Module java.logging

Class XMLFormatter


public class XMLFormatter extends Formatter
Format a LogRecord into a standard XML format.

The DTD specification is provided as Appendix A to the Java Logging APIs specification.

The XMLFormatter can be used with arbitrary character encodings, but it is recommended that it normally be used with UTF-8. The character encoding can be set on the output Handler.

Implementation Requirements:
Since JDK 9, instances of LogRecord contain an Instant which can have nanoseconds below the millisecond resolution. The DTD specification has been updated to allow for an optional <nanos> element. By default, the XMLFormatter will compute the nanosecond adjustment below the millisecond resolution (using LogRecord.getInstant().getNano() % 1000_000) - and if this is not 0, this adjustment value will be printed in the new <nanos> element. The event instant can then be reconstructed using Instant.ofEpochSecond(millis/1000L, (millis % 1000L) * 1000_000L + nanos) where millis and nanos represent the numbers serialized in the <millis> and <nanos> elements, respectively.
The <date> element will now contain the whole instant as formatted by the DateTimeFormatter.ISO_INSTANT formatter.

For compatibility with old parsers, XMLFormatters can be configured to revert to the old format by specifying a <xml-formatter-fully-qualified-class-name>.useInstant = false property in the logging configuration. When useInstant is false, the old formatting will be preserved. When useInstant is true (the default), the <nanos> element will be printed and the <date> element will contain the formatted instant.

For instance, in order to configure plain instances of XMLFormatter to omit the new <nano> element, java.util.logging.XMLFormatter.useInstant = false can be specified in the logging configuration.