Log4j - Formatting Layouts

Log4j - File Appenders

log4j Resources

log4j - HTMLLayout

Quiz

If you want to generate your logging information in an HTML-formatted file, then you can use org.apache.logging.log4j.HTMLLayout to format your logging information.

The HTMLLayout class extends the abstract org.apache.logging.log4j.Layout class and overrides the format() method from its base class to provide HTML-style formatting.

It provides the following information to be displayed:

The time elapsed from the start of the application before a particular logging event was generated.
The name of the thread that invoked the logging request.
The level associated with this logging request.
The name of the logger and logging message.
The optional location information for the program file and the line number from which this logging was invoked.

HTMLLayout Methods

HTMLLayout is a very simple Layout object that provides the following methods:

Sr.No.	Method & Description
1	setContentType(String) Sets the content type of the text/html HTML content. Default is text/html.
2	setLocationInfo(String) Sets the location information for the logging event. Default is false.
3	setTitle(String) Sets the title for the HTML file. Default is log4j Log Messages.

Example - Usage of HTMLLayout

Following is a simple configuration file for HTMLLayout:

log4j2.properties

// Define a File Appender with HTMLLayout
appender.0.type = File
appender.0.name = MAIN
appender.0.fileName = logs/htmlLayout.html
appender.0.layout.type = HTMLLayout
appender.0.layout.Title=HTML Layout Example
appender.0.layout.LocationInfo=true

rootLogger.level = DEBUG
// Attach the appender to rootLogger
rootLogger.appenderRef.0.ref = MAIN
rootLogger.appenderRef.0.level = INFO

Now consider the following Java Example which would generate logging information:

Log4jDemo.java

package com.tutorialspoint;

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

public class Log4jDemo{

   /* Get actual class name to be printed on */
   private static final Logger LOGGER = LogManager.getLogger();
   
   public static void main(String[] args) {  
      LOGGER.debug("Hello this is an debug message");
      LOGGER.info("Hello this is an info message");
   }
}

Output

Compile and run the above program. It would create an htmlLayout.html file in logs directory which would have the following log information:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta charset="UTF-8"/>
<title>HTML Layout Example</title>
<style type="text/css">
<!--
body, table {font-family:arial,sans-serif; font-size: medium
;}th {background: #336699; color: #FFFFFF; text-align: left;}
-->
</style>
</head>
<body bgcolor="#FFFFFF" topmargin="6" leftmargin="6">
<hr size="1" noshade="noshade">
Log session start time Fri Sep 05 20:06:22 IST 2025<br>
<br>
<table cellspacing="0" cellpadding="4" border="1" bordercolor="#224466" width="100%">
<tr>
<th>Time</th>
<th>Thread</th>
<th>Level</th>
<th>Logger</th>
<th>File:Line</th>
<th>Message</th>
</tr>

<tr>
<td>637</td>
<td title="main thread">main</td>
<td title="Level">INFO</td>
<td title="com.tutorialspoint.Log4jDemo logger">com.tutorialspoint.Log4jDemo</td>
<td>Log4jDemo.java:14</td>
<td title="Message">Hello this is an info message</td>
</tr>
</table>
<br>
</body></html>

You would use a web browser to open htmlLayout.html file.

One of the big advantages of having the log file in HTML format is that it can be published as a web page for remote viewing.

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