Convert java Date to dbf FoxPro datetime format

问题:

Im trying to create DBF file in FoxPro spec, but idk how to insert date. I dont know how to convert java Date to this:

FoxPro's field is 2 32bit integers: one stores the date, the other stores the time, stored in reverse byte order. The date integer stores the number of days from 1/1/4712BC. The time integer stores the number of milliseconds from 00:00:00.

Its easy to get days and milliseconds with JodaTime:

         DateTime start = new DateTime(-4713, 1, 1, 0, 0, 0, 0);
         DateTime end = new DateTime(2014, 1, 1, 0, 0, 0, 0);
         Days days = Days.daysBetween(start, end);
         long millis = end.getMillisOfDay();

but how to convert this info to needed format? For input a date I just use:

SimpleDateFormat simpledateformat = new SimpleDateFormat("yyyyMMdd");
simpledateformat.format(date);

and its work fine, but when I try use datetime with "yyyyMMddHHmmss" I see very bad result, like 17.08.33409 12:34:20 (only month is correct).

回答1:

VFP has both Date and DateTime field types.

The VFP syntax for inserting a date is:

Insert into mytable (mydatefield) values ({^YYYY-MM-DD})

or

Insert into mytable (mydatefield) values (Date(YYYY,MM,DD))

And for a datetime (assuming the field in VFP is a datetime)

Insert into mytable (mydatefield) values ({^YYYY-MM-DD HH:MM:SS})

or

Insert into mytable (mydatefield) values (DateTime(YYYY,MM,DD,HH,MM,SS)) 

So assuming you can extract a text representation of the year, month and day from your Java date you can build up your VFP query from that.