Long a = 1447759915523l;
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date= new Date(a);
String d = df.format(date);
System.out.println("d = "+d);
/*date转long*/
String dd = "2015-11-17 11:31:56";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");// 2015-06-05 15:02:03
Date dt = sdf.parse(dd);
long time = dt.getTime();
System.out.println("time = "+time);