java天数转毫秒 java毫秒值转日期

   

long sd=1345185923140L;   

         Date dat=new Date(sd);   

         GregorianCalendar gc = new GregorianCalendar();    

         gc.setTime(dat);   

         java.text.SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd hh:mm:ss");   

         String sb=format.format(gc.getTime());   

 //        System.out.println(sb);   

          

       //毫秒转换为日期 

         DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss"); 

         long now = System.currentTimeMillis(); 

         Calendar calendar = Calendar.getInstance(); 

         calendar.setTimeInMillis(now); 

         System.out.println(now + " = " + formatter.format(calendar.getTime())); 

         // 日期转换为毫秒 两个日期想减得到天数 

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

         String start="2011-09-20 12:30:45"; 

         String end ="2011-10-20 6:30:00"; 

         //得到毫秒数 

         long timeEnd = 0; 

         long timeStart = 0; 

try { 

timeStart=sdf.parse(start).getTime(); 

timeEnd = sdf.parse(end).getTime(); 

} catch (ParseException e) { 

// TODO Auto-generated catch block 

e.printStackTrace(); 

} 

         //两个日期想减得到天数 

         long dayCount= (timeEnd-timeStart)/(24*3600*1000); 

         System.out.println(dayCount);