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 * 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

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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.

 * <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";

    }

}