Log4j2 HTMLLayout Configuration Example

This Log4j2 example will help you in configuring log4j2.xml file with HTMLLayout. The HTMLLayout generates an HTML page and adds each log statement to a row in a table.

1. HTMLLayout Configuration Options

You can use following attributes while configuring HTMLLayout:

1. locationInfo – If “true”, location information will be included. The default is false.
2. title – The title to include in the file header. If none is specified the default title will be used.
3. contentType – The content type. Defaults to “text/html”.
4. charset – The character set to use. If not specified, the default will be used.
5. fontSize – The font size of the text.
6. font – The font to use for the text.

Let’s see different configurations options for generating HTML format-based log files.

1.1. Log4j2.xml Configuration

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn">
    <Properties>
        <Property name="basePath">C:\\logs</Property>
    </Properties>
    <Appenders>
        <RollingFile name="fileLogger" fileName="${basePath}/app-info.html" 
        			 filePattern="${basePath}/app-info-%d{yyyy-MM-dd}.html">
            <HTMLLayout charset="UTF-8" title="Howtodoinjava Info Logs" locationInfo="true" />
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true" />
                <SizeBasedTriggeringPolicy size="10 MB" />
            </Policies>
        </RollingFile>
        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout   pattern="[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Logger name="com.howtodoinjava" level="debug" additivity="false">
            <appender-ref ref="fileLogger" level="debug" />
        </Logger>
        <Root level="debug" additivity="false">
            <appender-ref ref="console" />
        </Root>
    </Loggers>
</Configuration>

1.2. Log4j2.properties Configuration

status = error
name = PropertiesConfig
 
#Make sure to change log file path as per your need
property.filename = C:\\logs\\app-info.html
 
filters = threshold
 
filter.threshold.type = ThresholdFilter
filter.threshold.level = debug
 
appenders = rolling
 
appender.rolling.type = RollingFile
appender.rolling.name = RollingFile
appender.rolling.fileName = ${filename}
appender.rolling.filePattern = debug-backup-%d{MM-dd-yy-HH-mm-ss}-%i.html.gz
appender.rolling.layout.type = HTMLLayout
appender.rolling.layout.charset = UTF-8
appender.rolling.layout.title = Howtodoinjava Info Logs
appender.rolling.layout.locationInfo = true
appender.rolling.policies.type = Policies
appender.rolling.policies.time.type = TimeBasedTriggeringPolicy
appender.rolling.policies.time.interval = 1
appender.rolling.policies.time.modulate = true
appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
appender.rolling.policies.size.size=10MB
appender.rolling.strategy.type = DefaultRolloverStrategy
appender.rolling.strategy.max = 20
 
loggers = rolling
 
#Make sure to change the package structure as per your application
logger.rolling.name = com.howtodoinjava
logger.rolling.level = debug
logger.rolling.additivity = false
logger.rolling.appenderRef.rolling.ref = RollingFile

1.3. Log4j2.json Configuration

{
   "configuration": {
      "name": "Default",
      "appenders": {
         "RollingFile": {
            "name":"File",
            "fileName":"C:/logs/howtodoinjava.html",
            "filePattern":"C:/logs/howtodoinjava-backup-%d{MM-dd-yy-HH-mm-ss}-%i.html.gz",
            "HTMLLayout": {
               "charset":"UTF-8",
               "title":"Howtodoinjava Info Logs",
               "locationInfo":"true"
            },
            "Policies": {
               "SizeBasedTriggeringPolicy": {
                  "size":"10 MB"
               }
            },
            "DefaultRolloverStrategy": {
               "max":"10"
            }
         }
      },
      "loggers": {
         "root": {
            "level":"debug",
            "appender-ref": {
              "ref":"File"
            }
         }
      }
   }
}

2. Log Statements

Now let’s use dome log statements to generate log files.

package com.howtodoinjava.log4j2.examples;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class Log4j2HelloWorldExample 
{
	private static final Logger LOGGER = LogManager.getLogger(Log4j2HelloWorldExample.class.getName());
	
	public static void main(String[] args) 
	{
		LOGGER.debug("Debug Message Logged !!");
		LOGGER.info("Info Message Logged !!");
		LOGGER.debug("Another Debug Message !!");
	}
}

3. Log4j2 HTMLLayout Output Example

Running the above log files will generate the following HTML file.

Drop me your questions in the comments section.

Reference:

http://logging.apache.org/log4j/2.x/manual/layouts.html#HTMLLayout
https://logging.apache.org/log4j/2.x/log4j-core/apidocs/org/apache/logging/log4j/core/layout/HtmlLayout.html