Force Java timezone as GMT/UTC

I need to force any time related operations to GMT/UTC, regardless the timezone set on the machine. Any convenient way to so in code?

To clarify, I'm using the DB server time for all operations, but it comes out formatted according to local timezone.

Thanks!

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The OP answered this question to change the default timezone for a single instance of a running JVM, set the user.timezone system property:

java -Duser.timezone=GMT ... <main-class>

If you need to set specific time zones when retrieving Date/Time/Timestamp objects from a database ResultSet , use the second form of the getXXX methods that takes a Calendar object:

Calendar tzCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
ResultSet rs = ...;
while (rs.next()) {
    Date dateValue = rs.getDate("DateColumn", tzCal);
    // Other fields and calculations
}

Or, setting the date in a PreparedStatement:

Calendar tzCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
PreparedStatement ps = conn.createPreparedStatement("update ...");
ps.setDate("DateColumn", dateValue, tzCal);
// Other assignments
ps.executeUpdate();

These will ensure that the value stored in the database is consistent when the database column does not keep timezone information.

The java.util.Date and java.sql.Date classes store the actual time (milliseconds) in UTC. To format these on output to another timezone, use SimpleDateFormat . You can also associate a timezone with the value using a Calendar object:

TimeZone tz = TimeZone.getTimeZone("<local-time-zone>");
//...
Date dateValue = rs.getDate("DateColumn");
Calendar calValue = Calendar.getInstance(tz);
calValue.setTime(dateValue);

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Also if you can set JVM timezone this way

System.setProperty("user.timezone", "EST");

or -Duser.timezone=GMT in the JVM args.

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I had to set the JVM timezone for Windows 2003 Server because it always returned GMT for new Date();

-Duser.timezone=America/Los_Angeles

Or your appropriate time zone. Finding a list of time zones proved to be a bit challenging also...

Here are two list;

http://wrapper.tanukisoftware.com/doc/english/prop-timezone.html

http://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=%2Frzatz%2F51%2Fadmin%2Freftz.htm

链接地址: http://www.djcxy.com/p/29330.html

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