1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18
19 package org.apache.commons.logging;
20
21 /**
22 * <p>A simple logging interface abstracting logging APIs. In order to be
23 * instantiated successfully by {@link LogFactory}, classes that implement
24 * this interface must have a constructor that takes a single String
25 * parameter representing the "name" of this Log.</p>
26 *
27 * <p> The six logging levels used by <code>Log</code> are (in order):
28 * <ol>
29 * <li>trace (the least serious)</li>
30 * <li>debug</li>
31 * <li>info</li>
32 * <li>warn</li>
33 * <li>error</li>
34 * <li>fatal (the most serious)</li>
35 * </ol>
36 * The mapping of these log levels to the concepts used by the underlying
37 * logging system is implementation dependent.
38 * The implemention should ensure, though, that this ordering behaves
39 * as expected.</p>
40 *
41 * <p>Performance is often a logging concern.
42 * By examining the appropriate property,
43 * a component can avoid expensive operations (producing information
44 * to be logged).</p>
45 *
46 * <p> For example,
47 * <code><pre>
48 * if (log.isDebugEnabled()) {
49 * ... do something expensive ...
50 * log.debug(theResult);
51 * }
52 * </pre></code>
53 * </p>
54 *
55 * <p>Configuration of the underlying logging system will generally be done
56 * external to the Logging APIs, through whatever mechanism is supported by
57 * that system.</p>
58 *
59 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
60 * @author Rod Waldhoff
61 * @version $Id: Log.java 424107 2006-07-20 23:15:42Z skitching $
62 */
63 public interface Log {
64
65
66 // ----------------------------------------------------- Logging Properties
67
68
69 /**
70 * <p> Is debug logging currently enabled? </p>
71 *
72 * <p> Call this method to prevent having to perform expensive operations
73 * (for example, <code>String</code> concatenation)
74 * when the log level is more than debug. </p>
75 *
76 * @return true if debug is enabled in the underlying logger.
77 */
78 public boolean isDebugEnabled();
79
80
81 /**
82 * <p> Is error logging currently enabled? </p>
83 *
84 * <p> Call this method to prevent having to perform expensive operations
85 * (for example, <code>String</code> concatenation)
86 * when the log level is more than error. </p>
87 *
88 * @return true if error is enabled in the underlying logger.
89 */
90 public boolean isErrorEnabled();
91
92
93 /**
94 * <p> Is fatal logging currently enabled? </p>
95 *
96 * <p> Call this method to prevent having to perform expensive operations
97 * (for example, <code>String</code> concatenation)
98 * when the log level is more than fatal. </p>
99 *
100 * @return true if fatal is enabled in the underlying logger.
101 */
102 public boolean isFatalEnabled();
103
104
105 /**
106 * <p> Is info logging currently enabled? </p>
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 info. </p>
111 *
112 * @return true if info is enabled in the underlying logger.
113 */
114 public boolean isInfoEnabled();
115
116
117 /**
118 * <p> Is trace logging currently enabled? </p>
119 *
120 * <p> Call this method to prevent having to perform expensive operations
121 * (for example, <code>String</code> concatenation)
122 * when the log level is more than trace. </p>
123 *
124 * @return true if trace is enabled in the underlying logger.
125 */
126 public boolean isTraceEnabled();
127
128
129 /**
130 * <p> Is warn logging currently enabled? </p>
131 *
132 * <p> Call this method to prevent having to perform expensive operations
133 * (for example, <code>String</code> concatenation)
134 * when the log level is more than warn. </p>
135 *
136 * @return true if warn is enabled in the underlying logger.
137 */
138 public boolean isWarnEnabled();
139
140
141 // -------------------------------------------------------- Logging Methods
142
143
144 /**
145 * <p> Log a message with trace log level. </p>
146 *
147 * @param message log this message
148 */
149 public void trace(Object message);
150
151
152 /**
153 * <p> Log an error with trace log level. </p>
154 *
155 * @param message log this message
156 * @param t log this cause
157 */
158 public void trace(Object message, Throwable t);
159
160
161 /**
162 * <p> Log a message with debug log level. </p>
163 *
164 * @param message log this message
165 */
166 public void debug(Object message);
167
168
169 /**
170 * <p> Log an error with debug log level. </p>
171 *
172 * @param message log this message
173 * @param t log this cause
174 */
175 public void debug(Object message, Throwable t);
176
177
178 /**
179 * <p> Log a message with info log level. </p>
180 *
181 * @param message log this message
182 */
183 public void info(Object message);
184
185
186 /**
187 * <p> Log an error with info log level. </p>
188 *
189 * @param message log this message
190 * @param t log this cause
191 */
192 public void info(Object message, Throwable t);
193
194
195 /**
196 * <p> Log a message with warn log level. </p>
197 *
198 * @param message log this message
199 */
200 public void warn(Object message);
201
202
203 /**
204 * <p> Log an error with warn log level. </p>
205 *
206 * @param message log this message
207 * @param t log this cause
208 */
209 public void warn(Object message, Throwable t);
210
211
212 /**
213 * <p> Log a message with error log level. </p>
214 *
215 * @param message log this message
216 */
217 public void error(Object message);
218
219
220 /**
221 * <p> Log an error with error log level. </p>
222 *
223 * @param message log this message
224 * @param t log this cause
225 */
226 public void error(Object message, Throwable t);
227
228
229 /**
230 * <p> Log a message with fatal log level. </p>
231 *
232 * @param message log this message
233 */
234 public void fatal(Object message);
235
236
237 /**
238 * <p> Log an error with fatal log level. </p>
239 *
240 * @param message log this message
241 * @param t log this cause
242 */
243 public void fatal(Object message, Throwable t);
244
245
246 }