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.</p>
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.</p>
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).</p>
43 *
44 * <p> For example,
45 * <code><pre>
46 * if (log.isDebugEnabled()) {
47 * ... do something expensive ...
48 * log.debug(theResult);
49 * }
50 * </pre></code>
51 * </p>
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.</p>
56 *
57 * <p style="color: #E40; font-weight: bold;">Please note that this interface is identical to that found in JCL 1.1.1.</p>
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
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 public boolean isDebugEnabled();
77
78
79 /**
80 * <p> Is error logging currently enabled? </p>
81 *
82 * <p> Call this method to prevent having to perform expensive operations
83 * (for example, <code>String</code> concatenation)
84 * when the log level is more than error. </p>
85 */
86 public boolean isErrorEnabled();
87
88
89 /**
90 * <p> Is fatal logging currently enabled? </p>
91 *
92 * <p> Call this method to prevent having to perform expensive operations
93 * (for example, <code>String</code> concatenation)
94 * when the log level is more than fatal. </p>
95 */
96 public boolean isFatalEnabled();
97
98
99 /**
100 * <p> Is info logging currently enabled? </p>
101 *
102 * <p> Call this method to prevent having to perform expensive operations
103 * (for example, <code>String</code> concatenation)
104 * when the log level is more than info. </p>
105 *
106 * @return true if info enabled, false otherwise
107 */
108 public boolean isInfoEnabled();
109
110
111 /**
112 * <p> Is trace logging currently enabled? </p>
113 *
114 * <p> Call this method to prevent having to perform expensive operations
115 * (for example, <code>String</code> concatenation)
116 * when the log level is more than trace. </p>
117 *
118 * @return true if trace enabled, false otherwise
119 */
120 public boolean isTraceEnabled();
121
122
123 /**
124 * <p> Is warn logging currently enabled? </p>
125 *
126 * <p> Call this method to prevent having to perform expensive operations
127 * (for example, <code>String</code> concatenation)
128 * when the log level is more than warn. </p>
129 */
130 public boolean isWarnEnabled();
131
132
133 // -------------------------------------------------------- Logging Methods
134
135
136 /**
137 * <p> Log a message with trace log level. </p>
138 *
139 * @param message log this message
140 */
141 public void trace(Object message);
142
143
144 /**
145 * <p> Log an error with trace log level. </p>
146 *
147 * @param message log this message
148 * @param t log this cause
149 */
150 public void trace(Object message, Throwable t);
151
152
153 /**
154 * <p> Log a message with debug log level. </p>
155 *
156 * @param message log this message
157 */
158 public void debug(Object message);
159
160
161 /**
162 * <p> Log an error with debug log level. </p>
163 *
164 * @param message log this message
165 * @param t log this cause
166 */
167 public void debug(Object message, Throwable t);
168
169
170 /**
171 * <p> Log a message with info log level. </p>
172 *
173 * @param message log this message
174 */
175 public void info(Object message);
176
177
178 /**
179 * <p> Log an error with info log level. </p>
180 *
181 * @param message log this message
182 * @param t log this cause
183 */
184 public void info(Object message, Throwable t);
185
186
187 /**
188 * <p> Log a message with warn log level. </p>
189 *
190 * @param message log this message
191 */
192 public void warn(Object message);
193
194
195 /**
196 * <p> Log an error with warn log level. </p>
197 *
198 * @param message log this message
199 * @param t log this cause
200 */
201 public void warn(Object message, Throwable t);
202
203
204 /**
205 * <p> Log a message with error log level. </p>
206 *
207 * @param message log this message
208 */
209 public void error(Object message);
210
211
212 /**
213 * <p> Log an error with error log level. </p>
214 *
215 * @param message log this message
216 * @param t log this cause
217 */
218 public void error(Object message, Throwable t);
219
220
221 /**
222 * <p> Log a message with fatal log level. </p>
223 *
224 * @param message log this message
225 */
226 public void fatal(Object message);
227
228
229 /**
230 * <p> Log an error with fatal log level. </p>
231 *
232 * @param message log this message
233 * @param t log this cause
234 */
235 public void fatal(Object message, Throwable t);
236
237
238 }