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 package org.apache.commons.logging;
19
20 /**
21 * 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.
25 * <p>
26 * The six logging levels used by {@code Log} 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.
39 * <p>
40 * 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).
44 * <p>
45 * For example,
46 * <pre>
47 * if (log.isDebugEnabled()) {
48 * ... do something expensive ...
49 * log.debug(theResult);
50 * }
51 * </pre>
52 * <p>
53 * 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 public interface Log {
58
59 /**
60 * Logs a message with debug log level.
61 *
62 * @param message log this message
63 */
64 void debug(Object message);
65
66 /**
67 * Logs an error with debug log level.
68 *
69 * @param message log this message
70 * @param t log this cause
71 */
72 void debug(Object message, Throwable t);
73
74 /**
75 * Logs a message with error log level.
76 *
77 * @param message log this message
78 */
79 void error(Object message);
80
81 /**
82 * Logs an error with error log level.
83 *
84 * @param message log this message
85 * @param t log this cause
86 */
87 void error(Object message, Throwable t);
88
89 /**
90 * Logs a message with fatal log level.
91 *
92 * @param message log this message
93 */
94 void fatal(Object message);
95
96 /**
97 * Logs an error with fatal log level.
98 *
99 * @param message log this message
100 * @param t log this cause
101 */
102 void fatal(Object message, Throwable t);
103
104 /**
105 * Logs a message with info log level.
106 *
107 * @param message log this message
108 */
109 void info(Object message);
110
111 /**
112 * Logs an error with info log level.
113 *
114 * @param message log this message
115 * @param t log this cause
116 */
117 void info(Object message, Throwable t);
118
119 /**
120 * Is debug logging currently enabled?
121 * <p>
122 * Call this method to prevent having to perform expensive operations
123 * (for example, {@code String} concatenation)
124 * when the log level is more than debug.
125 *
126 * @return true if debug is enabled in the underlying logger.
127 */
128 boolean isDebugEnabled();
129
130 /**
131 * Is error logging currently enabled?
132 * <p>
133 * Call this method to prevent having to perform expensive operations
134 * (for example, {@code String} concatenation)
135 * when the log level is more than error.
136 *
137 * @return true if error is enabled in the underlying logger.
138 */
139 boolean isErrorEnabled();
140
141 /**
142 * Is fatal logging currently enabled?
143 * <p>
144 * Call this method to prevent having to perform expensive operations
145 * (for example, {@code String} concatenation)
146 * when the log level is more than fatal.
147 *
148 * @return true if fatal is enabled in the underlying logger.
149 */
150 boolean isFatalEnabled();
151
152 /**
153 * Is info logging currently enabled?
154 * <p>
155 * Call this method to prevent having to perform expensive operations
156 * (for example, {@code String} concatenation)
157 * when the log level is more than info.
158 *
159 * @return true if info is enabled in the underlying logger.
160 */
161 boolean isInfoEnabled();
162
163 /**
164 * Is trace logging currently enabled?
165 * <p>
166 * Call this method to prevent having to perform expensive operations
167 * (for example, {@code String} concatenation)
168 * when the log level is more than trace.
169 *
170 * @return true if trace is enabled in the underlying logger.
171 */
172 boolean isTraceEnabled();
173
174 /**
175 * Is warn logging currently enabled?
176 * <p>
177 * Call this method to prevent having to perform expensive operations
178 * (for example, {@code String} concatenation)
179 * when the log level is more than warn.
180 *
181 * @return true if warn is enabled in the underlying logger.
182 */
183 boolean isWarnEnabled();
184
185 /**
186 * Logs a message with trace log level.
187 *
188 * @param message log this message
189 */
190 void trace(Object message);
191
192 /**
193 * Logs an error with trace log level.
194 *
195 * @param message log this message
196 * @param t log this cause
197 */
198 void trace(Object message, Throwable t);
199
200 /**
201 * Logs a message with warn log level.
202 *
203 * @param message log this message
204 */
205 void warn(Object message);
206
207 /**
208 * Logs an error with warn log level.
209 *
210 * @param message log this message
211 * @param t log this cause
212 */
213 void warn(Object message, Throwable t);
214 }