 0);   cal.set(Calendar.MINUTE, 0);   cal.set(Calendar.SECOND, 0);   String startTime = sdf.format(cal.getTime());   return startTime;  }  return null; } /**  * 獲取24小時、一周、一個月的結束時間  *   * @param timeInterval  *   : DAY_TIME_INTERVAL WEEK_TIME_INTERVAL MONTH_TIME_INTERVAL  * @return "yyyy-mm-dd hh:mm:ss"  */ public static String getEndTime(int timeInterval) {  Calendar cal = Calendar.getInstance();  cal.setTimeZone(TimeZone.getTimeZone("GMT+8"));  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  if (DAY_TIME_INTERVAL == timeInterval) {   cal.set(Calendar.HOUR_OF_DAY, 23);   cal.set(12, 59);   cal.set(13, 59);   long date = cal.getTimeInMillis();   String endTime = sdf.format(new Date(date));   return endTime;  } else if (WEEK_TIME_INTERVAL == timeInterval) {   int weekday = cal.get(Calendar.DAY_OF_WEEK) - 1;   cal.add(Calendar.DATE, -weekday);   cal.add(Calendar.DATE, 6);   cal.set(Calendar.HOUR_OF_DAY, 23);   cal.set(12, 59);   cal.set(13, 59);   long date = cal.getTimeInMillis();   String endTime = sdf.format(new Date(date));   return endTime;  } else if (MONTH_TIME_INTERVAL == timeInterval) {   int dayOfMonthMax = cal.getActualMaximum(Calendar.DAY_OF_MONTH);   cal.set(Calendar.DATE, dayOfMonthMax);   cal.set(Calendar.HOUR_OF_DAY, 23);   cal.set(Calendar.MINUTE, 59);   cal.set(Calendar.SECOND, 59);   String endTime = sdf.format(cal.getTime());   return endTime;  }  return null; } /**  * 判斷dateStr是否在start和end中間，start和end都可以為null yyyyMMddHHmmss或者yyyyMMdd格式  *   * @author you.xu  * @date 2015年8月19日下午3:11:46  * @param dateStr  * @param start  * @param end  * @return  */ public static boolean checkDateVal(String dateStr, String start, String end) {  boolean isDateRight = false;  Date date = null;  Date startDate = null;  Date endDate = null;  SimpleDateFormat sdf = null;  // 判斷日期格式  if (14 == dateStr.length()) {   sdf = new SimpleDateFormat("yyyyMMddHHmmss");  } else if (8 == dateStr.length()) {   sdf = new SimpleDateFormat("yyyyMMdd");  } else   return false;  try {   // 更改判斷日期格式   date = sdf.parse(dateStr);  } catch (ParseException e) {   log.error(e, e);  }  if ((start == null) && (end != null)) {   try {    endDate = sdf.parse(end);   } catch (ParseException ex1) {    log.error(ex1, ex1);   }   if ((date != null) && (endDate != null))// Check parameters for   {    if (date.compareTo(endDate) <= 0)     isDateRight = true;   }  } else if ((start != null) && (end == null)) {   try {    startDate = sdf.parse(start);   } catch (ParseException ex1) {    log.error(ex1, ex1);   }   if ((date != null) && (startDate != null)) {    if (date.compareTo(startDate) >= 0)     isDateRight = true;   }  } else if ((start != null) && (end != null)) {   try {    startDate = sdf.parse(start);    endDate = sdf.parse(end);   } catch (ParseException ex2) {    System.out.println(ex2.toString());   }   if ((startDate != null) && (date != null) && (endDate != null)) {    if ((date.compareTo(startDate) >= 0)      && (date.compareTo(endDate) <= 0))     isDateRight = true;   }  }  return isDateRight; } /**  * 判斷dateStr是否在start和end中間，start和end都可以為null long形格式  *   * @author you.xu  * @date 2015年8月19日下午3:12:35  * @param dateStr  * @param start  * @param end  * @return  */ public static boolean checkDateV(String dateStr, String start, String end) {  boolean isDateRight = false;  long date = -1;  long fromDate = -1;  long toDate = -1;  date = java.lang.Long.parseLong(dateStr);  if ((start == null) && (end == null)) {   isDateRight = true;  } else if ((start == null) && (end != null)) {   try {    toDate = java.lang.Long.parseLong(end);   } catch (NumberFormatException nfe) {    log.error(nfe, nfe);   }   if (date <= toDate) {    isDateRight = true;   }  } else if ((start != null) && (end == null)) {   try {    fromDate = java.lang.Long.parseLong(start);   } catch (NumberFormatException nfe) {    log.error(nfe, nfe);   }   if (date >= fromDate) {    isDateRight = true;   }  } else if ((start != null) && (end != null)) {   try {    toDate = java.lang.Long.parseLong(end);    fromDate = java.lang.Long.parseLong(start);   } catch (NumberFormatException nfe) {    log.error(nfe, nfe);   }   if ((date <= toDate) && (date >= fromDate)) {    isDateRight = true;   }  }  return isDateRight; }