/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.juli;
import java.util.logging.LogManager;
import java.util.logging.LogRecord;
/**
* Provides the same information as the one line format but using JSON formatting. All the information of the LogRecord
* is included as a one line JSON document, including the full stack trace of the associated exception if any.
* <p>
* The LogRecord is mapped as attributes:
* <ul>
* <li>time: the log record timestamp, with the default format as {@code yyyy-MM-dd'T'HH:mm:ss.SSSX}</li>
* <li>level: the log level</li>
* <li>thread: the current on which the log occurred</li>
* <li>class: the class from which the log originated</li>
* <li>method: the method from which the log originated</li>
* <li>message: the log message</li>
* <li>throwable: the full stack trace from an exception, if present, represented as an array of string (the message
* first, then one string per stack trace element prefixed by a whitespace, then moving on to the cause exception if
* any)</li>
* </ul>
*/
public class JsonFormatter extends OneLineFormatter {
private static final String DEFAULT_TIME_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSX";
public JsonFormatter() {
String timeFormat = LogManager.getLogManager().getProperty(JsonFormatter.class.getName() + ".timeFormat");
if (timeFormat == null) {
timeFormat = DEFAULT_TIME_FORMAT;
}
setTimeFormat(timeFormat);
}
@Override
public String format(LogRecord record) {
StringBuilder sb = new StringBuilder();
sb.append('{');
// Timestamp
sb.append("\"time\": \"");
addTimestamp(sb, record.getMillis());
sb.append("\", ");
// Severity
sb.append("\"level\": \"");
sb.append(record.getLevel().getLocalizedName());
sb.append("\", ");
// Thread
sb.append("\"thread\": \"");
sb.append(resolveThreadName(record));
sb.append("\", ");
// Source
sb.append("\"class\": \"");
sb.append(record.getSourceClassName());
sb.append("\", ");
sb.append("\"method\": \"");
sb.append(record.getSourceMethodName());
sb.append("\", ");
// Message
sb.append("\"message\": \"");
sb.append(JSONFilter.escape(formatMessage(record)));
Throwable t = record.getThrown();
if (t != null) {
sb.append("\", ");
// Stack trace
sb.append("\"throwable\": [");
boolean first = true;
do {
if (!first) {
sb.append(',');
} else {
first = false;
}
sb.append('\"').append(JSONFilter.escape(t.toString())).append('\"');
for (StackTraceElement element : t.getStackTrace()) {
sb.append(',').append('\"').append(' ').append(JSONFilter.escape(element.toString())).append('\"');
}
t = t.getCause();
} while (t != null);
sb.append(']');
} else {
sb.append('\"');
}
sb.append('}');
// New line for next record
sb.append(System.lineSeparator());
return sb.toString();
}
/**
* Provides escaping of values so they can be included in a JSON document. Escaping is based on the definition of
* JSON found in <a href="https://www.rfc-editor.org/rfc/rfc8259.html">RFC 8259</a>.
*/
public static class JSONFilter {
/**
* Escape the given string.
*
* @param input the string
*
* @return the escaped string
*/
public static String escape(String input) {
return escape(input, 0, input.length()).toString();
}
/**
* Escape the given char sequence.
*
* @param input the char sequence
* @param off the offset on which escaping will start
* @param length the length which should be escaped
*
* @return the escaped char sequence corresponding to the specified range
*/
public static CharSequence escape(CharSequence input, int off, int length) {
/*
* While any character MAY be escaped, only U+0000 to U+001F (control characters), U+0022 (quotation mark)
* and U+005C (reverse solidus) MUST be escaped.
*/
StringBuilder escaped = null;
int lastUnescapedStart = off;
for (int i = off; i < length; i++) {
char c = input.charAt(i);
if (c < 0x20 || c == 0x22 || c == 0x5c || Character.isHighSurrogate(c) || Character.isLowSurrogate(c)) {
if (escaped == null) {
escaped = new StringBuilder(length + 20);
}
if (lastUnescapedStart < i) {
escaped.append(input.subSequence(lastUnescapedStart, i));
}
lastUnescapedStart = i + 1;
char popular = getPopularChar(c);
if (popular > 0) {
escaped.append('\\').append(popular);
} else {
escaped.append("\\u");
escaped.append(String.format("%04X", Integer.valueOf(c)));
}
}
}
if (escaped == null) {
if (off == 0 && length == input.length()) {
return input;
} else {
return input.subSequence(off, length - off);
}
} else {
if (lastUnescapedStart < length) {
escaped.append(input.subSequence(lastUnescapedStart, length));
}
return escaped.toString();
}
}
private JSONFilter() {
// Utility class. Hide the default constructor.
}
private static char getPopularChar(char c) {
return switch (c) {
case '"', '\\', '/' -> c;
case 0x8 -> 'b';
case 0xc -> 'f';
case 0xa -> 'n';
case 0xd -> 'r';
case 0x9 -> 't';
default -> 0;
};
}
}
}