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package java.util.logging;
import java.nio.charset.Charset;
import java.time.Instant;
import java.time.format.DateTimeFormatter;
import java.util.*;
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
/**
* Format a LogRecord into a standard XML format.
* <p>
* The DTD specification is provided as Appendix A to the
* Java Logging APIs specification.
* <p>
* 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.
*
* @implSpec Since JDK 9, instances of {@linkplain LogRecord} contain
* an {@link LogRecord#getInstant() Instant} which can have nanoseconds below
* the millisecond resolution.
* The DTD specification has been updated to allow for an optional
* {@code <nanos>} element. By default, the XMLFormatter will compute the
* nanosecond adjustment below the millisecond resolution (using
* {@code LogRecord.getInstant().getNano() % 1000_000}) - and if this is not 0,
* this adjustment value will be printed in the new {@code <nanos>} element.
* The event instant can then be reconstructed using
* {@code Instant.ofEpochSecond(millis/1000L, (millis % 1000L) * 1000_000L + nanos)}
* where {@code millis} and {@code nanos} represent the numbers serialized in
* the {@code <millis>} and {@code <nanos>} elements, respectively.
* <br>
* The {@code <date>} element will now contain the whole instant as formatted
* by the {@link DateTimeFormatter#ISO_INSTANT DateTimeFormatter.ISO_INSTANT}
* formatter.
* <p>
* For compatibility with old parsers, XMLFormatters can
* be configured to revert to the old format by specifying a
* {@code <xml-formatter-fully-qualified-class-name>.useInstant = false}
* {@linkplain LogManager#getProperty(java.lang.String) property} in the
* logging configuration. When {@code useInstant} is {@code false}, the old
* formatting will be preserved. When {@code useInstant} is {@code true}
* (the default), the {@code <nanos>} element will be printed and the
* {@code <date>} element will contain the {@linkplain
* DateTimeFormatter#ISO_INSTANT formatted} instant.
* <p>
* For instance, in order to configure plain instances of XMLFormatter to omit
* the new {@code <nano>} element,
* {@code java.util.logging.XMLFormatter.useInstant = false} can be specified
* in the logging configuration.
*
* @since 1.4
*/
public class XMLFormatter extends Formatter {
private final LogManager manager = LogManager.getLogManager();
private final boolean useInstant;
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.
/**
* Creates a new instance of XMLFormatter.
*
* @implSpec
* Since JDK 9, the XMLFormatter will print out the record {@linkplain
* LogRecord#getInstant() event time} as an Instant. This instant
* has the best resolution available on the system. The {@code <date>}
* element will contain the instant as formatted by the {@link
* DateTimeFormatter#ISO_INSTANT}.
* In addition, an optional {@code <nanos>} element containing a
* nanosecond adjustment will be printed if the instant contains some
* nanoseconds below the millisecond resolution.
* <p>
* This new behavior can be turned off, and the old formatting restored,
* by specifying a property in the {@linkplain
* LogManager#getProperty(java.lang.String) logging configuration}.
* If {@code LogManager.getLogManager().getProperty(
* this.getClass().getName()+".useInstant")} is {@code "false"} or
* {@code "0"}, the old formatting will be restored.
*/
public XMLFormatter() {
useInstant = (manager == null)
|| manager.getBooleanProperty(
this.getClass().getName()+".useInstant", true);
}
// Append a two digit number.
private void a2(StringBuilder sb, int x) {
if (x < 10) {
sb.append('0');
}
sb.append(x);
}
// Append the time and date in ISO 8601 format
private void appendISO8601(StringBuilder sb, long millis) {
GregorianCalendar cal = new GregorianCalendar();
cal.setTimeInMillis(millis);
sb.append(cal.get(Calendar.YEAR));
sb.append('-');
a2(sb, cal.get(Calendar.MONTH) + 1);
sb.append('-');
a2(sb, cal.get(Calendar.DAY_OF_MONTH));
sb.append('T');
a2(sb, cal.get(Calendar.HOUR_OF_DAY));
sb.append(':');
a2(sb, cal.get(Calendar.MINUTE));
sb.append(':');
a2(sb, cal.get(Calendar.SECOND));
}
// Append to the given StringBuilder an escaped version of the
// given text string where XML special characters have been escaped.
// For a null string we append "<null>"
private void escape(StringBuilder sb, String text) {
if (text == null) {
text = "<null>";
}
for (int i = 0; i < text.length(); i++) {
char ch = text.charAt(i);
if (ch == '<') {
sb.append("<");
} else if (ch == '>') {
sb.append(">");
} else if (ch == '&') {
sb.append("&");
} else {
sb.append(ch);
}
}
}
Format the given message to XML.
This method can be overridden in a subclass. It is recommended to use the Formatter.formatMessage convenience method to localize and format the message field.
Params: - record – the log record to be formatted.
Returns: a formatted log record
/**
* Format the given message to XML.
* <p>
* This method can be overridden in a subclass.
* It is recommended to use the {@link Formatter#formatMessage}
* convenience method to localize and format the message field.
*
* @param record the log record to be formatted.
* @return a formatted log record
*/
@Override
public String format(LogRecord record) {
StringBuilder sb = new StringBuilder(500);
sb.append("<record>\n");
final Instant instant = record.getInstant();
sb.append(" <date>");
if (useInstant) {
// If useInstant is true - we will print the instant in the
// date field, using the ISO_INSTANT formatter.
DateTimeFormatter.ISO_INSTANT.formatTo(instant, sb);
} else {
// If useInstant is false - we will keep the 'old' formating
appendISO8601(sb, instant.toEpochMilli());
}
sb.append("</date>\n");
sb.append(" <millis>");
sb.append(instant.toEpochMilli());
sb.append("</millis>\n");
final int nanoAdjustment = instant.getNano() % 1000_000;
if (useInstant && nanoAdjustment != 0) {
sb.append(" <nanos>");
sb.append(nanoAdjustment);
sb.append("</nanos>\n");
}
sb.append(" <sequence>");
sb.append(record.getSequenceNumber());
sb.append("</sequence>\n");
String name = record.getLoggerName();
if (name != null) {
sb.append(" <logger>");
escape(sb, name);
sb.append("</logger>\n");
}
sb.append(" <level>");
escape(sb, record.getLevel().toString());
sb.append("</level>\n");
if (record.getSourceClassName() != null) {
sb.append(" <class>");
escape(sb, record.getSourceClassName());
sb.append("</class>\n");
}
if (record.getSourceMethodName() != null) {
sb.append(" <method>");
escape(sb, record.getSourceMethodName());
sb.append("</method>\n");
}
sb.append(" <thread>");
sb.append(record.getThreadID());
sb.append("</thread>\n");
if (record.getMessage() != null) {
// Format the message string and its accompanying parameters.
String message = formatMessage(record);
sb.append(" <message>");
escape(sb, message);
sb.append("</message>");
sb.append("\n");
}
// If the message is being localized, output the key, resource
// bundle name, and params.
ResourceBundle bundle = record.getResourceBundle();
try {
if (bundle != null && bundle.getString(record.getMessage()) != null) {
sb.append(" <key>");
escape(sb, record.getMessage());
sb.append("</key>\n");
sb.append(" <catalog>");
escape(sb, record.getResourceBundleName());
sb.append("</catalog>\n");
}
} catch (Exception ex) {
// The message is not in the catalog. Drop through.
}
Object parameters[] = record.getParameters();
// Check to see if the parameter was not a messagetext format
// or was not null or empty
if (parameters != null && parameters.length != 0
&& record.getMessage().indexOf('{') == -1 ) {
for (Object parameter : parameters) {
sb.append(" <param>");
try {
escape(sb, parameter.toString());
} catch (Exception ex) {
sb.append("???");
}
sb.append("</param>\n");
}
}
if (record.getThrown() != null) {
// Report on the state of the throwable.
Throwable th = record.getThrown();
sb.append(" <exception>\n");
sb.append(" <message>");
escape(sb, th.toString());
sb.append("</message>\n");
StackTraceElement trace[] = th.getStackTrace();
for (StackTraceElement frame : trace) {
sb.append(" <frame>\n");
sb.append(" <class>");
escape(sb, frame.getClassName());
sb.append("</class>\n");
sb.append(" <method>");
escape(sb, frame.getMethodName());
sb.append("</method>\n");
// Check for a line number.
if (frame.getLineNumber() >= 0) {
sb.append(" <line>");
sb.append(frame.getLineNumber());
sb.append("</line>\n");
}
sb.append(" </frame>\n");
}
sb.append(" </exception>\n");
}
sb.append("</record>\n");
return sb.toString();
}
Return the header string for a set of XML formatted records.
Params: - h – The target handler (can be null)
Returns: a valid XML string
/**
* Return the header string for a set of XML formatted records.
*
* @param h The target handler (can be null)
* @return a valid XML string
*/
@Override
public String getHead(Handler h) {
StringBuilder sb = new StringBuilder();
String encoding;
sb.append("<?xml version=\"1.0\"");
if (h != null) {
encoding = h.getEncoding();
} else {
encoding = null;
}
if (encoding == null) {
// Figure out the default encoding.
encoding = java.nio.charset.Charset.defaultCharset().name();
}
// Try to map the encoding name to a canonical name.
try {
Charset cs = Charset.forName(encoding);
encoding = cs.name();
} catch (Exception ex) {
// We hit problems finding a canonical name.
// Just use the raw encoding name.
}
sb.append(" encoding=\"");
sb.append(encoding);
sb.append("\"");
sb.append(" standalone=\"no\"?>\n");
sb.append("<!DOCTYPE log SYSTEM \"logger.dtd\">\n");
sb.append("<log>\n");
return sb.toString();
}
Return the tail string for a set of XML formatted records.
Params: - h – The target handler (can be null)
Returns: a valid XML string
/**
* Return the tail string for a set of XML formatted records.
*
* @param h The target handler (can be null)
* @return a valid XML string
*/
@Override
public String getTail(Handler h) {
return "</log>\n";
}
}