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 public boolean isInfoEnabled();
107
108
109 /**
110 * <p> Is trace logging currently enabled? </p>
111 *
112 * <p> Call this method to prevent having to perform expensive operations
113 * (for example, <code>String</code> concatenation)
114 * when the log level is more than trace. </p>
115 */
116 public boolean isTraceEnabled();
117
118
119 /**
120 * <p> Is warn logging currently enabled? </p>
121 *
122 * <p> Call this method to prevent having to perform expensive operations
123 * (for example, <code>String</code> concatenation)
124 * when the log level is more than warn. </p>
125 */
126 public boolean isWarnEnabled();
127
128
129 // -------------------------------------------------------- Logging Methods
130
131
132 /**
133 * <p> Log a message with trace log level. </p>
134 *
135 * @param message log this message
136 */
137 public void trace(Object message);
138
139
140 /**
141 * <p> Log an error with trace log level. </p>
142 *
143 * @param message log this message
144 * @param t log this cause
145 */
146 public void trace(Object message, Throwable t);
147
148
149 /**
150 * <p> Log a message with debug log level. </p>
151 *
152 * @param message log this message
153 */
154 public void debug(Object message);
155
156
157 /**
158 * <p> Log an error with debug log level. </p>
159 *
160 * @param message log this message
161 * @param t log this cause
162 */
163 public void debug(Object message, Throwable t);
164
165
166 /**
167 * <p> Log a message with info log level. </p>
168 *
169 * @param message log this message
170 */
171 public void info(Object message);
172
173
174 /**
175 * <p> Log an error with info log level. </p>
176 *
177 * @param message log this message
178 * @param t log this cause
179 */
180 public void info(Object message, Throwable t);
181
182
183 /**
184 * <p> Log a message with warn log level. </p>
185 *
186 * @param message log this message
187 */
188 public void warn(Object message);
189
190
191 /**
192 * <p> Log an error with warn log level. </p>
193 *
194 * @param message log this message
195 * @param t log this cause
196 */
197 public void warn(Object message, Throwable t);
198
199
200 /**
201 * <p> Log a message with error log level. </p>
202 *
203 * @param message log this message
204 */
205 public void error(Object message);
206
207
208 /**
209 * <p> Log an error with error log level. </p>
210 *
211 * @param message log this message
212 * @param t log this cause
213 */
214 public void error(Object message, Throwable t);
215
216
217 /**
218 * <p> Log a message with fatal log level. </p>
219 *
220 * @param message log this message
221 */
222 public void fatal(Object message);
223
224
225 /**
226 * <p> Log an error with fatal log level. </p>
227 *
228 * @param message log this message
229 * @param t log this cause
230 */
231 public void fatal(Object message, Throwable t);
232
233
234 }