Log4JLogger


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.impl;
19  
20  import java.io.Serializable  ;
21  import org.apache.commons.logging.Log;
22  import org.apache.log4j.Logger;
23  import org.apache.log4j.Priority;
24  import org.apache.log4j.Level;
25  
26  /**
27   * Implementation of {@link Log} that maps directly to a
28   * <strong>Logger</strong> for log4J version 1.2.
29   * <p>
30   * Initial configuration of the corresponding Logger instances should be done
31   * in the usual manner, as outlined in the Log4J documentation.
32   * <p>
33   * The reason this logger is distinct from the 1.3 logger is that in version 1.2
34   * of Log4J:
35   * <ul>
36   * <li>class Logger takes Priority parameters not Level parameters.
37   * <li>class Level extends Priority
38   * </ul>
39   * Log4J1.3 is expected to change Level so it no longer extends Priority, which is
40   * a non-binary-compatible change. The class generated by compiling this code against
41   * log4j 1.2 will therefore not run against log4j 1.3.
42   *
43   * @author <a HREF="mailto:sanders@apache.org">Scott Sanders</a>
44   * @author Rod Waldhoff
45   * @author Robert Burrell Donkin
46   * @version $Id: Log4JLogger.java 370672 2006-01-19 23:52:23Z skitching $
47   */
48  
49  public class Log4JLogger implements Log, Serializable   {
50  
51      // ------------------------------------------------------------- Attributes
52  
53      /** The fully qualified name of the Log4JLogger class. */
54      private static final String   FQCN = Log4JLogger.class.getName();
55      
56      /** Log to this logger */
57      private transient Logger logger = null;
58  
59      /** Logger name */
60      private String   name = null;
61  
62      private static Priority traceLevel;
63      
64      // ------------------------------------------------------------
65      // Static Initializer.
66      //
67      // Note that this must come after the static variable declarations
68      // otherwise initialiser expressions associated with those variables
69      // will override any settings done here.
70      //
71      // Verify that log4j is available, and that it is version 1.2.
72      // If an ExceptionInInitializerError is generated, then LogFactoryImpl
73      // will treat that as meaning that the appropriate underlying logging
74      // library is just not present - if discovery is in progress then
75      // discovery will continue.
76      // ------------------------------------------------------------
77  
78      static {
79          if (!Priority.class.isAssignableFrom(Level.class)) {
80              // nope, this is log4j 1.3, so force an ExceptionInInitializerError
81              throw new InstantiationError  ("Log4J 1.2 not available");
82          }
83          
84          // Releases of log4j1.2 >= 1.2.12 have Priority.TRACE available, earlier
85          // versions do not. If TRACE is not available, then we have to map
86          // calls to Log.trace(...) onto the DEBUG level.
87          
88          try {
89              traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
90          } catch(Exception   ex) {
91              // ok, trace not available
92              traceLevel = Priority.DEBUG;
93          }
94      }
95  
96      
97      // ------------------------------------------------------------ Constructor
98  
99      public Log4JLogger() {
100     }
101 
102 
103     /**
104      * Base constructor.
105      */
106     public Log4JLogger(String   name) {
107         this.name = name;
108         this.logger = getLogger();
109     }
110 
111     /** For use with a log4j factory.
112      */
113     public Log4JLogger(Logger logger ) {
114         this.name = logger.getName();
115         this.logger=logger;
116     }
117 
118 
119     // --------------------------------------------------------- 
120     // Implementation
121     //
122     // Note that in the methods below the Priority class is used to define
123     // levels even though the Level class is supported in 1.2. This is done
124     // so that at compile time the call definitely resolves to a call to
125     // a method that takes a Priority rather than one that takes a Level.
126     // 
127     // The Category class (and hence its subclass Logger) in version 1.2 only
128     // has methods that take Priority objects. The Category class (and hence
129     // Logger class) in version 1.3 has methods that take both Priority and
130     // Level objects. This means that if we use Level here, and compile
131     // against log4j 1.3 then calls would be bound to the versions of
132     // methods taking Level objects and then would fail to run against
133     // version 1.2 of log4j.
134     // --------------------------------------------------------- 
135 
136 
137     /**
138      * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
139      * When using a log4j version that does not support the <code>TRACE</code>
140      * level, the message will be logged at the <code>DEBUG</code> level.
141      *
142      * @param message to log
143      * @see org.apache.commons.logging.Log#trace(Object)
144      */
145     public void trace(Object   message) {
146         getLogger().log(FQCN, traceLevel, message, null );
147     }
148 
149 
150     /**
151      * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
152      * When using a log4j version that does not support the <code>TRACE</code>
153      * level, the message will be logged at the <code>DEBUG</code> level.
154      *
155      * @param message to log
156      * @param t log this cause
157      * @see org.apache.commons.logging.Log#trace(Object, Throwable)
158      */
159     public void trace(Object   message, Throwable   t) {
160         getLogger().log(FQCN, traceLevel, message, t );
161     }
162 
163 
164     /**
165      * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
166      *
167      * @param message to log
168      * @see org.apache.commons.logging.Log#debug(Object)
169      */
170     public void debug(Object   message) {
171         getLogger().log(FQCN, Priority.DEBUG, message, null );
172     }
173 
174     /**
175      * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
176      *
177      * @param message to log
178      * @param t log this cause
179      * @see org.apache.commons.logging.Log#debug(Object, Throwable)
180      */
181     public void debug(Object   message, Throwable   t) {
182         getLogger().log(FQCN, Priority.DEBUG, message, t );
183     }
184 
185 
186     /**
187      * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
188      *
189      * @param message to log
190      * @see org.apache.commons.logging.Log#info(Object)
191      */
192     public void info(Object   message) {
193         getLogger().log(FQCN, Priority.INFO, message, null );
194     }
195 
196 
197     /**
198      * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
199      *
200      * @param message to log
201      * @param t log this cause
202      * @see org.apache.commons.logging.Log#info(Object, Throwable)
203      */
204     public void info(Object   message, Throwable   t) {
205         getLogger().log(FQCN, Priority.INFO, message, t );
206     }
207 
208 
209     /**
210      * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
211      *
212      * @param message to log
213      * @see org.apache.commons.logging.Log#warn(Object)
214      */
215     public void warn(Object   message) {
216         getLogger().log(FQCN, Priority.WARN, message, null );
217     }
218 
219 
220     /**
221      * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
222      *
223      * @param message to log
224      * @param t log this cause
225      * @see org.apache.commons.logging.Log#warn(Object, Throwable)
226      */
227     public void warn(Object   message, Throwable   t) {
228         getLogger().log(FQCN, Priority.WARN, message, t );
229     }
230 
231 
232     /**
233      * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
234      *
235      * @param message to log
236      * @see org.apache.commons.logging.Log#error(Object)
237      */
238     public void error(Object   message) {
239         getLogger().log(FQCN, Priority.ERROR, message, null );
240     }
241 
242 
243     /**
244      * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
245      *
246      * @param message to log
247      * @param t log this cause
248      * @see org.apache.commons.logging.Log#error(Object, Throwable)
249      */
250     public void error(Object   message, Throwable   t) {
251         getLogger().log(FQCN, Priority.ERROR, message, t );
252     }
253 
254 
255     /**
256      * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
257      *
258      * @param message to log
259      * @see org.apache.commons.logging.Log#fatal(Object)
260      */
261     public void fatal(Object   message) {
262         getLogger().log(FQCN, Priority.FATAL, message, null );
263     }
264 
265 
266     /**
267      * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
268      *
269      * @param message to log
270      * @param t log this cause
271      * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
272      */
273     public void fatal(Object   message, Throwable   t) {
274         getLogger().log(FQCN, Priority.FATAL, message, t );
275     }
276 
277 
278     /**
279      * Return the native Logger instance we are using.
280      */
281     public Logger getLogger() {
282         if (logger == null) {
283             logger = Logger.getLogger(name);
284         }
285         return (this.logger);
286     }
287 
288 
289     /**
290      * Check whether the Log4j Logger used is enabled for <code>DEBUG</code> priority.
291      */
292     public boolean isDebugEnabled() {
293         return getLogger().isDebugEnabled();
294     }
295 
296 
297      /**
298      * Check whether the Log4j Logger used is enabled for <code>ERROR</code> priority.
299      */
300     public boolean isErrorEnabled() {
301         return getLogger().isEnabledFor(Priority.ERROR);
302     }
303 
304 
305     /**
306      * Check whether the Log4j Logger used is enabled for <code>FATAL</code> priority.
307      */
308     public boolean isFatalEnabled() {
309         return getLogger().isEnabledFor(Priority.FATAL);
310     }
311 
312 
313     /**
314      * Check whether the Log4j Logger used is enabled for <code>INFO</code> priority.
315      */
316     public boolean isInfoEnabled() {
317         return getLogger().isInfoEnabled();
318     }
319 
320 
321     /**
322      * Check whether the Log4j Logger used is enabled for <code>TRACE</code> priority.
323      * When using a log4j version that does not support the TRACE level, this call
324      * will report whether <code>DEBUG</code> is enabled or not.
325      */
326     public boolean isTraceEnabled() {
327         return getLogger().isEnabledFor(traceLevel);
328     }
329 
330     /**
331      * Check whether the Log4j Logger used is enabled for <code>WARN</code> priority.
332      */
333     public boolean isWarnEnabled() {
334         return getLogger().isEnabledFor(Priority.WARN);
335     }
336 }
337
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