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
17 package org.apache.commons.logging;
18
19 /**
20 * <p>A simple logging interface abstracting logging APIs. In order to be
21 * instantiated successfully by {@link LogFactory}, classes that implement
22 * this interface must have a constructor that takes a single String
23 * parameter representing the "name" of this Log.
24 *
25 * <p> The six logging levels used by <code>Log</code> are (in order):
26 * <ol>
27 * <li>trace (the least serious)</li>
28 * <li>debug</li>
29 * <li>info</li>
30 * <li>warn</li>
31 * <li>error</li>
32 * <li>fatal (the most serious)</li>
33 * </ol>
34 * The mapping of these log levels to the concepts used by the underlying
35 * logging system is implementation dependent.
36 * The implementation should ensure, though, that this ordering behaves
37 * as expected.
38 *
39 * <p>Performance is often a logging concern.
40 * By examining the appropriate property,
41 * a component can avoid expensive operations (producing information
42 * to be logged).
43 *
44 * <p> For example,
45 * <pre>
46 * if (log.isDebugEnabled()) {
47 * ... do something expensive ...
48 * log.debug(theResult);
49 * }
50 * </pre>
51 *
52 *
53 * <p>Configuration of the underlying logging system will generally be done
54 * external to the Logging APIs, through whatever mechanism is supported by
55 * that system.
56 *
57 * <p style="color: #E40; font-weight: bold;">Please note that this interface is identical to that found in JCL 1.1.1.
58 *
59 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
60 * @author Rod Waldhoff
61 * @version $Id: Log.java,v 1.19 2004/06/06 21:16:04 rdonkin Exp $
62 */
63 public interface Log {
64
65 // ----------------------------------------------------- Logging Properties
66
67 /**
68 * <p> Is debug logging currently enabled?
69 *
70 * <p> Call this method to prevent having to perform expensive operations
71 * (for example, <code>String</code> concatenation)
72 * when the log level is more than debug.
73 */
74 public boolean isDebugEnabled();
75
76 /**
77 * <p> Is error logging currently enabled?
78 *
79 * <p> Call this method to prevent having to perform expensive operations
80 * (for example, <code>String</code> concatenation)
81 * when the log level is more than error.
82 */
83 public boolean isErrorEnabled();
84
85 /**
86 * <p> Is fatal logging currently enabled?
87 *
88 * <p> Call this method to prevent having to perform expensive operations
89 * (for example, <code>String</code> concatenation)
90 * when the log level is more than fatal.
91 */
92 public boolean isFatalEnabled();
93
94 /**
95 * <p> Is info logging currently enabled?
96 *
97 * <p> Call this method to prevent having to perform expensive operations
98 * (for example, <code>String</code> concatenation)
99 * when the log level is more than info.
100 *
101 * @return true if info enabled, false otherwise
102 */
103 public boolean isInfoEnabled();
104
105 /**
106 * <p> Is trace logging currently enabled?
107 *
108 * <p> Call this method to prevent having to perform expensive operations
109 * (for example, <code>String</code> concatenation)
110 * when the log level is more than trace.
111 *
112 * @return true if trace enabled, false otherwise
113 */
114 public boolean isTraceEnabled();
115
116 /**
117 * <p> Is warn logging currently enabled?
118 *
119 * <p> Call this method to prevent having to perform expensive operations
120 * (for example, <code>String</code> concatenation)
121 * when the log level is more than warn.
122 */
123 public boolean isWarnEnabled();
124
125 // -------------------------------------------------------- Logging Methods
126
127 /**
128 * <p> Log a message with trace log level.
129 *
130 * @param message log this message
131 */
132 public void trace(Object message);
133
134 /**
135 * <p> Log an error with trace log level.
136 *
137 * @param message log this message
138 * @param t log this cause
139 */
140 public void trace(Object message, Throwable t);
141
142 /**
143 * <p> Log a message with debug log level.
144 *
145 * @param message log this message
146 */
147 public void debug(Object message);
148
149 /**
150 * <p> Log an error with debug log level.
151 *
152 * @param message log this message
153 * @param t log this cause
154 */
155 public void debug(Object message, Throwable t);
156
157 /**
158 * <p> Log a message with info log level.
159 *
160 * @param message log this message
161 */
162 public void info(Object message);
163
164 /**
165 * <p> Log an error with info log level.
166 *
167 * @param message log this message
168 * @param t log this cause
169 */
170 public void info(Object message, Throwable t);
171
172 /**
173 * <p> Log a message with warn log level.
174 *
175 * @param message log this message
176 */
177 public void warn(Object message);
178
179 /**
180 * <p> Log an error with warn log level.
181 *
182 * @param message log this message
183 * @param t log this cause
184 */
185 public void warn(Object message, Throwable t);
186
187 /**
188 * <p> Log a message with error log level.
189 *
190 * @param message log this message
191 */
192 public void error(Object message);
193
194 /**
195 * <p> Log an error with error log level.
196 *
197 * @param message log this message
198 * @param t log this cause
199 */
200 public void error(Object message, Throwable t);
201
202 /**
203 * <p> Log a message with fatal log level.
204 *
205 * @param message log this message
206 */
207 public void fatal(Object message);
208
209 /**
210 * <p> Log an error with fatal log level.
211 *
212 * @param message log this message
213 * @param t log this cause
214 */
215 public void fatal(Object message, Throwable t);
216
217 }