001    /* SocketHandler.java -- a class for publishing log messages to network sockets
002       Copyright (C) 2002 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.util.logging;
040    
041    
042    /**
043     * A <code>SocketHandler</code> publishes log records to
044     * a TCP/IP socket.
045     *
046     * <p><strong>Configuration:</strong> Values of the subsequent
047     * <code>LogManager</code> properties are taken into consideration
048     * when a <code>SocketHandler</code> is initialized.
049     * If a property is not defined, or if it has an invalid
050     * value, a default is taken without an exception being thrown.
051     *
052     * <ul>
053     *
054     * <li><code>java.util.SocketHandler.level</code> - specifies
055     *     the initial severity level threshold. Default value:
056     *     <code>Level.ALL</code>.</li>
057     *
058     * <li><code>java.util.SocketHandler.filter</code> - specifies
059     *     the name of a Filter class. Default value: No Filter.</li>
060     *
061     * <li><code>java.util.SocketHandler.formatter</code> - specifies
062     *     the name of a Formatter class. Default value:
063     *     <code>java.util.logging.XMLFormatter</code>.</li>
064     *
065     * <li><code>java.util.SocketHandler.encoding</code> - specifies
066     *     the name of the character encoding. Default value:
067     *     the default platform encoding.</li>
068     *
069     * <li><code>java.util.SocketHandler.host</code> - specifies
070     *     the name of the host to which records are published.
071     *     There is no default value for this property; if it is
072     *     not set, the SocketHandler constructor will throw
073     *     an exception.</li>
074     *
075     * <li><code>java.util.SocketHandler.port</code> - specifies
076     *     the TCP/IP port to which records are published.
077     *     There is no default value for this property; if it is
078     *     not set, the SocketHandler constructor will throw
079     *     an exception.</li>
080     *
081     * </ul>
082     *
083     * @author Sascha Brawer (brawer@acm.org)
084     */
085    public class SocketHandler
086      extends StreamHandler
087    {
088      /**
089       * Constructs a <code>SocketHandler</code> that publishes log
090       * records to a TCP/IP socket.  Tthe initial configuration is
091       * determined by the <code>LogManager</code> properties described
092       * above.
093       *
094       * @throws java.io.IOException if the connection to the specified
095       *         network host and port cannot be established.
096       *
097       * @throws java.lang.IllegalArgumentException if either the
098       *         <code>java.util.logging.SocketHandler.host</code>
099       *         or <code>java.util.logging.SocketHandler.port</code>
100       *         LogManager properties is not defined, or specifies
101       *         an invalid value.
102       */
103      public SocketHandler()
104        throws java.io.IOException
105      {
106        this(LogManager.getLogManager().getProperty("java.util.logging.SocketHandler.host"),
107             getPortNumber());
108      }
109    
110        
111      /**
112       * Constructs a <code>SocketHandler</code> that publishes log
113       * records to a TCP/IP socket.  With the exception of the internet
114       * host and port, the initial configuration is determined by the
115       * <code>LogManager</code> properties described above.
116       *
117       * @param host the Internet host to which log records will be
118       *        forwarded.
119       *
120       * @param port the port at the host which will accept a request
121       *        for a TCP/IP connection.
122       *
123       * @throws java.io.IOException if the connection to the specified
124       *         network host and port cannot be established.
125       *
126       * @throws java.lang.IllegalArgumentException if either
127       *         <code>host</code> or <code>port</code> specify
128       *         an invalid value.
129       */
130      public SocketHandler(String host, int port)
131        throws java.io.IOException
132      {
133        super(createSocket(host, port),
134              "java.util.logging.SocketHandler",
135              /* default level */ Level.ALL,
136              /* formatter */ null,
137              /* default formatter */ XMLFormatter.class);
138      }
139    
140    
141      /**
142       * Retrieves the port number from the java.util.logging.SocketHandler.port
143       * LogManager property.
144       *
145       * @throws IllegalArgumentException if the property is not defined or
146       *         does not specify an integer value.
147       */
148      private static int getPortNumber()
149      {
150        try {
151          return Integer.parseInt(LogManager.getLogManager().getProperty("java.util.logging.SocketHandler.port"));
152        } catch (Exception ex) {
153          throw new IllegalArgumentException();
154        }
155      }
156    
157    
158      /**
159       * Creates an OutputStream for publishing log records to an Internet
160       * host and port.  This private method is a helper for use by the
161       * constructor of SocketHandler.
162       *
163       * @param host the Internet host to which log records will be
164       *        forwarded.
165       *
166       * @param port the port at the host which will accept a request
167       *        for a TCP/IP connection.
168       *
169       * @throws java.io.IOException if the connection to the specified
170       *         network host and port cannot be established.
171       *
172       * @throws java.lang.IllegalArgumentException if either
173       *         <code>host</code> or <code>port</code> specify
174       *         an invalid value.
175       */
176      private static java.io.OutputStream createSocket(String host, int port)
177        throws java.io.IOException, java.lang.IllegalArgumentException
178      {
179        java.net.Socket  socket;
180    
181        if ((host == null) || (port < 1))
182          throw new IllegalArgumentException();
183    
184        socket = new java.net.Socket(host, port);
185    
186        socket.shutdownInput();
187    
188        /* The architecture of the logging framework provides replaceable
189         * formatters.  Because these formatters perform their task by
190         * returning one single String for each LogRecord to be formatted,
191         * there is no need to buffer.
192         */
193        socket.setTcpNoDelay(true);
194    
195        return socket.getOutputStream();
196      }
197    
198    
199      /**
200       * Publishes a <code>LogRecord</code> to the network socket,
201       * provided the record passes all tests for being loggable.
202       * In addition, all data that may have been buffered will
203       * be forced to the network stream.
204       *
205       * <p>Most applications do not need to call this method directly.
206       * Instead, they will use a {@link Logger} instance, which will
207       * create LogRecords and distribute them to registered handlers.
208       *
209       * <p>In case of an I/O failure, the <code>ErrorManager</code>
210       * of this <code>SocketHandler</code> will be informed, but the caller
211       * of this method will not receive an exception.
212       *
213       * @param record the log event to be published.
214       */
215      public void publish(LogRecord record)
216      {
217        super.publish(record);
218        flush();
219      }
220    }
221