Java tutorial
/* * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ 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. * <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. * * @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. * <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. * * @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. * * @param h The target handler (can be null) * @return a valid XML string */ @Override public String getTail(Handler h) { return "</log>\n"; } }