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 Summary

Constructors
Constructor
Description
`XMLFormatter()`
Creates a new instance of XMLFormatter.

## Method Summary

Modifier and Type
Method
Description
`String`
`format(LogRecord record)`
Format the given message to XML.
`String`
`getHead(Handler h)`
Return the header string for a set of XML formatted records.
`String`
`getTail(Handler h)`
Return the tail string for a set of XML formatted records.

### Methods declared in class java.util.logging.Formatter

`formatMessage`

### Methods declared in class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

## 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