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
18 package org.apache.log4j.pattern;
19
20 import org.apache.log4j.spi.LoggingEvent;
21 import org.apache.log4j.spi.ThrowableInformation;
22
23
24 /**
25 * Outputs the ThrowableInformation portion of the LoggingEvent.
26 * By default, outputs the full stack trace. %throwable{none}
27 * or %throwable{0} suppresses the stack trace. %throwable{short}
28 * or %throwable{1} outputs just the first line. %throwable{n}
29 * will output n lines for a positive integer or drop the last
30 * -n lines for a negative integer.
31 *
32 * @author Paul Smith
33 *
34 */
35 public class ThrowableInformationPatternConverter
36 extends LoggingEventPatternConverter {
37
38 /**
39 * Maximum lines of stack trace to output.
40 */
41 private int maxLines = Integer.MAX_VALUE;
42
43 /**
44 * Private constructor.
45 * @param options options, may be null.
46 */
47 private ThrowableInformationPatternConverter(
48 final String[] options) {
49 super("Throwable", "throwable");
50
51 if ((options != null) && (options.length > 0)) {
52 if("none".equals(options[0])) {
53 maxLines = 0;
54 } else if("short".equals(options[0])) {
55 maxLines = 1;
56 } else {
57 try {
58 maxLines = Integer.parseInt(options[0]);
59 } catch(NumberFormatException ex) {
60 }
61 }
62 }
63 }
64
65 /**
66 * Gets an instance of the class.
67 * @param options pattern options, may be null. If first element is "short",
68 * only the first line of the throwable will be formatted.
69 * @return instance of class.
70 */
71 public static ThrowableInformationPatternConverter newInstance(
72 final String[] options) {
73 return new ThrowableInformationPatternConverter(options);
74 }
75
76 /**
77 * {@inheritDoc}
78 */
79 public void format(final LoggingEvent event, final StringBuffer toAppendTo) {
80 if (maxLines != 0) {
81 ThrowableInformation information = event.getThrowableInformation();
82
83 if (information != null) {
84 String[] stringRep = information.getThrowableStrRep();
85
86 int length = stringRep.length;
87 if (maxLines < 0) {
88 length += maxLines;
89 } else if (length > maxLines) {
90 length = maxLines;
91 }
92
93 for (int i = 0; i < length; i++) {
94 String string = stringRep[i];
95 toAppendTo.append(string).append("\n");
96 }
97 }
98 }
99 }
100
101 /**
102 * This converter obviously handles throwables.
103 * @return true.
104 */
105 public boolean handlesThrowable() {
106 return true;
107 }
108 }