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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 implemention 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 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
59 * @author Rod Waldhoff
60 * @version $Id: Log.java 381838 2006-02-28 23:57:11Z skitching $
61 */
62 public interface Log {
63
64
65
66
67
68 /***
69 * <p> Is debug logging currently enabled? </p>
70 *
71 * <p> Call this method to prevent having to perform expensive operations
72 * (for example, <code>String</code> concatenation)
73 * when the log level is more than debug. </p>
74 *
75 * @return true if debug is enabled in the underlying logger.
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 * @return true if error is enabled in the underlying logger.
88 */
89 public boolean isErrorEnabled();
90
91
92 /***
93 * <p> Is fatal logging currently enabled? </p>
94 *
95 * <p> Call this method to prevent having to perform expensive operations
96 * (for example, <code>String</code> concatenation)
97 * when the log level is more than fatal. </p>
98 *
99 * @return true if fatal is enabled in the underlying logger.
100 */
101 public boolean isFatalEnabled();
102
103
104 /***
105 * <p> Is info logging currently enabled? </p>
106 *
107 * <p> Call this method to prevent having to perform expensive operations
108 * (for example, <code>String</code> concatenation)
109 * when the log level is more than info. </p>
110 *
111 * @return true if info is enabled in the underlying logger.
112 */
113 public boolean isInfoEnabled();
114
115
116 /***
117 * <p> Is trace logging currently enabled? </p>
118 *
119 * <p> Call this method to prevent having to perform expensive operations
120 * (for example, <code>String</code> concatenation)
121 * when the log level is more than trace. </p>
122 *
123 * @return true if trace is enabled in the underlying logger.
124 */
125 public boolean isTraceEnabled();
126
127
128 /***
129 * <p> Is warn logging currently enabled? </p>
130 *
131 * <p> Call this method to prevent having to perform expensive operations
132 * (for example, <code>String</code> concatenation)
133 * when the log level is more than warn. </p>
134 *
135 * @return true if warn is enabled in the underlying logger.
136 */
137 public boolean isWarnEnabled();
138
139
140
141
142
143 /***
144 * <p> Log a message with trace log level. </p>
145 *
146 * @param message log this message
147 */
148 public void trace(Object message);
149
150
151 /***
152 * <p> Log an error with trace log level. </p>
153 *
154 * @param message log this message
155 * @param t log this cause
156 */
157 public void trace(Object message, Throwable t);
158
159
160 /***
161 * <p> Log a message with debug log level. </p>
162 *
163 * @param message log this message
164 */
165 public void debug(Object message);
166
167
168 /***
169 * <p> Log an error with debug log level. </p>
170 *
171 * @param message log this message
172 * @param t log this cause
173 */
174 public void debug(Object message, Throwable t);
175
176
177 /***
178 * <p> Log a message with info log level. </p>
179 *
180 * @param message log this message
181 */
182 public void info(Object message);
183
184
185 /***
186 * <p> Log an error with info log level. </p>
187 *
188 * @param message log this message
189 * @param t log this cause
190 */
191 public void info(Object message, Throwable t);
192
193
194 /***
195 * <p> Log a message with warn log level. </p>
196 *
197 * @param message log this message
198 */
199 public void warn(Object message);
200
201
202 /***
203 * <p> Log an error with warn log level. </p>
204 *
205 * @param message log this message
206 * @param t log this cause
207 */
208 public void warn(Object message, Throwable t);
209
210
211 /***
212 * <p> Log a message with error log level. </p>
213 *
214 * @param message log this message
215 */
216 public void error(Object message);
217
218
219 /***
220 * <p> Log an error with error log level. </p>
221 *
222 * @param message log this message
223 * @param t log this cause
224 */
225 public void error(Object message, Throwable t);
226
227
228 /***
229 * <p> Log a message with fatal log level. </p>
230 *
231 * @param message log this message
232 */
233 public void fatal(Object message);
234
235
236 /***
237 * <p> Log an error with fatal log level. </p>
238 *
239 * @param message log this message
240 * @param t log this cause
241 */
242 public void fatal(Object message, Throwable t);
243
244
245 }