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
18 package org.apache.commons.logging;
19
20 /**
21 * <p>A simple logging interface abstracting logging APIs. In order to be
22 * instantiated successfully by {@link LogFactory}, classes that implement
23 * this interface must have a constructor that takes a single String
24 * parameter representing the "name" of this Log.</p>
25 *
26 * <p> The six logging levels used by <code>Log</code> are (in order):
27 * <ol>
28 * <li>trace (the least serious)</li>
29 * <li>debug</li>
30 * <li>info</li>
31 * <li>warn</li>
32 * <li>error</li>
33 * <li>fatal (the most serious)</li>
34 * </ol>
35 * The mapping of these log levels to the concepts used by the underlying
36 * logging system is implementation dependent.
37 * The implementation should ensure, though, that this ordering behaves
38 * as expected.</p>
39 *
40 * <p>Performance is often a logging concern.
41 * By examining the appropriate property,
42 * a component can avoid expensive operations (producing information
43 * to be logged).</p>
44 *
45 * <p> For example,
46 * <code><pre>
47 * if (log.isDebugEnabled()) {
48 * ... do something expensive ...
49 * log.debug(theResult);
50 * }
51 * </pre></code>
52 * </p>
53 *
54 * <p>Configuration of the underlying logging system will generally be done
55 * external to the Logging APIs, through whatever mechanism is supported by
56 * that system.</p>
57 *
58 * <p style="color: #E40; font-weight: bold;">Please note that this interface is identical to that found in JCL 1.1.1.</p>
59 *
60 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
61 * @author Rod Waldhoff
62 * @version $Id: Log.java,v 1.19 2004/06/06 21:16:04 rdonkin Exp $
63 */
64 public interface Log {
65
66
67 // ----------------------------------------------------- Logging Properties
68
69
70 /**
71 * <p> Is debug logging currently enabled? </p>
72 *
73 * <p> Call this method to prevent having to perform expensive operations
74 * (for example, <code>String</code> concatenation)
75 * when the log level is more than debug. </p>
76 */
77 public boolean isDebugEnabled();
78
79
80 /**
81 * <p> Is error logging currently enabled? </p>
82 *
83 * <p> Call this method to prevent having to perform expensive operations
84 * (for example, <code>String</code> concatenation)
85 * when the log level is more than error. </p>
86 */
87 public boolean isErrorEnabled();
88
89
90 /**
91 * <p> Is fatal logging currently enabled? </p>
92 *
93 * <p> Call this method to prevent having to perform expensive operations
94 * (for example, <code>String</code> concatenation)
95 * when the log level is more than fatal. </p>
96 */
97 public boolean isFatalEnabled();
98
99
100 /**
101 * <p> Is info logging currently enabled? </p>
102 *
103 * <p> Call this method to prevent having to perform expensive operations
104 * (for example, <code>String</code> concatenation)
105 * when the log level is more than info. </p>
106 */
107 public boolean isInfoEnabled();
108
109
110 /**
111 * <p> Is trace logging currently enabled? </p>
112 *
113 * <p> Call this method to prevent having to perform expensive operations
114 * (for example, <code>String</code> concatenation)
115 * when the log level is more than trace. </p>
116 */
117 public boolean isTraceEnabled();
118
119
120 /**
121 * <p> Is warn logging currently enabled? </p>
122 *
123 * <p> Call this method to prevent having to perform expensive operations
124 * (for example, <code>String</code> concatenation)
125 * when the log level is more than warn. </p>
126 */
127 public boolean isWarnEnabled();
128
129
130 // -------------------------------------------------------- Logging Methods
131
132
133 /**
134 * <p> Log a message with trace log level. </p>
135 *
136 * @param message log this message
137 */
138 public void trace(Object message);
139
140
141 /**
142 * <p> Log an error with trace log level. </p>
143 *
144 * @param message log this message
145 * @param t log this cause
146 */
147 public void trace(Object message, Throwable t);
148
149
150 /**
151 * <p> Log a message with debug log level. </p>
152 *
153 * @param message log this message
154 */
155 public void debug(Object message);
156
157
158 /**
159 * <p> Log an error with debug log level. </p>
160 *
161 * @param message log this message
162 * @param t log this cause
163 */
164 public void debug(Object message, Throwable t);
165
166
167 /**
168 * <p> Log a message with info log level. </p>
169 *
170 * @param message log this message
171 */
172 public void info(Object message);
173
174
175 /**
176 * <p> Log an error with info log level. </p>
177 *
178 * @param message log this message
179 * @param t log this cause
180 */
181 public void info(Object message, Throwable t);
182
183
184 /**
185 * <p> Log a message with warn log level. </p>
186 *
187 * @param message log this message
188 */
189 public void warn(Object message);
190
191
192 /**
193 * <p> Log an error with warn log level. </p>
194 *
195 * @param message log this message
196 * @param t log this cause
197 */
198 public void warn(Object message, Throwable t);
199
200
201 /**
202 * <p> Log a message with error log level. </p>
203 *
204 * @param message log this message
205 */
206 public void error(Object message);
207
208
209 /**
210 * <p> Log an error with error log level. </p>
211 *
212 * @param message log this message
213 * @param t log this cause
214 */
215 public void error(Object message, Throwable t);
216
217
218 /**
219 * <p> Log a message with fatal log level. </p>
220 *
221 * @param message log this message
222 */
223 public void fatal(Object message);
224
225
226 /**
227 * <p> Log an error with fatal log level. </p>
228 *
229 * @param message log this message
230 * @param t log this cause
231 */
232 public void fatal(Object message, Throwable t);
233
234
235 }