1/*
2 * Copyright 2001-2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package org.apache.log4j.helpers;
18
19/**
20   This class used to output log statements from within the log4j package.
21
22   <p>Log4j components cannot make log4j logging calls. However, it is
23   sometimes useful for the user to learn about what log4j is
24   doing. You can enable log4j internal logging by defining the
25   <b>log4j.configDebug</b> variable.
26
27   <p>All log4j internal debug calls go to <code>System.out</code>
28   where as internal error messages are sent to
29   <code>System.err</code>. All internal messages are prepended with
30   the string "log4j: ".
31
32   @since 0.8.2
33   @author Ceki G&uuml;lc&uuml;
34*/
35public class LogLog {
36
37    /**
38       Defining this value makes log4j print log4j-internal debug
39       statements to <code>System.out</code>.
40
41      <p> The value of this string is <b>log4j.debug</b>.
42
43      <p>Note that the search for all option names is case sensitive.  */
44    public static final String DEBUG_KEY = "log4j.debug";
45
46    /**
47       Defining this value makes log4j components print log4j-internal
48       debug statements to <code>System.out</code>.
49
50      <p> The value of this string is <b>log4j.configDebug</b>.
51
52      <p>Note that the search for all option names is case sensitive.
53
54      @deprecated Use {@link #DEBUG_KEY} instead.
55    */
56    public static final String CONFIG_DEBUG_KEY = "log4j.configDebug";
57
58    protected static boolean debugEnabled = false;
59
60    /**
61       In quietMode not even errors generate any output.
62     */
63    private static boolean quietMode = false;
64
65    private static final String PREFIX = "log4j: ";
66    private static final String ERR_PREFIX = "log4j:ERROR ";
67    private static final String WARN_PREFIX = "log4j:WARN ";
68
69    static {
70    }
71
72    /**
73       Allows to enable/disable log4j internal logging.
74     */
75    static public void setInternalDebugging(boolean enabled) {
76        debugEnabled = enabled;
77    }
78
79    /**
80       This method is used to output log4j internal debug
81       statements. Output goes to <code>System.out</code>.
82    */
83    public static void debug(String msg) {
84        if (debugEnabled && !quietMode) {
85            System.out.println(PREFIX + msg);
86        }
87    }
88
89    /**
90       This method is used to output log4j internal debug
91       statements. Output goes to <code>System.out</code>.
92    */
93    public static void debug(String msg, Throwable t) {
94        if (debugEnabled && !quietMode) {
95            System.out.println(PREFIX + msg);
96            if (t != null)
97                t.printStackTrace(System.out);
98        }
99    }
100
101    /**
102       This method is used to output log4j internal error
103       statements. There is no way to disable error statements.
104       Output goes to <code>System.err</code>.
105    */
106    public static void error(String msg) {
107        if (quietMode)
108            return;
109        System.err.println(ERR_PREFIX + msg);
110    }
111
112    /**
113       This method is used to output log4j internal error
114       statements. There is no way to disable error statements.
115       Output goes to <code>System.err</code>.
116    */
117    public static void error(String msg, Throwable t) {
118        if (quietMode)
119            return;
120
121        System.err.println(ERR_PREFIX + msg);
122        if (t != null) {
123            t.printStackTrace();
124        }
125    }
126
127    /**
128       In quite mode no LogLog generates strictly no output, not even
129       for errors.
130
131       @param quietMode A true for not
132    */
133    public static void setQuietMode(boolean quietMode) {
134        LogLog.quietMode = quietMode;
135    }
136
137    /**
138       This method is used to output log4j internal warning
139       statements. There is no way to disable warning statements.
140       Output goes to <code>System.err</code>.  */
141    public static void warn(String msg) {
142        if (quietMode)
143            return;
144
145        System.err.println(WARN_PREFIX + msg);
146    }
147
148    /**
149       This method is used to output log4j internal warnings. There is
150       no way to disable warning statements.  Output goes to
151       <code>System.err</code>.  */
152    public static void warn(String msg, Throwable t) {
153        if (quietMode)
154            return;
155
156        System.err.println(WARN_PREFIX + msg);
157        if (t != null) {
158            t.printStackTrace();
159        }
160    }
161}
162