java时间

//根据输入的日期(MM/dd/yyyy)返回最近7天的日期
public static List<String> getNextSevenDate(String dateStr,String dateFormat)
{
   List<String> dateList=new ArrayList<String>();
   Date date=new Date(dateStr);
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(date);
   SimpleDateFormat sdf=new SimpleDateFormat(dateFormat);
   dateList.add(dateStr);
   for(int i=0;i<6;i++)
   {
   calendar.add(Calendar.DATE,1);
   dateList.add(sdf.format(calendar.getTime()));
   }
   return dateList;
}


SimpleDateFormat sdf  =   new  SimpleDateFormat( " yyyy-MM-dd HH:mm:ss " ); 

这一行最重要，它确立了转换的格式，yyyy是完整的公元年，MM是月份，dd是日期，至于HH:mm:ss就不需要我再解释了吧！

ps:为什么有的格式大写，有的格式小写，那是怕避免混淆，例如MM是月份，mm是分；HH是24小时制，而hh是12小时制

1.字符串转日期：
　
2002-10-8 15:30:22要把它转成日期，可以用

Date date = sdf.parse( " 2002-10-8 15:30:22 " );

2.日期转字符串

假如把今天的日期转成字符串可用


String datestr = sdf.format( new  Date()); 

　这个字符串的内容便类似2002-10-08 14:55:38

透过这个API我们便可以随心所欲的将日期转成我们想要的字符串格式，例如希望将日期输出成2002年10月08日，

我们可以这么写：

SimpleDateFormat sdf  =   new  SimpleDateFormat( " yyyy年MM月dd日 " );
    String datestr = sdf.format( new  Date()); 




//随机数
//生成 [0-n) 个不重复的随机数
        //list 用来保存这些随机数
        ArrayList list = new ArrayList();
        int n = 10;
        Random rand = new Random();
        boolean[] bool = new boolean[n];
        int num =0;
        for (int i = 0; i<n; i++){
            do{
            //如果产生的数相同继续循环
             num = rand.nextInt(n);   
            }while(bool[num]);
            bool[num] =true;
            list.add(num);
        }
        System.out.println (list);   
    }

获取当前时间：
1.
String[] weekDayArray={"日","一","二","三","四","五","六"};
Calendar calendar=Calendar.getInstance();
System.out.println(calendar.getTime());
            int year=calendar.get(Calendar.YEAR);
            int month=calendar.get(Calendar.MONTH);
            int day=calendar.get(Calendar.DATE);
            int weekDay=calendar.get((Calendar.DAY_OF_WEEK));
            int am_pm=calendar.get(Calendar.AM_PM);
            int hour=calendar.get(Calendar.HOUR_OF_DAY);
            int minute=calendar.get(Calendar.MINUTE);
            int second=calendar.get(Calendar.SECOND);
            String dateStr=year+"年"+(month+1)+"月"+day+"日"+" 星期"+weekDayArray[weekDay-1];
            if (am_pm==Calendar.AM){dateStr+=" 上午";
            }                else{                        dateStr+=" 下午";
            }               
            dateStr+=hour+"时"+minute+"分"+second+"秒";
            System.out.println("dd"+dateStr);
2.
Date d=new Date();
            SimpleDateFormat   sdf   =   new   SimpleDateFormat    ( "yyyyMMddHHmmss");
            System.out.println(sdf.format(d));

public static final String FormatDayToChinaTime24H = "yyyy年MM月dd日";  
 
    /** 
     * 将yyyy-mm-dd转为yyyy-m-d 
     *  
     * @param day 
     *            距离现在之后的天数 
     * @return Date:距离现在之后的若干天的日期; 
     */ 
    public static String getYMDDays(String day){  
        String dayTime=day;  
        if(String.valueOf(day.charAt(8)).equals("0"))dayTime=day.substring(0,8)+day.substring(9);  
        if(String.valueOf(day.charAt(5)).equals("0"))dayTime=dayTime.substring(0,5)+dayTime.substring(6);  
        return dayTime;  
    }  
      
      
    /** 
     * 两个日期间的天数 
     *  
     * @param days 
     *            距离现在之后的天数 
     * @return Date:距离现在之后的若干天的日期; 
     */ 
    public static int getIntervalDays(Date startday,Date endday){          
        if(startday.after(endday)){  
            Date cal=startday;  
            startday=endday;  
            endday=cal;  
        }          
        long sl=startday.getTime();  
        long el=endday.getTime();         
        long ei=el-sl;             
        return (int)(ei/(1000*60*60*24));  
    }  
 
      
      
    /** 
     * 取得距离现在多少天（距离现在之后的若干天） 
     *  
     * @param days 
     *            距离现在之后的天数 
     * @return Date:距离现在之后的若干天的日期; 
     */ 
    public static Date getDate(int days) {  
        Date dateresult = new Date();  
        try {  
            DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.FULL);  
            // Create our Gregorian Calendar.  
            GregorianCalendar cal = new GregorianCalendar();  
 
            // Set the date and time of our calendar  
            // to the system&s date and time  
            cal.setTime(new Date());  
            cal.add(GregorianCalendar.DAY_OF_MONTH, days);  
            dateresult = cal.getTime();  
        } catch (Exception e) {  
            System.out.println("exception" + e.toString());  
        }  
        return dateresult;  
    }  
 
    /** 
     * @根据当前日期计算n天后的日期 
     * @return String 
     */ 
    public static Date afterNDay(Date date, int n) {  
        Calendar c = Calendar.getInstance();  
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");  
        c.setTime(date);  
        c.add(Calendar.DATE, n);  
        Date d2 = c.getTime();  
        // String s=df.format(d2);  
        return d2;  
    }  
      
    /** 
     * @根据当前日期计算n天后的日期 
     * @return String 
     */ 
    public static String afterDay(Date date, int n) {  
        Calendar c = Calendar.getInstance();  
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");  
        // String s=df.format(d2);  
        return df.toString();  
    }  
 
    /** 
     * @获取当前时间是星期几，“星期日” 
     * @return String 
     */ 
    public static String getDayInWeek() {  
        Date today = new Date(System.currentTimeMillis());  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("E");  
        return simpleDateFormat.format(today);  
    }  
    /** 
     *  
     * @跟具字符串时间来获得星期几，(SimpleDateFormat("yyyy-MM-dd")) 
     * @return 
     */ 
public static String getDayInWeek(String mydatestring) {  
     SimpleDateFormat   dateFormat   =   new   SimpleDateFormat("yyyy-MM-dd");     
     Date   date   =   null;   
     String   showDate   ="";   
     try   {     
             date   =   dateFormat.parse(mydatestring);     
     }   catch   (ParseException   e)   {     
 
     }     
     Calendar   cd   =   Calendar.getInstance();     
     cd.setTime(date);     
     int   mydate   =   cd.get(Calendar.DAY_OF_WEEK);     
      
     switch   (mydate)   {     
     case   1:     
             showDate   =   "星期日";     
             break;     
     case   2:     
             showDate   =   "星期一";     
             break;     
     case   3:     
             showDate   =   "星期二";     
             break;     
     case   4:     
             showDate   =   "星期三";     
             break;     
     case   5:     
             showDate   =   "星期四";     
             break;     
     case   6:     
             showDate   =   "星期五";     
             break;     
     default:     
             showDate   =   "星期六";     
             break;     
     }     
 
    return showDate;  
      
}  
    /** 
     * @根据日期时间，获取当前时间是星期几，“星期日” 
     * @return String 
     */ 
    public static String getDayInWeek(Date date) {  
        if (date == null)  
            return "";  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("E");  
        return simpleDateFormat.format(date);  
    }  
 
    /** 
     * @获取当前时间在这个月的天 
     * @return String 
     */ 
    public static String getDayInMonth() {  
        Date today = new Date(System.currentTimeMillis());  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("d");  
        return simpleDateFormat.format(today);  
    }  
 
    /** 
     * @根据日期，获取当前时间在这个月的天 
     * @return String 
     */ 
    public static String getDayInMonth(Date date) {  
        if (date == null)  
            return "";  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("d");  
        return simpleDateFormat.format(date);  
    }  
 
    /** 
     * @根据在本年当中，获取月份格式"M" 
     * @return String 
     */ 
    public static String getMonthInYear() {  
        Date today = new Date(System.currentTimeMillis());  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("M");  
        return simpleDateFormat.format(today);  
    }  
 
    /** 
     * @根据在本年当中，获取月份格式"MM" 
     * @return String 
     */ 
    public static String getMonthInYear2() {  
        java.util.Date today = new Date(System.currentTimeMillis());  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MM");  
        return simpleDateFormat.format(today);  
    }  
 
    /** 
     * @根据日期，获取月份格式"MM" 
     * @return String 
     */ 
    public static String getMonthInYear2(String formatDate) {  
        java.util.Date day = getDate(formatDate, "yyyy-MM-dd");  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MM");  
        return simpleDateFormat.format(day);  
    }  
 
    /** 
     * @获取当前时间的年，格式"yyyy" 
     * @return String 
     */ 
    public static String getYear() {  
        java.util.Date today = new java.util.Date(System.currentTimeMillis());  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy");  
        return simpleDateFormat.format(today);  
    }  
 
    /** 
     * @根据时间，获取年，格式"yyyy" 
     * @return String 
     */ 
    public static String getYear(String formatDate) {  
        java.util.Date day = getDate(formatDate, "yyyy-MM-dd");  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy");  
        return simpleDateFormat.format(day);  
    }  
 
    /** 
     * @根据日期以及日期格式，获取日期字符串表达 
     * @return String 
     */ 
    public static String getFormatDate(java.util.Date thisDate, String format) {  
        if (thisDate == null)  
            return "";  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);  
        return simpleDateFormat.format(thisDate);  
    }  
 
    /** 
     * @根据日期以及日期格式，获取日期 
     * @return String 
     */ 
    public static java.util.Date getDate(String date, String format) {  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);  
        try {  
            return simpleDateFormat.parse(date);  
        } catch (ParseException ex) {  
            return null;  
        }  
    }  
 
    /** 
     * @返回系统当前月的第一天所表示的日期 
     * @param monthDate 
     *            Date 
     * @return Date 
     */ 
    public static java.util.Date getFirstDateMonth() {  
        try {  
            String date_s = getYear() + "-" + getMonthInYear2() + "-01";  
            return getDate(date_s, "yyyy-MM-dd");  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @返回系统当前月的第一天所表示的日期 
     * @param monthDate 
     *            Date 
     * @return Date 
     */ 
    public static java.util.Date getFirstDateMonth(String formatDate) {  
        try {  
            String date_s = getYear(formatDate) + "-" 
                    + getMonthInYear2(formatDate) + "-01";  
            return getDate(date_s, "yyyy-MM-dd");  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @返回系统当前月的第一天所表示的日期 
     * @param monthDate 
     *            Date 
     * @return Date 
     */ 
    public static String getFirstDateMonthToString() {  
        try {  
            return getYear() + "-" + getMonthInYear2() + "-01";  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @返回系统当前月的第一天所表示的日期 
     * @param monthDate 
     *            Date 
     * @return Date 
     */ 
    public static String getFirstDateMonthToString(String formatDate) {  
        try {  
            return getYear(formatDate) + "-" + getMonthInYear2(formatDate)  
                    + "-01";  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @返回系统当前月的最后一天所表示的日期 
     * @return Date 
     */ 
    public static java.util.Date getLastDateMonth() {  
        try {  
            int lastday = getDaySumInTheMonth();  
            String date_s;  
            if (lastday < 10)  
                date_s = getYear() + "-" + getMonthInYear2() + "-0" + lastday;  
            else 
                date_s = getYear() + "-" + getMonthInYear2() + "-" + lastday;  
            return getDate(date_s, "yyyy-MM-d");  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @返回系统当前月的最后一天所表示的日期 
     * @return Date 
     */ 
    public static String getLastDateMonthToString(String formatDate) {  
        try {  
            int lastday = getDaySumInTheMonth(formatDate);  
            if (lastday < 10)  
                return getYear(formatDate) + "-" + getMonthInYear2(formatDate)  
                        + "-0" + lastday;  
            else 
                return getYear(formatDate) + "-" + getMonthInYear2(formatDate)  
                        + "-" + lastday;  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @根据时间，返回最后一天所表示的日期 
     * @param formatDate 
     *            String 
     * @return Date 
     */ 
    public static java.util.Date getLastDateMonth(String formatDate) {  
        try {  
            int lastday = getDaySumInTheMonth(formatDate);  
            String month = getMonthInYear2(formatDate);  
            String year = getYear(formatDate);  
            String date_s;  
            if (lastday < 10)  
                date_s = year + "-" + month + "-0" + lastday;  
            else 
                date_s = year + "-" + month + "-" + lastday;  
 
            System.out.println(date_s);  
 
            return getDate(date_s, "yyyy-MM-d");  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
        return null;  
    }  
 
    /** 
     * @获得这个月的天数 
     * @return int 
     */ 
    public static int getDaySumInTheMonth() {  
        String month = DayFormat.getMonthInYear();  
        if (month.equalsIgnoreCase("12"))  
            return 31;  
        int mon = Integer.parseInt(month);  
        java.util.Date date = DayFormat.getDate(DayFormat.getYear() + "-" 
                + (mon + 1) + "-" + "1", "yyyy-MM-d");  
        Calendar cal = Calendar.getInstance();  
        cal.setTime(date);  
        cal.add(Calendar.DATE, -1);  
        return Integer.parseInt(new SimpleDateFormat("dd")  
                .format(cal.getTime()));  
    }  
 
    /** 
     * @获得所在日期月份的天数 
     * @return int 
     */ 
    public static int getDaySumInTheMonth(java.util.Date date) {  
        String month = new SimpleDateFormat("MM").format(date);  
        if (month.equalsIgnoreCase("12"))  
            return 31;  
        int mon = Integer.parseInt(month);  
        java.util.Date date2 = DayFormat.getDate(new SimpleDateFormat("yyyy")  
                .format(date)  
                + "-" + (mon + 1) + "-" + "1", "yyyy-MM-d");  
        Calendar cal = Calendar.getInstance();  
        cal.setTime(date2);  
        cal.add(Calendar.DATE, -1);  
        return Integer.parseInt(new SimpleDateFormat("dd")  
                .format(cal.getTime()));  
    }  
 
    /** 
     * @获得所在日期月份的天数 
     * @return int 
     */ 
    public static int getDaySumInTheMonth(String formatDate) {  
        String month = DayFormat.getMonthInYear2(formatDate);  
        if (month.equalsIgnoreCase("12"))  
            return 31;  
        int mon = Integer.parseInt(month);  
        java.util.Date date = DayFormat.getDate(DayFormat.getYear(formatDate)  
                + "-" + (mon + 1) + "-" + "1", "yyyy-MM-d");  
        Calendar cal = Calendar.getInstance();  
        cal.setTime(date);  
        cal.add(Calendar.DATE, -1);  
        return Integer.parseInt(new SimpleDateFormat("dd")  
                .format(cal.getTime()));  
    }  
 
    /** 
     * @把日期格式转换成字符串格式,格式为'yyyy-MM-dd' 
     * @param date 
     *            Date 
     * @return String 
     */ 
    public static String getFormatDate(java.util.Date date) {  
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");  
        return simpleDateFormat.format(date);  
    }  
 
    public final static String FormatDay1 = "yyyy-MM-dd";  
    public final static String FormatDay2 = "yyyy年MM月dd日";  
    public final static String FormatDay3 = "yyyy年MM月dd日 HH:mm:ss";  
    public final static String FormatDay4 = "yyyy-MM-dd HH:mm";  
 
    public static final String Format24Datetime1 = "yyyy-MM-dd HH:mm:ss";// 24  
 
    public static final String Format12Datetime1 = "yyyy-MM-dd hh:mm:ss";// 12  
 
    /** 
     * 获取当前时间 
     *  
     * @return 
     */ 
    public static String getToday() {  
        return getToday(FormatDay1);  
    }  
 
    public static java.sql.Timestamp getCurrentTimestamp() {  
        return new Timestamp(System.currentTimeMillis());  
    }  
 
    public static java.util.Date getCurrentUtilDate() {  
        return new java.util.Date(System.currentTimeMillis());  
    }  
 
    public static String getToday(String formatDay) {  
        java.util.Date today = new java.util.Date();  
        SimpleDateFormat df = new SimpleDateFormat(formatDay);  
        return df.format(today).toString();  
    }  
 
    public static String get24DateTime() {  
        return get24DateTime(Format24Datetime1);  
    }  
 
    public static String get24DateTime(String format24DateTime) {  
        java.util.Date today = new java.util.Date();  
        SimpleDateFormat df = new SimpleDateFormat(format24DateTime);  
        return df.format(today).toString();  
    }  
 
    public static String get12DateTime() {  
        return get12DateTime(Format12Datetime1);  
    }  
 
    public static String get12DateTime(String format12DateTime) {  
        java.util.Date today = new java.util.Date();  
        SimpleDateFormat df = new SimpleDateFormat(format12DateTime);  
        return df.format(today).toString();  
    }  
 
    public static String get24DateTime(Timestamp timestamp) {  
        SimpleDateFormat df = new SimpleDateFormat(Format24Datetime1);  
        return df.format(timestamp).toString();  
    }  
 
    public static String get12DateTime(Timestamp timestamp) {  
        SimpleDateFormat df = new SimpleDateFormat(Format12Datetime1);  
        return df.format(timestamp).toString();  
    }  
 
    // STRING到日期  
    public static java.sql.Date stringToDate(String dateStr) {  
        return java.sql.Date.valueOf(dateStr);  
    }  
 
    public static java.sql.Timestamp stringToTimestamp(String timestampStr) {  
        if (timestampStr == null || timestampStr.length() < 1)  
            return null;  
        return java.sql.Timestamp.valueOf(timestampStr);  
    }  
 
    public static java.sql.Timestamp stringToTimestamp2(String dateStr) {  
        if (dateStr == null || dateStr.length() < 1)  
            return null;  
        return java.sql.Timestamp.valueOf(dateStr + " 00:00:00.000000000");  
    }  
 
    public static java.sql.Timestamp stringToTimestamp3(String dateStr) {  
        if (dateStr == null || dateStr.length() < 1)  
            return null;  
        return java.sql.Timestamp.valueOf(dateStr + ":00.000000000");  
    }  
 
    public static java.sql.Time stringToTime(String timeStr) {  
        return java.sql.Time.valueOf(timeStr);  
    }  
 
    // 日期到STRING  
    public static String dateToString(java.sql.Date datee) {  
        return datee.toString();  
    }  
 
    public static String timestampToString(java.sql.Timestamp timestampe) {  
        return timestampe.toString();  
    }  
 
    public static String timestampToStringForFormat(Timestamp timestamp,  
            String format) {  
        if (timestamp == null)  
            return "";  
        SimpleDateFormat df = new SimpleDateFormat(format);  
        return df.format(timestamp).toString();  
    }  
 
    public static String getTimestampToDateTime15Len(  
            java.sql.Timestamp timestampe) {  
        if (timestampe == null || timestampe.toString().length() < 1)  
            return "";  
        return timestampe.toString().substring(0, 16);  
    }  
 
    public static String timeToString(java.sql.Time timee) {  
        return timee.toString();  
    }  
 
    public static java.sql.Timestamp StringToTimestamp(String dateString)  
            throws ParseException {  
        java.text.SimpleDateFormat formatter = new java.text.SimpleDateFormat(  
                FormatDay1);  
        formatter.setLenient(false);  
        return new java.sql.Timestamp((formatter.parse(dateString).getTime()));  
    }  
 
    public static java.sql.Timestamp StringToTimestampAll(String dateString)  
            throws ParseException {  
        return java.sql.Timestamp.valueOf(dateString);  
    }  
    //获得周日的日期   
    public   static   String   getSunday(Date   date){     
        Calendar   c   =   Calendar.getInstance();     
        c.setTime(date);     
        c.set(Calendar.DAY_OF_WEEK,Calendar.SUNDAY);     
        return   new   SimpleDateFormat("yyyy-MM-dd").format(c.getTime());     
      }      
      //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());     
      }     
      //获得周二的日期  
      public   static   String   getTuesday(Date   date){     
          Calendar   c   =   Calendar.getInstance();     
          c.setTime(date);     
          c.set(Calendar.DAY_OF_WEEK,Calendar.TUESDAY);     
          return   new   SimpleDateFormat("yyyy-MM-dd").format(c.getTime());     
        }   
      //获得周三的日期   
      public   static   String   getWednesday(Date   date){     
          Calendar   c   =   Calendar.getInstance();     
          c.setTime(date);     
          c.set(Calendar.DAY_OF_WEEK,Calendar.WEDNESDAY);     
          return   new   SimpleDateFormat("yyyy-MM-dd").format(c.getTime());     
        }   
      //获得周四的日期  
      public   static   String   getThursday(Date   date){     
          Calendar   c   =   Calendar.getInstance();     
          c.setTime(date);     
          c.set(Calendar.DAY_OF_WEEK,Calendar.THURSDAY);     
          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());         
      }     
      //获得周六的日期   
      public   static   String   getSaturday(Date   date){     
          Calendar   c   =   Calendar.getInstance();     
          c.setTime(date);     
          c.set(Calendar.DAY_OF_WEEK,Calendar.SATURDAY);     
          return   new   SimpleDateFormat("yyyy-MM-dd").format(c.getTime());     
        }   
   
    public static void main(String args[]) {  
        try {  
            String d = "2007-05-15 19:23:48.703";  
            System.out.println(d);  
            java.sql.Timestamp timestampe = java.sql.Timestamp.valueOf(d);  
            System.out.println(timestampe.toString());  
        } catch (Exception er) {  
            er.printStackTrace();  
        }  
    }