Module java.logging
Package java.util.logging

Class XMLFormatter

java.lang.Object
java.util.logging.Formatter
java.util.logging.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.

Since:
1.4

  • Constructor Details

    • XMLFormatter

      public XMLFormatter()
      Creates a new instance of XMLFormatter.
      Implementation Requirements:
      Since JDK 9, the XMLFormatter will print out the record event time as an Instant. This instant has the best resolution available on the system. The <date> element will contain the instant as formatted by the DateTimeFormatter.ISO_INSTANT. In addition, an optional <nanos> element containing a nanosecond adjustment will be printed if the instant contains some nanoseconds below the millisecond resolution.

      This new behavior can be turned off, and the old formatting restored, by specifying a property in the logging configuration. If LogManager.getLogManager().getProperty( this.getClass().getName()+".useInstant") is "false" or "0", the old formatting will be restored.

  • Method Details

    • format

      public String format​(LogRecord record)
      Format the given message to XML.

      This method can be overridden in a subclass. It is recommended to use the Formatter.formatMessage(java.util.logging.LogRecord) convenience method to localize and format the message field.

      Specified by:
      format in class Formatter
      Parameters:
      record - the log record to be formatted.
      Returns:
      a formatted log record

    • getHead

      public String getHead​(Handler h)
      Return the header string for a set of XML formatted records.
      Overrides:
      getHead in class Formatter
      Parameters:
      h - The target handler (can be null)
      Returns:
      a valid XML string

    • getTail

      public String getTail​(Handler h)
      Return the tail string for a set of XML formatted records.
      Overrides:
      getTail in class Formatter
      Parameters:
      h - The target handler (can be null)
      Returns:
      a valid XML string