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1 /*
2  * Copyright (c) 2004-2007 QOS.ch
3  * All rights reserved.
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining
6  * a copy of this software and associated documentation files (the
7  * "Software"), to deal in the Software without restriction, including
8  * without limitation the rights to use, copy, modify, merge, publish,
9  * distribute, sublicense, and/or sell copies of the Software, and to
10  * permit persons to whom the Software is furnished to do so, subject to
11  * the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be
14  * included in all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23  */
24
25 package org.slf4j;
26
27 import org.slf4j.helpers.Util;
28 import org.slf4j.impl.StaticLoggerBinder;
29  
30 /**
31  * The <code>LoggerFactory</code> is a utility class producing Loggers for
32  * various logging APIs, most notably for log4j, logback and JDK 1.4 logging.
33  * Other implementations such as {@link org.slf4j.impl.NOPLogger NOPLogger} and
34  * {@link org.slf4j.impl.SimpleLogger SimpleLogger} are also supported.
35  *
36  * <p>
37  * <code>LoggerFactory</code> is essentially a wrapper around an
38  * {@link ILoggerFactory} instance bound with <code>LoggerFactory</code> at
39  * compile time.
40  *
41  * <p>
42  * Please note that all methods in <code>LoggerFactory</code> are static.
43  *
44  * @author Ceki G&uuml;lc&uuml;
45  */
46 public final class LoggerFactory {
47
48   static ILoggerFactory loggerFactory;
49
50   static final String JavaDoc NO_STATICLOGGERBINDER_URL = "http://www.slf4j.org/codes.html#StaticLoggerBinder";
51   static final String JavaDoc NULL_LF_URL = "http://www.slf4j.org/codes.html#null_LF";
52     
53   // private constructor prevents instantiation
54 private LoggerFactory() {
55   }
56
57
58   static {
59     try {
60       loggerFactory = StaticLoggerBinder.SINGLETON.getLoggerFactory();
61     } catch(NoClassDefFoundError JavaDoc ncde) {
62       String JavaDoc msg = ncde.getMessage();
63       if(msg != null && msg.indexOf("org/slf4j/impl/StaticLoggerBinder") != -1) {
64         Util.reportFailure("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
65         Util.reportFailure("See "+NO_STATICLOGGERBINDER_URL+" for further details.");
66         
67       }
68       throw ncde;
69     } catch (Exception JavaDoc e) {
70       // we should never get here
71 Util.reportFailure("Failed to instantiate logger ["
72           + StaticLoggerBinder.SINGLETON.getLoggerFactoryClassStr() + "]", e);
73     }
74   }
75
76   /**
77    * Return a logger named according to the name parameter using the statically
78    * bound {@link ILoggerFactory} instance.
79    *
80    * @param name
81    * The name of the logger.
82    * @return logger
83    */
84   public static Logger getLogger(String JavaDoc name) {
85     if(loggerFactory == null) {
86       throw new IllegalStateException JavaDoc("Logging factory implementation cannot be null. See also "+NULL_LF_URL);
87     }
88     return loggerFactory.getLogger(name);
89   }
90
91   /**
92    * Return a logger named corresponding to the class passed as parameter, using
93    * the statically bound {@link ILoggerFactory} instance.
94    *
95    * @param clazz
96    * the returned logger will be named after clazz
97    * @return logger
98    */
99   public static Logger getLogger(Class JavaDoc clazz) {
100     if(loggerFactory == null) {
101       throw new IllegalStateException JavaDoc("Logging factory implementation cannot be null. See also "+NULL_LF_URL);
102     }
103     return loggerFactory.getLogger(clazz.getName());
104   }
105
106   /**
107    * Return the {@link ILoggerFactory} instance in use.
108    *
109    * <p>ILoggerFactory instance is bound with this class at compile
110    * time.
111    *
112    * @return the ILoggerFactory instance in use
113    */
114   public static ILoggerFactory getILoggerFactory() {
115     return loggerFactory;
116   }
117 }
118
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