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jlechner |
/* Handler.java -- a class for publishing log messages
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Copyright (C) 2002, 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util.logging;
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import java.io.UnsupportedEncodingException;
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/**
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* A <code>Handler</code> publishes <code>LogRecords</code> to
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* a sink, for example a file, the console or a network socket.
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* There are different subclasses of <code>Handler</code>
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* to deal with different kinds of sinks.
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*
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* <p>FIXME: Are handlers thread-safe, or is the assumption that only
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* loggers are, and a handler can belong only to one single logger? If
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* the latter, should we enforce it? (Spec not clear). In any
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* case, it needs documentation.
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*
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* @author Sascha Brawer (brawer@acm.org)
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*/
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public abstract class Handler
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{
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Formatter formatter;
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Filter filter;
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Level level;
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ErrorManager errorManager;
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String encoding;
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/**
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* Constructs a Handler with a logging severity level of
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* <code>Level.ALL</code>, no formatter, no filter, and
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* an instance of <code>ErrorManager</code> managing errors.
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*
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* <p><strong>Specification Note:</strong> The specification of the
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* Java<sup>TM</sup> Logging API does not mention which character
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* encoding is to be used by freshly constructed Handlers. The GNU
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* implementation uses the default platform encoding, but other
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* Java implementations might behave differently.
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*
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* <p><strong>Specification Note:</strong> While a freshly constructed
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* Handler is required to have <em>no filter</em> according to the
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* specification, <code>null</code> is not a valid parameter for
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* <code>Handler.setFormatter</code>. Therefore, the following
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* code will throw a <code>java.lang.NullPointerException</code>:
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*
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* <p><pre>Handler h = new MyConcreteSubclassOfHandler();
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h.setFormatter(h.getFormatter());</pre>
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*
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* It seems strange that a freshly constructed Handler is not
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* supposed to provide a Formatter, but this is what the specification
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* says.
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*/
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protected Handler()
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{
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level = Level.ALL;
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}
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/**
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* Publishes a <code>LogRecord</code> to an appropriate sink,
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* provided the record passes all tests for being loggable. The
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* <code>Handler</code> will localize the message of the log
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* record and substitute any message parameters.
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*
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* <p>Most applications do not need to call this method directly.
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* Instead, they will use use a {@link Logger}, which will
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* create LogRecords and distribute them to registered handlers.
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*
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* <p>In case of an I/O failure, the <code>ErrorManager</code>
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* of this <code>Handler</code> will be informed, but the caller
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* of this method will not receive an exception.
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*
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* @param record the log event to be published.
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*/
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public abstract void publish(LogRecord record);
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/**
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* Forces any data that may have been buffered to the underlying
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* output device.
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*
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* <p>In case of an I/O failure, the <code>ErrorManager</code>
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* of this <code>Handler</code> will be informed, but the caller
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* of this method will not receive an exception.
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*/
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public abstract void flush();
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/**
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* Closes this <code>Handler</code> after having flushed
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* the buffers. As soon as <code>close</code> has been called,
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* a <code>Handler</code> should not be used anymore. Attempts
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* to publish log records, to flush buffers, or to modify the
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* <code>Handler</code> in any other way may throw runtime
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* exceptions after calling <code>close</code>.
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*
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* <p>In case of an I/O failure, the <code>ErrorManager</code>
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* of this <code>Handler</code> will be informed, but the caller
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* of this method will not receive an exception.
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*
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* @throws SecurityException if a security manager exists and
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* the caller is not granted the permission to control
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* the logging infrastructure.
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*/
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public abstract void close()
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throws SecurityException;
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/**
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* Returns the <code>Formatter</code> which will be used to
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* localize the text of log messages and to substitute
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* message parameters. A <code>Handler</code> is encouraged,
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* but not required to actually use an assigned
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* <code>Formatter</code>.
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*
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* @return the <code>Formatter</code> being used, or
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* <code>null</code> if this <code>Handler</code>
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* does not use formatters and no formatter has
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* ever been set by calling <code>setFormatter</code>.
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*/
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public Formatter getFormatter()
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{
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return formatter;
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}
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/**
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* Sets the <code>Formatter</code> which will be used to
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* localize the text of log messages and to substitute
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* message parameters. A <code>Handler</code> is encouraged,
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* but not required to actually use an assigned
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* <code>Formatter</code>.
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*
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* @param formatter the new <code>Formatter</code> to use.
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*
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* @throws SecurityException if a security manager exists and
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* the caller is not granted the permission to control
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* the logging infrastructure.
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*
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* @throws NullPointerException if <code>formatter</code> is
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* <code>null</code>.
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*/
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public void setFormatter(Formatter formatter)
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throws SecurityException
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{
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LogManager.getLogManager().checkAccess();
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/* Throws a NullPointerException if formatter is null. */
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formatter.getClass();
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this.formatter = formatter;
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}
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/**
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* Returns the character encoding which this handler uses for publishing
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* log records.
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*
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* @return the name of a character encoding, or <code>null</code>
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* for the default platform encoding.
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*/
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public String getEncoding()
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{
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return encoding;
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}
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/**
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* Sets the character encoding which this handler uses for publishing
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* log records. The encoding of a <code>Handler</code> must be
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* set before any log records have been published.
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*
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* @param encoding the name of a character encoding, or <code>null</code>
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* for the default encoding.
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*
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* @exception SecurityException if a security manager exists and
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* the caller is not granted the permission to control
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* the logging infrastructure.
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*
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*/
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public void setEncoding(String encoding)
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throws SecurityException, UnsupportedEncodingException
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{
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/* Should any developer ever change this implementation, they are
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* advised to have a look at StreamHandler.setEncoding(String),
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* which overrides this method without calling super.setEncoding.
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*/
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LogManager.getLogManager().checkAccess();
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/* Simple check for supported encodings. This is more expensive
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* than it could be, but this method is overwritten by StreamHandler
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* anyway.
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*/
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if (encoding != null)
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new String(new byte[0], encoding);
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this.encoding = encoding;
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}
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/**
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* Returns the <code>Filter</code> that currently controls which
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* log records are being published by this <code>Handler</code>.
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*
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* @return the currently active <code>Filter</code>, or
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* <code>null</code> if no filter has been associated.
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* In the latter case, log records are filtered purely
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* based on their severity level.
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*/
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public Filter getFilter()
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{
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return filter;
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}
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/**
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* Sets the <code>Filter</code> for controlling which
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* log records will be published by this <code>Handler</code>.
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*
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* @param filter the <code>Filter</code> to use, or
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* <code>null</code> to filter log records purely based
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* on their severity level.
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*/
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public void setFilter(Filter filter)
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throws SecurityException
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{
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LogManager.getLogManager().checkAccess();
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this.filter = filter;
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}
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/**
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* Returns the <code>ErrorManager</code> that currently deals
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* with errors originating from this Handler.
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*
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* @exception SecurityException if a security manager exists and
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* the caller is not granted the permission to control
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* the logging infrastructure.
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*/
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public ErrorManager getErrorManager()
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{
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LogManager.getLogManager().checkAccess();
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/* Developers wanting to change the subsequent code should
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* have a look at Handler.reportError -- it also can create
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* an ErrorManager, but does so without checking permissions
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* to control the logging infrastructure.
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*/
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if (errorManager == null)
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errorManager = new ErrorManager();
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return errorManager;
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}
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public void setErrorManager(ErrorManager manager)
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{
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LogManager.getLogManager().checkAccess();
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/* Make sure manager is not null. */
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manager.getClass();
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this.errorManager = manager;
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}
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protected void reportError(String message, Exception ex, int code)
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{
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if (errorManager == null)
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errorManager = new ErrorManager();
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errorManager.error(message, ex, code);
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}
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/**
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* Returns the severity level threshold for this <code>Handler</code>
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* All log records with a lower severity level will be discarded;
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* a log record of the same or a higher level will be published
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* unless an installed <code>Filter</code> decides to discard it.
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*
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* @return the severity level below which all log messages
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* will be discarded.
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*/
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public Level getLevel()
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{
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return level;
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}
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/**
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* Sets the severity level threshold for this <code>Handler</code>.
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* All log records with a lower severity level will be discarded;
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* a log record of the same or a higher level will be published
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* unless an installed <code>Filter</code> decides to discard it.
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*
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* @param level the severity level below which all log messages
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* will be discarded.
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*
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* @exception SecurityException if a security manager exists and
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* the caller is not granted the permission to control
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* the logging infrastructure.
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*
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* @exception NullPointerException if <code>level</code> is
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* <code>null</code>.
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*/
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public void setLevel(Level level)
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{
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LogManager.getLogManager().checkAccess();
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/* Throw NullPointerException if level is null. */
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level.getClass();
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this.level = level;
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}
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/**
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* Checks whether a <code>LogRecord</code> would be logged
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* if it was passed to this <code>Handler</code> for publication.
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*
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* <p>The <code>Handler</code> implementation considers a record as
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* loggable if its level is greater than or equal to the severity
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* level threshold. In a second step, if a {@link Filter} has
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* been installed, its {@link Filter#isLoggable(LogRecord) isLoggable}
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* method is invoked. Subclasses of <code>Handler</code> can override
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* this method to impose their own constraints.
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*
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* @param record the <code>LogRecord</code> to be checked.
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*
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|
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* @return <code>true</code> if <code>record</code> would
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|
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* be published by {@link #publish(LogRecord) publish},
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* <code>false</code> if it would be discarded.
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*
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* @see #setLevel(Level)
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* @see #setFilter(Filter)
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* @see Filter#isLoggable(LogRecord)
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*
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|
|
* @throws NullPointerException if <code>record</code>
|
374 |
|
|
* is <code>null</code>.
|
375 |
|
|
*/
|
376 |
|
|
public boolean isLoggable(LogRecord record)
|
377 |
|
|
{
|
378 |
|
|
if (record.getLevel().intValue() < level.intValue())
|
379 |
|
|
return false;
|
380 |
|
|
|
381 |
|
|
if (filter != null)
|
382 |
|
|
return filter.isLoggable(record);
|
383 |
|
|
else
|
384 |
|
|
return true;
|
385 |
|
|
}
|
386 |
|
|
}
|