ConsoleHandler.java revision 4ff539dbc5a809ef3eacbe2d9f2b97f640b7e9cf 
1/*
2 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26
27package java.util.logging;
28
29/**
30 * This <tt>Handler</tt> publishes log records to <tt>System.err</tt>.
31 * By default the <tt>SimpleFormatter</tt> is used to generate brief summaries.
32 * <p>
33 * <b>Configuration:</b>
34 * By default each <tt>ConsoleHandler</tt> is initialized using the following
35 * <tt>LogManager</tt> configuration properties where {@code <handler-name>}
36 * refers to the fully-qualified class name of the handler.
37 * If properties are not defined
38 * (or have invalid values) then the specified default values are used.
39 * <ul>
40 * <li>   &lt;handler-name&gt;.level
41 *        specifies the default level for the <tt>Handler</tt>
42 *        (defaults to <tt>Level.INFO</tt>). </li>
43 * <li>   &lt;handler-name&gt;.filter
44 *        specifies the name of a <tt>Filter</tt> class to use
45 *        (defaults to no <tt>Filter</tt>). </li>
46 * <li>   &lt;handler-name&gt;.formatter
47 *        specifies the name of a <tt>Formatter</tt> class to use
48 *        (defaults to <tt>java.util.logging.SimpleFormatter</tt>). </li>
49 * <li>   &lt;handler-name&gt;.encoding
50 *        the name of the character set encoding to use (defaults to
51 *        the default platform encoding). </li>
52 * </ul>
53 * <p>
54 * For example, the properties for {@code ConsoleHandler} would be:
55 * <ul>
56 * <li>   java.util.logging.ConsoleHandler.level=INFO </li>
57 * <li>   java.util.logging.ConsoleHandler.formatter=java.util.logging.SimpleFormatter </li>
58 * </ul>
59 * <p>
60 * For a custom handler, e.g. com.foo.MyHandler, the properties would be:
61 * <ul>
62 * <li>   com.foo.MyHandler.level=INFO </li>
63 * <li>   com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>
64 * </ul>
65 * <p>
66 * @since 1.4
67 */
68public class ConsoleHandler extends StreamHandler {
69    // Private method to configure a ConsoleHandler from LogManager
70    // properties and/or default values as specified in the class
71    // javadoc.
72    private void configure() {
73        LogManager manager = LogManager.getLogManager();
74        String cname = getClass().getName();
75
76        setLevel(manager.getLevelProperty(cname +".level", Level.INFO));
77        setFilter(manager.getFilterProperty(cname +".filter", null));
78        setFormatter(manager.getFormatterProperty(cname +".formatter", new SimpleFormatter()));
79        try {
80            setEncoding(manager.getStringProperty(cname +".encoding", null));
81        } catch (Exception ex) {
82            try {
83                setEncoding(null);
84            } catch (Exception ex2) {
85                // doing a setEncoding with null should always work.
86                // assert false;
87            }
88        }
89    }
90
91    /**
92     * Create a <tt>ConsoleHandler</tt> for <tt>System.err</tt>.
93     * <p>
94     * The <tt>ConsoleHandler</tt> is configured based on
95     * <tt>LogManager</tt> properties (or their default values).
96     *
97     */
98    public ConsoleHandler() {
99        sealed = false;
100        configure();
101        setOutputStream(System.err);
102        sealed = true;
103    }
104
105    /**
106     * Publish a <tt>LogRecord</tt>.
107     * <p>
108     * The logging request was made initially to a <tt>Logger</tt> object,
109     * which initialized the <tt>LogRecord</tt> and forwarded it here.
110     * <p>
111     * @param  record  description of the log event. A null record is
112     *                 silently ignored and is not published
113     */
114    @Override
115    public void publish(LogRecord record) {
116        super.publish(record);
117        flush();
118    }
119
120    /**
121     * Override <tt>StreamHandler.close</tt> to do a flush but not
122     * to close the output stream.  That is, we do <b>not</b>
123     * close <tt>System.err</tt>.
124     */
125    @Override
126    public void close() {
127        flush();
128    }
129}
130