java时间操作

时间加减

1.用java.util.Calender来实现

  Calendar calendar=Calendar.getInstance();      calendar.setTime(new Date());    System.out.println(calendar.get(Calendar.DAY_OF_MONTH));//今天的日期    calendar.set(Calendar.DAY_OF_MONTH,calendar.get(Calendar.DAY_OF_MONTH)+1);//让日期加1  

2.用java.text.SimpleDateFormat和java.util.Date来实现

 Date d=new Date();      SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");      System.out.println("今天的日期："+df.format(d));      System.out.println("两天前的日期：" + df.format(new Date(d.getTime() - 2 * 24 * 60 * 60 * 1000)));     System.out.println("三天后的日期：" + df.format(new Date(d.getTime() + 3 * 24 * 60 * 60 * 1000)));

3.GregorianCalendar 实现

GregorianCalendar gc=new GregorianCalendar(); gc.setTime(new Date); gc.add(field,value); value为正则往后,为负则往前 field取1加1年,取2加半年,取3加一季度,取4加一周 取5加一天..../**java中对日期的加减操作*gc.add(1,-1)表示年份减一.*gc.add(2,-1)表示月份减一.*gc.add(3.-1)表示周减一.*gc.add(5,-1)表示天减一.*以此类推应该可以精确的毫秒吧.没有再试.大家可以试试.*GregorianCalendar类的add(int field,int amount)方法表示年月日加减.*field参数表示年,月.日等.*amount参数表示要加减的数量.

时间比较*
1.两个string类型的日期比较大小

public static int compare_date(String DATE1, String DATE2) {         DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");         try {             Date dt1 = df.parse(DATE1);             Date dt2 = df.parse(DATE2);             if (dt1.getTime() > dt2.getTime()) {                 System.out.println("dt1 在dt2前");                 return 1;             } else if (dt1.getTime() < dt2.getTime()) {                 System.out.println("dt1在dt2后");                 return -1;             } else {                 return 0;             }         } catch (Exception exception) {             exception.printStackTrace();         }         return 0;     }

2.返回两个string类型日期之间相差的天数

public static int daysBetween(String smdate,String bdate){           SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");           Calendar cal = Calendar.getInstance();             long time1 = 0;         long time2 = 0;         try{              cal.setTime(sdf.parse(smdate));                 time1 = cal.getTimeInMillis();                  cal.setTime(sdf.parse(bdate));               time2 = cal.getTimeInMillis();           }catch(Exception e){             e.printStackTrace();         }         long between_days=(time2-time1)/(1000*3600*24);          return Integer.parseInt(String.valueOf(between_days));          }

3.返回两个string类型日期相差的小时数

public static int daysBetween2(String startTime, String endTime) {          SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH");            Calendar cal = Calendar.getInstance();              long time1 = 0;          long time2 = 0;          try{               cal.setTime(sdf.parse(startTime));                  time1 = cal.getTimeInMillis();                   cal.setTime(sdf.parse(endTime));                time2 = cal.getTimeInMillis();            }catch(Exception e){              e.printStackTrace();          }          long between_days=(time2-time1)/(1000*3600);           return Integer.parseInt(String.valueOf(between_days));           }

4.计算两段日期的重合日期

/**     * 计算两段日期的重合日期     * @param str1 开始日期1     * @param str2 结束日期1     * @param str3 开始日期2     * @param str4 结束日期2     * @return     * @throws Exception     */    public static Map<String,Object> comparisonRQ(String str1, String str2, String str3,            String str4) throws Exception {        String mesg = "";        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");        String startdate = "";        String enddate = "";        try {            Date dt1 = df.parse(str1);            Date dt2 = df.parse(str2);            Date dt3 = df.parse(str3);            Date dt4 = df.parse(str4);            if (dt1.getTime()<=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {                mesg = "f";//重合                startdate = str3;                enddate = str2;            }            if (dt1.getTime()>=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {                mesg = "f";//重合                startdate = str1;                enddate = str2;            }            if (dt3.getTime()<=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {                mesg = "f";//重合                startdate = str1;                enddate = str4;            }            if (dt3.getTime()>=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {                mesg = "f";//重合                startdate = str3;                enddate = str4;            }            System.out.println(startdate+"----"+enddate);        }catch (ParseException e) {            e.printStackTrace();            throw new ParseException(e.getMessage(), 0);        }catch(Exception e){            e.printStackTrace();            throw new Exception(e);        }        Map<String,Object> map = new HashMap<String,Object>();        map.put("startdate", startdate);        map.put("enddate", enddate);        return map;    }