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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.io.*;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Objects;

/**

 * Stream based logging {@code Handler}.

 * <p>

 * This is primarily intended as a base class or support class to

 * be used in implementing other logging {@code Handlers}.

 * <p>

 * {@code LogRecords} are published to a given {@code java.io.OutputStream}.

 * <p>

 * <b>Configuration:</b>

 * By default each {@code StreamHandler} is initialized using the following

 * {@code LogManager} configuration properties where {@code <handler-name>}

 * refers to the fully-qualified class name of the handler.

 * If properties are not defined

 * (or have invalid values) then the specified default values are used.

 * <ul>

 * <li>   &lt;handler-name&gt;.level

 *        specifies the default level for the {@code Handler}

 *        (defaults to {@code Level.INFO}). </li>

 * <li>   &lt;handler-name&gt;.filter

 *        specifies the name of a {@code Filter} class to use

 *         (defaults to no {@code Filter}). </li>

 * <li>   &lt;handler-name&gt;.formatter

 *        specifies the name of a {@code Formatter} class to use

 *        (defaults to {@code java.util.logging.SimpleFormatter}). </li>

 * <li>   &lt;handler-name&gt;.encoding

 *        the name of the character set encoding to use (defaults to

 *        the default platform encoding). </li>

 * </ul>

 * <p>

 * For example, the properties for {@code StreamHandler} would be:

 * <ul>

 * <li>   java.util.logging.StreamHandler.level=INFO </li>

 * <li>   java.util.logging.StreamHandler.formatter=java.util.logging.SimpleFormatter </li>

 * </ul>

 * <p>

 * For a custom handler, e.g. com.foo.MyHandler, the properties would be:

 * <ul>

 * <li>   com.foo.MyHandler.level=INFO </li>

 * <li>   com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>

 * </ul>

 *

 * @since 1.4

 */

public class StreamHandler extends Handler {

    private OutputStream output;

    private boolean doneHeader;

    private volatile Writer writer;

    /**

     * Create a {@code StreamHandler}, with no current output stream.

     */

    public StreamHandler() {

        // configure with specific defaults for StreamHandler

        super(Level.INFO, new SimpleFormatter(), null);

    }

    /**

     * Create a {@code StreamHandler} with a given {@code Formatter}

     * and output stream.

     *

     * @param out         the target output stream

     * @param formatter   Formatter to be used to format output

     */

    public StreamHandler(OutputStream out, Formatter formatter) {

        // configure with default level but use specified formatter

        super(Level.INFO, null, Objects.requireNonNull(formatter));

        setOutputStreamPrivileged(out);

    }

    /**

     * @see Handler#Handler(Level, Formatter, Formatter)

     */

    StreamHandler(Level defaultLevel,

                  Formatter defaultFormatter,

                  Formatter specifiedFormatter) {

        super(defaultLevel, defaultFormatter, specifiedFormatter);

    }

    /**

     * Change the output stream.

     * <P>

     * If there is a current output stream then the {@code Formatter}'s

     * tail string is written and the stream is flushed and closed.

     * Then the output stream is replaced with the new output stream.

     *

     * @param out   New output stream.  May not be null.

     * @exception  SecurityException  if a security manager exists and if

     *             the caller does not have {@code LoggingPermission("control")}.

     */

    protected synchronized void setOutputStream(OutputStream out) throws SecurityException {

        if (out == null) {

            throw new NullPointerException();

        }

        flushAndClose();

        output = out;

        doneHeader = false;

        String encoding = getEncoding();

        if (encoding == null) {

            writer = new OutputStreamWriter(output);

        } else {

            try {

                writer = new OutputStreamWriter(output, encoding);

            } catch (UnsupportedEncodingException ex) {

                // This shouldn't happen.  The setEncoding method

                // should have validated that the encoding is OK.

                throw new Error("Unexpected exception " + ex);

            }

        }

    }

    /**

     * Set (or change) the character encoding used by this {@code Handler}.

     * <p>

     * The encoding should be set before any {@code LogRecords} are written

     * to the {@code Handler}.

     *

     * @param encoding  The name of a supported character encoding.

     *        May be null, to indicate the default platform encoding.

     * @exception  SecurityException  if a security manager exists and if

     *             the caller does not have {@code LoggingPermission("control")}.

     * @exception  UnsupportedEncodingException if the named encoding is

     *          not supported.

     */

    @Override

    public synchronized void setEncoding(String encoding)

                        throws SecurityException, java.io.UnsupportedEncodingException {

        super.setEncoding(encoding);

        if (output == null) {

            return;

        }

        // Replace the current writer with a writer for the new encoding.

        flush();

        if (encoding == null) {

            writer = new OutputStreamWriter(output);

        } else {

            writer = new OutputStreamWriter(output, encoding);

        }

    }

    /**

     * Format and publish a {@code LogRecord}.

     * <p>

     * The {@code StreamHandler} first checks if there is an {@code OutputStream}

     * and if the given {@code LogRecord} has at least the required log level.

     * If not it silently returns.  If so, it calls any associated

     * {@code Filter} to check if the record should be published.  If so,

     * it calls its {@code Formatter} to format the record and then writes

     * the result to the current output stream.

     * <p>

     * If this is the first {@code LogRecord} to be written to a given

     * {@code OutputStream}, the {@code Formatter}'s "head" string is

     * written to the stream before the {@code LogRecord} is written.

     *

     * @param  record  description of the log event. A null record is

     *                 silently ignored and is not published

     */

    @Override

    public synchronized void publish(LogRecord record) {

        if (!isLoggable(record)) {

            return;

        }

        String msg;

        try {

            msg = getFormatter().format(record);

        } catch (Exception ex) {

            // We don't want to throw an exception here, but we

            // report the exception to any registered ErrorManager.

            reportError(null, ex, ErrorManager.FORMAT_FAILURE);

            return;

        }

        try {

            if (!doneHeader) {

                writer.write(getFormatter().getHead(this));

                doneHeader = true;

            }

            writer.write(msg);

        } catch (Exception ex) {

            // We don't want to throw an exception here, but we

            // report the exception to any registered ErrorManager.

            reportError(null, ex, ErrorManager.WRITE_FAILURE);

        }

    }

    /**

     * Check if this {@code Handler} would actually log a given {@code LogRecord}.

     * <p>

     * This method checks if the {@code LogRecord} has an appropriate level and

     * whether it satisfies any {@code Filter}.  It will also return false if

     * no output stream has been assigned yet or the LogRecord is null.

     *

     * @param record  a {@code LogRecord}

     * @return true if the {@code LogRecord} would be logged.

     *

     */

    @Override

    public boolean isLoggable(LogRecord record) {

        if (writer == null || record == null) {

            return false;

        }

        return super.isLoggable(record);

    }

    /**

     * Flush any buffered messages.

     */

    @Override

    public synchronized void flush() {

        if (writer != null) {

            try {

                writer.flush();

            } catch (Exception ex) {

                // We don't want to throw an exception here, but we

                // report the exception to any registered ErrorManager.

                reportError(null, ex, ErrorManager.FLUSH_FAILURE);

            }

        }

    }

    private synchronized void flushAndClose() throws SecurityException {

        checkPermission();

        if (writer != null) {

            try {

                if (!doneHeader) {

                    writer.write(getFormatter().getHead(this));

                    doneHeader = true;

                }

                writer.write(getFormatter().getTail(this));

                writer.flush();

                writer.close();

            } catch (Exception ex) {

                // We don't want to throw an exception here, but we

                // report the exception to any registered ErrorManager.

                reportError(null, ex, ErrorManager.CLOSE_FAILURE);

            }

            writer = null;

            output = null;

        }

    }

    /**

     * Close the current output stream.

     * <p>

     * The {@code Formatter}'s "tail" string is written to the stream before it

     * is closed.  In addition, if the {@code Formatter}'s "head" string has not

     * yet been written to the stream, it will be written before the

     * "tail" string.

     *

     * @exception  SecurityException  if a security manager exists and if

     *             the caller does not have LoggingPermission("control").

     */

    @Override

    public synchronized void close() throws SecurityException {

        flushAndClose();

    }

    // Package-private support for setting OutputStream

    // with elevated privilege.

    final void setOutputStreamPrivileged(final OutputStream out) {

        AccessController.doPrivileged(new PrivilegedAction<Void>() {

            @Override

            public Void run() {

                setOutputStream(out);

                return null;

            }

        }, null, LogManager.controlPermission);

    }

}