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 package org.apache.log4j;
18
19 import java.util.Hashtable;
20
21 import org.slf4j.helpers.Util;
22
23 /**
24 * This class is a factory that creates and maintains org.apache.log4j.Loggers
25 * wrapping org.slf4j.Loggers.
26 *
27 * It keeps a hashtable of all created org.apache.log4j.Logger instances so that
28 * all newly created instances are not dulpicates of existing loggers.
29 *
30 * @author Sébastien Pennec
31 */
32 class Log4jLoggerFactory {
33
34 // String, Logger
35 private static Hashtable log4jLoggers = new Hashtable();
36
37 private static final String LOG4J_DELEGATION_LOOP_URL = "http://www.slf4j.org/codes.html#log4jDelegationLoop";
38
39 // check for delegation loops
40 static {
41 try {
42 Class.forName("org.slf4j.impl.Log4jLoggerFactory");
43 String part1 = "Detected both log4j-over-slf4j.jar AND slf4j-log4j12.jar on the class path, preempting StackOverflowError. ";
44 String part2 = "See also " + LOG4J_DELEGATION_LOOP_URL
45 + " for more details.";
46
47 Util.report(part1);
48 Util.report(part2);
49 throw new IllegalStateException(part1 + part2);
50 } catch (ClassNotFoundException e) {
51 // this is the good case
52 }
53 }
54
55 public static synchronized Logger getLogger(String name) {
56 if (log4jLoggers.containsKey(name)) {
57 return (org.apache.log4j.Logger) log4jLoggers.get(name);
58 } else {
59 Logger log4jLogger = new Logger(name);
60
61 log4jLoggers.put(name, log4jLogger);
62 return log4jLogger;
63 }
64 }
65
66 }