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

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

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https://docs.oracle.com/en/java/javase/17/docs/api/java.logging/java/util/logging/XMLFormatter.html