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.logging.log4j.core.pattern;
19
20 import java.util.List;
21
22 import org.apache.logging.log4j.core.LogEvent;
23 import org.apache.logging.log4j.core.appender.AbstractAppender;
24 import org.apache.logging.log4j.core.config.Configuration;
25 import org.apache.logging.log4j.core.config.plugins.Plugin;
26 import org.apache.logging.log4j.core.layout.PatternLayout;
27
28 /**
29 * Max length pattern converter. Limit contained text to a maximum length.
30 * On invalid length the default value 100 is used (and an error message is logged).
31 * If max length is greater than 20, an abbreviated text will get ellipsis ("...") appended.
32 * Example usage (for email subject):
33 * {@code "%maxLen{[AppName, ${hostName}, ${web:contextPath}] %p: %c{1} - %m%notEmpty{ =>%ex{short}}}{160}"}
34 *
35 * @author Thies Wellpott
36 */
37 @Plugin(name = "maxLength", category = PatternConverter.CATEGORY)
38 @ConverterKeys({"maxLength", "maxLen"})
39 public final class MaxLengthConverter extends LogEventPatternConverter {
40
41 /**
42 * Gets an instance of the class.
43 *
44 * @param config The current Configuration.
45 * @param options pattern options, an array of two elements: pattern, max length (defaults to 100 on invalid value).
46 * @return instance of class.
47 */
48 public static MaxLengthConverter newInstance(final Configuration config, final String[] options) {
49 if (options.length != 2) {
50 LOGGER.error("Incorrect number of options on maxLength: expected 2 received {}: {}", options.length,
51 options);
52 return null;
53 }
54 if (options[0] == null) {
55 LOGGER.error("No pattern supplied on maxLength");
56 return null;
57 }
58 if (options[1] == null) {
59 LOGGER.error("No length supplied on maxLength");
60 return null;
61 }
62 final PatternParser parser = PatternLayout.createPatternParser(config);
63 final List<PatternFormatter> formatters = parser.parse(options[0]);
64 return new MaxLengthConverter(formatters, AbstractAppender.parseInt(options[1], 100));
65 }
66
67
68 private final List<PatternFormatter> formatters;
69 private final int maxLength;
70
71 /**
72 * Construct the converter.
73 *
74 * @param formatters The PatternFormatters to generate the text to manipulate.
75 * @param maxLength The max. length of the resulting string. Ellipsis ("...") is appended on shorted string, if greater than 20.
76 */
77 private MaxLengthConverter(final List<PatternFormatter> formatters, final int maxLength) {
78 super("MaxLength", "maxLength");
79 this.maxLength = maxLength;
80 this.formatters = formatters;
81 LOGGER.trace("new MaxLengthConverter with {}", maxLength);
82 }
83
84
85 @Override
86 public void format(final LogEvent event, final StringBuilder toAppendTo) {
87 final StringBuilder buf = new StringBuilder();
88 for (final PatternFormatter formatter : formatters) {
89 formatter.format(event, buf);
90 if (buf.length() > maxLength) { // stop early
91 break;
92 }
93 }
94 if (buf.length() > maxLength) {
95 buf.setLength(maxLength);
96 if (maxLength > 20) { // only append ellipses if length is not very short
97 buf.append("...");
98 }
99 }
100 toAppendTo.append(buf);
101 }
102
103 }