How to format a java.sql.Timestamp(yyyy-MM-dd HH:mm:ss.S) to a date(yyyy-MM-dd HH:mm:ss)

问题

Well, I'm having a detail using a Date, because I'm getting an Object from my DataBase and in the variable "fecha" (date) from that same object I'm getting a java.sql.Timestamp, so the formatt is with miliseconds, but i don't want the miliseconds to appear. So i need to formatt the date that I'm receiving from my DB to a new date that doesn't have miliseconds.

This is the object Factura:

public class Factura  implements java.io.Serializable {

 private FacturaId id;
 ...
 private boolean activo;
 private Date fecha;
}

In the xml that is mapped to the DB I have this code for that variable "fecha":

<property name="fecha" type="timestamp">
  <column length="19" name="fecha" not-null="true"/>
</property>

In the Database that column is fecha DATETIME.

And when I get an object Factura from my DB I'm getting this kind of date 2013-10-10 10:49:29.0 but I want it without the .0 (miliseconds).

I've tried this (factura is the Factura object):

try {
   SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
   Date fechaNueva = null;
   String fechaStr = factura.getFecha().toString();
   int tamaño = fechaStr.length()-2;
   fechaStr = fechaStr.substring(0, tamaño); //I get a string without the miliseconds
   fechaNueva = format.parse(fechaStr);
} catch(ParseException ex) {
   ...
}

But fechaNueva is giving me Thu Oct 10 10:49:29 CDT 2013 and I only want 2013-10-10 10:49:29, can you help me, please?

Thanks a lot, in advance.

回答1:

You do not need to use substring at all since your format doesn't hold that info.

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String fechaStr = "2013-10-10 10:49:29.10000";  
Date fechaNueva = format.parse(fechaStr);

System.out.println(format.format(fechaNueva)); // Prints 2013-10-10 10:49:29

回答2:

A date-time object is not a String

The java.sql.Timestamp class has no format. Its toString method generates a String with a format.

Do not conflate a date-time object with a String that may represent its value. A date-time object can parse strings and generate strings but is not itself a string.

java.time

First convert from the troubled old legacy date-time classes to java.time classes. Use the new methods added to the old classes.

Instant instant = mySqlDate.toInstant() ;

Lose the fraction of a second you don't want.

instant = instant.truncatedTo( ChronoUnit.Seconds );

Assign the time zone to adjust from UTC used by Instant.

ZoneId z = ZoneId.of( "America/Montreal" ) ;
ZonedDateTime zdt = instant.atZone( z );

Generate a String close to your desired output. Replace its T in the middle with a SPACE.

DateTimeFormatter f = DateTimeFormatter.ISO_LOCAL_DATE_TIME ;
String output = zdt.format( f ).replace( "T" , " " );

来源：https://stackoverflow.com/questions/19544067/how-to-format-a-java-sql-timestampyyyy-mm-dd-hhmmss-s-to-a-dateyyyy-mm-dd-h