/*
* Copyright (c) 2000, 2013, 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.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> <handler-name>.level
* specifies the default level for the {@code Handler}
* (defaults to {@code Level.INFO}). </li>
* <li> <handler-name>.filter
* specifies the name of a {@code Filter} class to use
* (defaults to no {@code Filter}). </li>
* <li> <handler-name>.formatter
* specifies the name of a {@code Formatter} class to use
* (defaults to {@code java.util.logging.SimpleFormatter}). </li>
* <li> <handler-name>.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);
}
}