1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.log4j.helpers;
18
19 import org.apache.log4j.spi.LoggingEvent;
20 import org.apache.log4j.pattern.LogEvent;
21
22 import java.lang.reflect.Method;
23 import java.lang.reflect.InvocationTargetException;
24 import java.util.Set;
25 import java.io.ByteArrayOutputStream;
26 import java.io.ObjectOutputStream;
27 import java.io.ByteArrayInputStream;
28 import java.io.ObjectInputStream;
29
30
31 public final class MDCKeySetExtractor {
32 private final Method getKeySetMethod;
33 public static final MDCKeySetExtractor INSTANCE =
34 new MDCKeySetExtractor();
35
36
37 private MDCKeySetExtractor() {
38 //
39 // log4j 1.2.15 and later will have method to get names
40 // of all keys in MDC
41 //
42 Method getMethod = null;
43
44 try {
45 getMethod = LoggingEvent.class.getMethod(
46 "getPropertyKeySet", null);
47 } catch(Exception ex) {
48 getMethod = null;
49 }
50 getKeySetMethod = getMethod;
51
52 }
53
54 public Set getPropertyKeySet(final LoggingEvent event) throws Exception {
55 //
56 // MDC keys are not visible prior to log4j 1.2.15
57 //
58 Set keySet = null;
59 if (getKeySetMethod != null) {
60 keySet = (Set) getKeySetMethod.invoke(event, null);
61 } else {
62 //
63 // for 1.2.14 and earlier could serialize and
64 // extract MDC content
65 ByteArrayOutputStream outBytes = new ByteArrayOutputStream();
66 ObjectOutputStream os = new ObjectOutputStream(outBytes);
67 os.writeObject(event);
68 os.close();
69
70 byte[] raw = outBytes.toByteArray();
71 //
72 // bytes 6 and 7 should be the length of the original classname
73 // should be the same as our substitute class name
74 final String subClassName = LogEvent.class.getName();
75 if (raw[6] == 0 || raw[7] == subClassName.length()) {
76 //
77 // manipulate stream to use our class name
78 //
79 for (int i = 0; i < subClassName.length(); i++) {
80 raw[8 + i] = (byte) subClassName.charAt(i);
81 }
82 ByteArrayInputStream inBytes = new ByteArrayInputStream(raw);
83 ObjectInputStream is = new ObjectInputStream(inBytes);
84 Object cracked = is.readObject();
85 if (cracked instanceof LogEvent) {
86 keySet = ((LogEvent) cracked).getPropertyKeySet();
87 }
88 is.close();
89 }
90 }
91 return keySet;
92 }
93 }