org.apache.commons.lang.DateUtils

static java.util.Date
 addDays (java.util.Date date, int amount)
          Adds a number of days to a date returning a new object.

一个日期对象＋ n天
 
static java.util.Date
 addHours (java.util.Date date, int amount)
          Adds a number of hours to a date returning a new object.

一个日期对象＋ n小时
 
static java.util.Date
 addMilliseconds (java.util.Date date, int amount)
          Adds a number of milliseconds to a date returning a new object.

一个日期对象 +n毫秒
 
static java.util.Date
 addMinutes (java.util.Date date, int amount)
          Adds a number of minutes to a date returning a new object.

一个日期对象 +n分
 
static java.util.Date
 addMonths (java.util.Date date, int amount)
          Adds a number of months to a date returning a new object.

 一个日期对象＋ n月
 
static java.util.Date
 addSeconds (java.util.Date date, int amount)
          Adds a number of seconds to a date returning a new object.

一个日期对象＋ n秒
 
static java.util.Date
 addWeeks (java.util.Date date, int amount)
          Adds a number of weeks to a date returning a new object.

一个日期对象＋ N个星期
 
static java.util.Date
 addYears (java.util.Date date, int amount)
          Adds a number of years to a date returning a new object.

一个日期对象＋ N年
 
 
 
static boolean
 isSameDay (java.util.Date date1, java.util.Date date2)
          Checks if two date objects are on the same day ignoring time.

两个日期对象是否相等（只比较年－月－日）
 
 
 
static boolean
 isSameInstant (java.util.Date date1, java.util.Date date2)
          Checks if two date objects represent the same instant in time.

比较两个日期是否完全相等（精确到毫秒）
 
 
 
static java.util.Date
 parseDate (java.lang.String str, java.lang.String[] parsePatterns)
          Parses a string representing a date by trying a variety of different parsers.

例 ：

String[] format={ "yyyy-MM-dd" };

System. out .println(DateUtils.parseDate ( "2009-10-20" , format));