/*
* Copyright (c) 2000, 2006, 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
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*/
package java.util.logging;
import java.io.UnsupportedEncodingException;
/**
* A <tt>Handler</tt> object takes log messages from a <tt>Logger</tt> and
* exports them. It might for example, write them to a console
* or write them to a file, or send them to a network logging service,
* or forward them to an OS log, or whatever.
* <p>
* A <tt>Handler</tt> can be disabled by doing a <tt>setLevel(Level.OFF)</tt>
* and can be re-enabled by doing a <tt>setLevel</tt> with an appropriate level.
* <p>
* <tt>Handler</tt> classes typically use <tt>LogManager</tt> properties to set
* default values for the <tt>Handler</tt>'s <tt>Filter</tt>, <tt>Formatter</tt>,
* and <tt>Level</tt>. See the specific documentation for each concrete
* <tt>Handler</tt> class.
*
*
* @since 1.4
*/
public abstract class Handler {
private static final int offValue = Level.OFF.intValue();
private LogManager manager = LogManager.getLogManager();
private Filter filter;
private Formatter formatter;
private Level logLevel = Level.ALL;
private ErrorManager errorManager = new ErrorManager();
private String encoding;
// Package private support for security checking. When sealed
// is true, we access check updates to the class.
boolean sealed = true;
/**
* Default constructor. The resulting <tt>Handler</tt> has a log
* level of <tt>Level.ALL</tt>, no <tt>Formatter</tt>, and no
* <tt>Filter</tt>. A default <tt>ErrorManager</tt> instance is installed
* as the <tt>ErrorManager</tt>.
*/
protected Handler() {
}
/**
* Publish a <tt>LogRecord</tt>.
* <p>
* The logging request was made initially to a <tt>Logger</tt> object,
* which initialized the <tt>LogRecord</tt> and forwarded it here.
* <p>
* The <tt>Handler</tt> is responsible for formatting the message, when and
* if necessary. The formatting should include localization.
*
* @param record description of the log event. A null record is
* silently ignored and is not published
*/
public abstract void publish(LogRecord record);
/**
* Flush any buffered output.
*/
public abstract void flush();
/**
* Close the <tt>Handler</tt> and free all associated resources.
* <p>
* The close method will perform a <tt>flush</tt> and then close the
* <tt>Handler</tt>. After close has been called this <tt>Handler</tt>
* should no longer be used. Method calls may either be silently
* ignored or may throw runtime exceptions.
*
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public abstract void close() throws SecurityException;
/**
* Set a <tt>Formatter</tt>. This <tt>Formatter</tt> will be used
* to format <tt>LogRecords</tt> for this <tt>Handler</tt>.
* <p>
* Some <tt>Handlers</tt> may not use <tt>Formatters</tt>, in
* which case the <tt>Formatter</tt> will be remembered, but not used.
* <p>
* @param newFormatter the <tt>Formatter</tt> to use (may not be null)
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public void setFormatter(Formatter newFormatter) throws SecurityException {
checkAccess();
// Check for a null pointer:
newFormatter.getClass();
formatter = newFormatter;
}
/**
* Return the <tt>Formatter</tt> for this <tt>Handler</tt>.
* @return the <tt>Formatter</tt> (may be null).
*/
public Formatter getFormatter() {
return formatter;
}
/**
* Set the character encoding used by this <tt>Handler</tt>.
* <p>
* The encoding should be set before any <tt>LogRecords</tt> are written
* to the <tt>Handler</tt>.
*
* @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 <tt>LoggingPermission("control")</tt>.
* @exception UnsupportedEncodingException if the named encoding is
* not supported.
*/
public void setEncoding(String encoding)
throws SecurityException, java.io.UnsupportedEncodingException {
checkAccess();
if (encoding != null) {
try {
if(!java.nio.charset.Charset.isSupported(encoding)) {
throw new UnsupportedEncodingException(encoding);
}
} catch (java.nio.charset.IllegalCharsetNameException e) {
throw new UnsupportedEncodingException(encoding);
}
}
this.encoding = encoding;
}
/**
* Return the character encoding for this <tt>Handler</tt>.
*
* @return The encoding name. May be null, which indicates the
* default encoding should be used.
*/
public String getEncoding() {
return encoding;
}
/**
* Set a <tt>Filter</tt> to control output on this <tt>Handler</tt>.
* <P>
* For each call of <tt>publish</tt> the <tt>Handler</tt> will call
* this <tt>Filter</tt> (if it is non-null) to check if the
* <tt>LogRecord</tt> should be published or discarded.
*
* @param newFilter a <tt>Filter</tt> object (may be null)
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public void setFilter(Filter newFilter) throws SecurityException {
checkAccess();
filter = newFilter;
}
/**
* Get the current <tt>Filter</tt> for this <tt>Handler</tt>.
*
* @return a <tt>Filter</tt> object (may be null)
*/
public Filter getFilter() {
return filter;
}
/**
* Define an ErrorManager for this Handler.
* <p>
* The ErrorManager's "error" method will be invoked if any
* errors occur while using this Handler.
*
* @param em the new ErrorManager
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public void setErrorManager(ErrorManager em) {
checkAccess();
if (em == null) {
throw new NullPointerException();
}
errorManager = em;
}
/**
* Retrieves the ErrorManager for this Handler.
*
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public ErrorManager getErrorManager() {
checkAccess();
return errorManager;
}
/**
* Protected convenience method to report an error to this Handler's
* ErrorManager. Note that this method retrieves and uses the ErrorManager
* without doing a security check. It can therefore be used in
* environments where the caller may be non-privileged.
*
* @param msg a descriptive string (may be null)
* @param ex an exception (may be null)
* @param code an error code defined in ErrorManager
*/
protected void reportError(String msg, Exception ex, int code) {
try {
errorManager.error(msg, ex, code);
} catch (Exception ex2) {
System.err.println("Handler.reportError caught:");
ex2.printStackTrace();
}
}
/**
* Set the log level specifying which message levels will be
* logged by this <tt>Handler</tt>. Message levels lower than this
* value will be discarded.
* <p>
* The intention is to allow developers to turn on voluminous
* logging, but to limit the messages that are sent to certain
* <tt>Handlers</tt>.
*
* @param newLevel the new value for the log level
* @exception SecurityException if a security manager exists and if
* the caller does not have <tt>LoggingPermission("control")</tt>.
*/
public synchronized void setLevel(Level newLevel) throws SecurityException {
if (newLevel == null) {
throw new NullPointerException();
}
checkAccess();
logLevel = newLevel;
}
/**
* Get the log level specifying which messages will be
* logged by this <tt>Handler</tt>. Message levels lower
* than this level will be discarded.
* @return the level of messages being logged.
*/
public synchronized Level getLevel() {
return logLevel;
}
/**
* Check if this <tt>Handler</tt> would actually log a given <tt>LogRecord</tt>.
* <p>
* This method checks if the <tt>LogRecord</tt> has an appropriate
* <tt>Level</tt> and whether it satisfies any <tt>Filter</tt>. It also
* may make other <tt>Handler</tt> specific checks that might prevent a
* handler from logging the <tt>LogRecord</tt>. It will return false if
* the <tt>LogRecord</tt> is Null.
* <p>
* @param record a <tt>LogRecord</tt>
* @return true if the <tt>LogRecord</tt> would be logged.
*
*/
public boolean isLoggable(LogRecord record) {
int levelValue = getLevel().intValue();
if (record.getLevel().intValue() < levelValue || levelValue == offValue) {
return false;
}
Filter filter = getFilter();
if (filter == null) {
return true;
}
return filter.isLoggable(record);
}
// Package-private support method for security checks.
// If "sealed" is true, we check that the caller has
// appropriate security privileges to update Handler
// state and if not throw a SecurityException.
void checkAccess() throws SecurityException {
if (sealed) {
manager.checkAccess();
}
}
}