1 /**
2 * Copyright (c) 2004-2011 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.ext;
26
27 import org.apache.commons.lang.text.StrLookup;
28 import org.slf4j.MDC;
29
30 /**
31 * This class can be used with the Commons Lang StrSubstitutor to replace
32 * tokens that occur in Strings with their values in the MDC.
33 *
34 * @author Ralph Goers
35 */
36 public class MDCStrLookup extends StrLookup {
37 /**
38 * Looks up up a value in the MDC.
39 *
40 * @param key the key to be looked up, may be null
41 * @return the matching value, null if no match
42 */
43 public String lookup(String key) {
44 if (key == null) {
45 return null;
46 }
47 return MDC.get(key);
48 }
49 }