web开发中公用组件的开发之一---------DateUtils

转http://www.iteye.com/topic/432172

在web应用中我们经常要到用到对日期的操作
已经有很多的开源代码供选择，例如apache 就有
不是太复杂就是不太适合中国国情的，反正项目中很少用到apache的公用组件包

下面是我在web开发中常用的些方法操作
现简单列举出来，已示记念。

 package  com.chinadim.test.utils;

 import  java.text.ParsePosition;
 import  java.text.SimpleDateFormat;
 import  java.util.Calendar;
 import  java.util.Date;


 /**
  * xxxxx
  * xxxxxx
  */
 public   class  DateUtils {

     /**
      * 静 态常量
      */
     public   static   final  String C_TIME_PATTON_DEFAULT =  "yyyy-MM-dd HH:mm:ss" ;
     public   static   final  String C_DATE_PATTON_DEFAULT =  "yyyy-MM-dd" ;

     public   static   final   int  C_ONE_SECOND =  1000 ;
     public   static   final   int  C_ONE_MINUTE =  60  * C_ONE_SECOND;
     public   static   final   long  C_ONE_HOUR =  60  * C_ONE_MINUTE;
     public   static   final   long  C_ONE_DAY =  24  * C_ONE_HOUR;

     /**
      * 计 算当前月份的最大天数
      * @return
      */
     public   static   int  findMaxDayInMonth() {
         return  findMaxDayInMonth( 0 ,  0 );
     }

     /**
      * 计 算指定日期月份的最大天数
      * @param date
      * @return
      */
     public   static   int  findMaxDayInMonth(Date date) {
         if  (date ==  null ) {
             return   0 ;
         }
         return  findMaxDayInMonth(date2Calendar(date));
     }

     /**
      * 计 算指定日历月份的最大天数
      * @param calendar
      * @return
      */
     public   static   int  findMaxDayInMonth(Calendar calendar) {
         if  (calendar ==  null ) {
             return   0 ;
         }

         return  calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
     }

     /**
      * 计 算当前年某月份的最大天数
      * @param month
      * @return
      */
     public   static   int  findMaxDayInMonth( int  month) {
         return  findMaxDayInMonth( 0 , month);
     }

     /**
      * 计 算某年某月份的最大天数
      * @param year
      * @param month
      * @return
      */
     public   static   int  findMaxDayInMonth( int  year,  int  month) {
         Calendar calendar = Calendar.getInstance();
         if  (year >  0 ) {
             calendar.set(Calendar.YEAR, year);
         }

         if  (month >  0 ) {
             calendar.set(Calendar.MONTH, month - 1 );
         }

         return  findMaxDayInMonth(calendar);
     }

     /**
      * Calendar 转 换为 Date
      * @param calendar
      * @return
      */
     public   static  Date calendar2Date(Calendar calendar) {
         if  (calendar ==  null ) {
             return   null ;
         }
         return  calendar.getTime();
     }

     /**
      * Date 转 换为 Calendar
      * @param date
      * @return
      */
     public   static  Calendar date2Calendar(Date date) {
         if  (date ==  null ) {
             return   null ;
         }
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(date);
         return  calendar;
     }

     /**
      * 拿 到默认格式的SimpleDateFormat
      * @return
      */
     public   static  SimpleDateFormat getSimpleDateFormat() {
         return  getSimpleDateFormat( null );
     }

     /**
      * 拿 到指定输出格式的SimpleDateFormat
      * @param format
      * @return
      */
     public   static  SimpleDateFormat getSimpleDateFormat(String format) {
         SimpleDateFormat sdf;
         if  (format ==  null ) {
             sdf = new  SimpleDateFormat(C_TIME_PATTON_DEFAULT);
         } else  {
             sdf = new  SimpleDateFormat(format);
         }

         return  sdf;
     }

     /**
      * 转 换当前时间为默认格式
      * @return
      */
     public   static  String formatDate2Str() {
         return  formatDate2Str( new  Date());
     }

     /**
      * 转 换指定时间为默认格式
      * @param date
      * @return
      */
     public    static  String formatDate2Str(Date date) {
         return  formatDate2Str(date, C_TIME_PATTON_DEFAULT);
     }

     /**
      * 转 换指定时间为指定格式
      * @param date
      * @param format
      * @return
      */
     public   static  String formatDate2Str(Date date, String format) {
         if  (date ==  null ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }
         SimpleDateFormat sdf = getSimpleDateFormat(format);
         return  sdf.format(date);
     }

     /**
      * 转 换默认格式的时间为Date
      * @param dateStr
      * @return
      */
     public   static  Date formatStr2Date(String dateStr) {
         return  formatStr2Date(dateStr,  null );
     }

     /**
      * 转 换指定格式的时间为Date
      * @param dateStr
      * @param format
      * @return
      */
     public   static  Date formatStr2Date(String dateStr, String format) {
         if  (dateStr ==  null ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }
         SimpleDateFormat sdf = getSimpleDateFormat(format);
         return  sdf.parse(dateStr,  new  ParsePosition( 0 ));
     }

     /**
      * 转 换默认格式的时间为指定格式时间
      * @param dateStr
      * @param defineFormat
      * @return
      */
     public   static  String formatDefault2Define(String dateStr, String defineFormat) {
         return  formatSource2Target(dateStr, C_TIME_PATTON_DEFAULT, defineFormat);
     }

     /**
      * 转 换源格式的时间为目标格式时间
      * @param dateStr
      * @param sourceFormat
      * @param targetFormat
      * @return
      */
     public   static  String formatSource2Target(String dateStr, String sourceFormat, String targetFormat) {
         Date date = formatStr2Date(dateStr, sourceFormat);
         return  formatDate2Str(date, targetFormat);
     }

     /**
      * 计 算当天是该年中的第几周
      * @return
      */
     public   static   int  findWeeksNoInYear() {
         return  findWeeksNoInYear( new  Date());
     }

     /**
      * 计 算指定日期是该年中的第几周
      * @param date
      * @return
      */
     public   static   int  findWeeksNoInYear(Date date) {
         if  (date ==  null ) {
             return   0 ;
         }
         return  findWeeksNoInYear(date2Calendar(date));
     }

     /**
      * 计 算指定日历是该年中的第几周
      * @param calendar
      * @return
      */
     public   static   int  findWeeksNoInYear(Calendar calendar) {
         if  (calendar ==  null ) {
             return   0 ;
         }
         return  calendar.get(Calendar.WEEK_OF_YEAR);
     }

     /**
      * 计 算一年中的第几星期是几号
      * @param year
      * @param weekInYear
      * @param dayInWeek
      * @return
      */
     public   static  Date findDateInWeekOnYear( int  year,  int  weekInYear,  int  dayInWeek) {
         Calendar calendar = Calendar.getInstance();
         if  (year >  0 ) {
             calendar.set(Calendar.YEAR, year);
         }

         calendar.set(Calendar.WEEK_OF_YEAR, weekInYear);
         calendar.set(Calendar.DAY_OF_WEEK, dayInWeek);

         return  calendar.getTime();
     }

     /**
      * 相 对于当前日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param days
      * @return
      */
     public   static  Date dayBefore2Date( int  days) {
         Date date = new  Date();
         return  dayBefore2Object(days,  null , date);
     }

     /**
      * 相 对于当前日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param days
      * @return
      */
     public   static  String dayBefore2Str( int  days) {
         String string = formatDate2Str();
         return  dayBefore2Object(days,  null , string);
     }

     /**
      * 相 对于当前日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param days
      * @param format
      * @param instance
      */
     @SuppressWarnings ( "unchecked" )
     public   static  <T  extends  Object> T dayBefore2Object( int  days, String format, T instance) {
         Calendar calendar = Calendar.getInstance();
         if  (days ==  0 ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }

         calendar.add(Calendar.DATE, days);
         if  (instance  instanceof  Date) {
             return  (T)calendar.getTime();
         } else   if  (instance  instanceof  String) {
             return  (T)formatDate2Str(calendar2Date(calendar), format);
         }
         return   null ;
     }

     /**
      * 相 对于指定日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param date
      * @param days
      * @return
      */
     public   static  Date defineDayBefore2Date(Date date,  int  days) {
         Date dateInstance = new  Date();
         return  defineDayBefore2Object(date, days,  null , dateInstance);
     }

     /**
      * 相 对于指定日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param date
      * @param days
      * @return
      */
     public   static  String defineDayBefore2Str(Date date,  int  days) {
         String stringInstance = formatDate2Str();
         return  defineDayBefore2Object(date, days,  null , stringInstance);
     }

     /**
      * 相 对于指定日期的前几天(days < 0０００００)或者后几天(days > 0)
      * @param <T>
      * @param date
      * @param days
      * @param format
      * @param instance
      * @return
      */
     @SuppressWarnings ( "unchecked" )
     public   static  <T  extends  Object> T defineDayBefore2Object(Date date,
             int  days, String format, T instance) {
         if  (date ==  null  || days ==  0 ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }

         Calendar calendar = date2Calendar(date);
         calendar.add(Calendar.DATE, days);
         if  (instance  instanceof  Date) {
             return  (T)calendar.getTime();
         } else   if  (instance  instanceof  String) {
             return  (T)formatDate2Str(calendar2Date(calendar), format);
         }
         return   null ;
     }

     /**
      * 相 对于当前日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param months
      * @return
      */
     public   static  Date monthBefore2Date( int  months) {
         Date date = new  Date();
         return  monthBefore2Object(months,  null , date);
     }

     /**
      * 相 对于当前日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param months
      * @return
      */
     public   static  String monthBefore2Str( int  months) {
         String string = formatDate2Str();
         return  monthBefore2Object(months,  null , string);
     }

     /**
      * 相 对于当前日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param <T>
      * @param months
      * @param format
      * @param instance
      */
     @SuppressWarnings ( "unchecked" )
     public   static  <T  extends  Object> T monthBefore2Object( int  months, String format, T instance) {
         if  (months ==  0 ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }
         Calendar calendar = Calendar.getInstance();
         calendar.add(Calendar.MONTH, months);

         if  (instance  instanceof  Date) {
             return  (T)calendar.getTime();
         } else   if  (instance  instanceof  String) {
             return  (T)formatDate2Str(calendar2Date(calendar), format);
         }

         return   null ;
     }

     /**
      * 相 对于指定日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param date
      * @param months
      * @return
      */
     public   static  Date defineMonthBefore2Date(Date date,  int  months) {
         Date dateInstance = new  Date();
         return  defineMonthBefore2Object(date, months,  null , dateInstance);
     }

     /**
      * 相 对于指定日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param date
      * @param months
      * @return
      */
     public   static  String defineMonthBefore2Str(Date date,  int  months) {
         String stringInstance = formatDate2Str();
         return  defineMonthBefore2Object(date, months,  null , stringInstance);
     }

     /**
      * 相 对于指定日期的前几月(months < 0０００００)或者后几月(months > 0)时间
      * @param <T>
      * @param date
      * @param months
      * @param format
      * @param instance
      * @return
      */
     @SuppressWarnings ( "unchecked" )
     public   static  <T  extends  Object> T defineMonthBefore2Object(Date date,
             int  months, String format, T instance) {
         if  (months ==  0 ) {
             return   null ;
         }

         if  (format ==  null  || format.equals( "" )) {
             format = C_TIME_PATTON_DEFAULT;
         }

         Calendar calendar = date2Calendar(date);
         calendar.add(Calendar.MONTH, months);

         if  (instance  instanceof  Date) {
             return  (T)calendar.getTime();
         } else   if  (instance  instanceof  String) {
             return  (T)formatDate2Str(calendar2Date(calendar), format);
         }

         return   null ;
     }

     /**
      * 计 算两个日期直接差的天数
      * @param firstDate
      * @param secondDate
      * @return
      */
     public   static   int  caculate2Days(Date firstDate, Date secondDate) {
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(firstDate);
         int  dayNum1 = calendar.get(Calendar.DAY_OF_YEAR);
         calendar.setTime(secondDate);
         int  dayNum2 = calendar.get(Calendar.DAY_OF_YEAR);
         return  Math.abs(dayNum1 - dayNum2);
     }

     /**
      * 计 算两个日期直接差的天数
      * @param firstCalendar
      * @param secondCalendar
      * @return
      */
     public   static   int  caculate2Days(Calendar firstCalendar, Calendar secondCalendar) {
         if  (firstCalendar.after(secondCalendar)) {
             Calendar calendar = firstCalendar;
             firstCalendar = secondCalendar;
             secondCalendar = calendar;
         }

         long  calendarNum1 = firstCalendar.getTimeInMillis();
         long  calendarNum2 = secondCalendar.getTimeInMillis();
         return  Math.abs(( int )((calendarNum1 - calendarNum2)/C_ONE_DAY));
     }

     public   static   void  main(String[] args) {
 //      System.out.println("当前月份的最大天 数:" + findMaxDayInMonth(new Date()));
 //      System.out.println("6月份的最大天 数:" + findMaxDayInMonth(6));
 //      System.out.println("1999-02月份的最大天 数:" + findMaxDayInMonth(1999, 2));
 //      System.out.println("2000-02月份的最大天 数:" + findMaxDayInMonth(2000, 2));

 //      System.out.println(formatSource2Target("2009-07-24 11:02:35", null, "yyyy/MM/dd"));
 //      System.out.println(findWeeksNoInYear());

 //      System.out.println("2003年的第30个星期一是那 天:" + findDateInWeekOnYear(2003, 30, Calendar.MONDAY));
 //      System.out.println("2009年的第30个星期一是那 天:" + findDateInWeekOnYear(2009, 30, Calendar.FRIDAY));

 //      System.out.println("【日期格式】当前日期的前7天 是:" + dayBefore2Date(-7));
 //      System.out.println("【字符格式】当前日期的前7天 是:" + dayBefore2Str(-7));
 //      System.out.println("【日期格式】当前日期的后7天 是:" + dayBefore2Date(7));
 //      System.out.println("【字符格式】当前日期的后7天 是:" + dayBefore2Str(7));

 //      System.out.println(formatStr2Date("2009-07-22", "yyyy-MM-dd"));

 //      System.out.println("【日期格式】2009-07-22的前7天是:" +
 //              defineDayBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), -7));
 //      System.out.println("【字符格式】2009-07-22的前7天是:" +
 //              defineDayBefore2Str(formatStr2Date("2009-07-22", "yyyy-MM-dd"), -7));
 //      System.out.println("【日期格式】2009-07-22的后7天是:" +
 //              defineDayBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), 7));
 //      System.out.println("【字符格式】2009-07-22的后7天是:" +
 //              defineDayBefore2Str(formatStr2Date("2009-07-22", "yyyy-MM-dd"), 7));

 //      System.out.println("【日期格式】相对于当前时间的前2月日期 是:" + monthBefore2Date(-2));
 //      System.out.println("【字符格式】相对于当前时间的前2月日期 是:" + monthBefore2Date(-2));
 //      System.out.println("【日期格式】相对于当前时间的后2月日期 是:" + monthBefore2Date(2));
 //      System.out.println("【字符格式】相对于当前时间的后2月日期 是:" + monthBefore2Date(2));

 //      System.out.println("【日期格式】2009-07-22的前2月日期 是:" +
 //              defineMonthBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), -2));
 //      System.out.println("【字符格式】2009-07-22的前2月日期是:" +
 //              defineMonthBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), -2));
 //      System.out.println("【日期格式】2009-07-22的后2月日期 是:" +
 //              defineMonthBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), 2));
 //      System.out.println("【字符格式】2009-07-22的后2月日期 是:" +
 //              defineMonthBefore2Date(formatStr2Date("2009-07-22", "yyyy-MM-dd"), 2));

 //      Date firstDate = formatStr2Date("2009-07-22", "yyyy-MM-dd");
 //      Date secondDate = formatStr2Date("2009-07-18", "yyyy-MM-dd");
 //      System.out.println(caculate2Days(firstDate, secondDate));

         Calendar firstC = date2Calendar(formatStr2Date("2009-07-22" ,  "yyyy-MM-dd" ));
         Calendar secondC = date2Calendar(formatStr2Date("2009-07-18" ,  "yyyy-MM-dd" ));
         System.out.println(caculate2Days(firstC, secondC));
     }
 }