1 /*********************************************************************
2 *
3 * Copyright (C) 2003 Andrew Khan
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ***************************************************************************/
19
20 package common;
21
22 import java.security.AccessControlException;
23
24 /**
25 * Abstract wrapper class for the logging interface of choice.
26 * The methods declared here are the same as those for the log4j
27 */
28 public abstract class Logger
29 {
30 /**
31 * The singleton logger
32 */
33 private static Logger logger = null;
34
35 /**
36 * Factory method to return the logger
37 */
38 public static final Logger getLogger(Class cl)
39 {
40 if (logger == null)
41 {
42 initializeLogger();
43 }
44
45 return logger.getLoggerImpl(cl);
46 }
47
48 /**
49 * Initializes the logger in a thread safe manner
50 */
51 private synchronized static void initializeLogger()
52 {
53 if (logger != null)
54 {
55 return;
56 }
57
58 String loggerName = common.log.LoggerName.NAME;
59
60 try
61 {
62 // First see if there was anything defined at run time
63 loggerName = System.getProperty("logger");
64
65 if (loggerName == null)
66 {
67 // Get the logger name from the compiled in logger
68 loggerName = common.log.LoggerName.NAME;
69 }
70
71 logger = (Logger) Class.forName(loggerName).newInstance();
72 }
73 catch(IllegalAccessException e)
74 {
75 logger = new common.log.SimpleLogger();
76 logger.warn("Could not instantiate logger " + loggerName +
77 " using default");
78 }
79 catch(InstantiationException e)
80 {
81 logger = new common.log.SimpleLogger();
82 logger.warn("Could not instantiate logger " + loggerName +
83 " using default");
84 }
85 catch (AccessControlException e)
86 {
87 logger = new common.log.SimpleLogger();
88 logger.warn("Could not instantiate logger " + loggerName +
89 " using default");
90 }
91 catch(ClassNotFoundException e)
92 {
93 logger = new common.log.SimpleLogger();
94 logger.warn("Could not instantiate logger " + loggerName +
95 " using default");
96 }
97 }
98
99 /**
100 * Constructor
101 */
102 protected Logger()
103 {
104 }
105
106 /**
107 * Log a debug message
108 */
109 public abstract void debug(Object message);
110
111 /**
112 * Log a debug message and exception
113 */
114 public abstract void debug(Object message, Throwable t);
115
116 /**
117 * Log an error message
118 */
119 public abstract void error(Object message);
120
121 /**
122 * Log an error message object and exception
123 */
124 public abstract void error(Object message, Throwable t);
125
126 /**
127 * Log a fatal message
128 */
129 public abstract void fatal(Object message);
130
131 /**
132 * Log a fatal message and exception
133 */
134 public abstract void fatal(Object message, Throwable t);
135
136 /**
137 * Log an information message
138 */
139 public abstract void info(Object message);
140
141 /**
142 * Logs an information message and an exception
143 */
144 public abstract void info(Object message, Throwable t);
145
146 /**
147 * Log a warning message object
148 */
149 public abstract void warn(Object message);
150
151 /**
152 * Log a warning message with exception
153 */
154 public abstract void warn(Object message, Throwable t);
155
156 /**
157 * Accessor to the logger implementation
158 */
159 protected abstract Logger getLoggerImpl(Class cl);
160
161 /**
162 * Empty implementation of the suppressWarnings. Subclasses may
163 * or may not override this method. This method is included
164 * primarily for backwards support of the jxl.nowarnings property, and
165 * is used only by the SimpleLogger
166 *
167 * @param w suppression flag
168 */
169 public void setSuppressWarnings(boolean w)
170 {
171 // default implementation does nothing
172 }
173 }
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