正如在“下层客户端的向后兼容性”部分中提到的日期时间偏移文档 https://msdn.microsoft.com/en-CA/library/bb630289.aspx,我们可以使用字符串表示datetimeoffset
价值观。事实上,如果我们检索一个datetimeoffset
jTDS 1.3.1 的值我们得到java.lang.String
形式的价值
YYYY-MM-DD hh:mm:ss[.nnnnnnn] {+|-}hh:mm
这样的值可以这样解析:
// rs is our ResultSet object
String valueRetrieved = rs.getString(1); // e.g., "2016-12-08 12:34:56.7850000 -07:00"
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSSS ZZZZZ");
ZonedDateTime zdt = ZonedDateTime.parse(valueRetrieved, dtf);
至于写一个datetimeoffset
值到 SQL Server,jTDS 无法使用以下命令正确处理更新.setTimestamp
,例如,在我的机器上......
java.sql.Timestamp ts = java.sql.Timestamp.valueOf("2016-12-08 12:34:56.785"); // local
String tsString = formatTimestampForDateTimeOffset(ts); // (see below)
System.out.printf(" java.sql.TimeStamp value: %s (%d ms since epoch)%n", tsString, ts.getTime());
System.out.println();
System.out.println("Saving via setTimestamp ...");
String sqlUpdate = "UPDATE dtoTable SET dtoCol = ? WHERE id=1";
try (PreparedStatement s = conn.prepareStatement(sqlUpdate)) {
s.setTimestamp(1, ts); // pass the Timestamp itself
s.executeUpdate();
}
String valueRetrieved;
try (
Statement s = conn.createStatement();
ResultSet rs = s.executeQuery("SELECT dtoCol FROM dtoTable WHERE id=1")) {
rs.next();
valueRetrieved = rs.getString(1);
System.out.printf(" jTDS saved the TimeStamp value as: %s%n", valueRetrieved);
}
...产生...
java.sql.TimeStamp value: 2016-12-08 12:34:56.785 -07:00 (1481225696785 ms since epoch)
Saving via setTimestamp ...
jTDS saved the TimeStamp value as: 2016-12-08 12:34:56.7870000 +00:00
...这不仅错误地将时区偏移设置为+00:00(没有更改日期/时间值本身),而且还增加了几毫秒只是为了好玩。
但是,如果我们将时间戳值转换为格式正确的字符串,例如......
public static String formatTimestampForDateTimeOffset(java.sql.Timestamp ts) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS ZZZZZ");
String s = sdf.format(new Date(ts.getTime()));
// T-SQL *requires* the colon in the timezone offset: -07:00, not -0700
int colonPosition = s.length() - 2;
return s.substring(0, colonPosition) + ":" + s.substring(colonPosition);
}
...并使用.setString
代替.setTimestamp
,那么datetimeoffset
值已正确保存:
Saving via setString ...
jTDS saved the formatted String as: 2016-12-08 12:34:56.7850000 -07:00
parsed to ZonedDateTime: 2016-12-08T12:34:56.785-07:00
converted to Instant: 2016-12-08T19:34:56.785Z
converted to java.util.Date: Thu Dec 08 12:34:56 MST 2016