Log4j - Formatting Layouts

Log4j - File Appenders

log4j Resources

log4j - CSV Log Event Layout

Quiz

If you want to encode your complete logging information in an CSV-formatted file, then you can use org.apache.logging.log4j.CSVLogEventLayout to format your logging information.

The CSVLogEventLayout class encodes all details of the message of log event.

For example, consider the below log statements −

LOGGER.info("Record 1 {} {}", "arg1", "arg2");
LOGGER.error("Record 2 {} {} {}", "arg3", "arg4", "arg5", throwable);

The resulted logs will contain following entries in CSV format −

0,1757242265192,DEBUG,1,main,5,Record 1 arg1 arg2,org.apache.logging.log4j.spi.AbstractLogger,com.tutorialspoint.Log4jDemo,,,com.tutorialspoint.Log4jDemo.main(Log4jDemo.java:12),{},[]
0,1757242265199,INFO,1,main,5,Record 2 arg1 arg2 arg3,org.apache.logging.log4j.spi.AbstractLogger,com.tutorialspoint.Log4jDemo,,,com.tutorialspoint.Log4jDemo.main(Log4jDemo.java:13),{},[]

CSVLogEventLayout Fields

CSVLogEventLayout generate records with following fields of a log event:

Time (in nanoseconds)
Time (in milliseconds)
Level
Thread ID
Thread name
Thread priority
Message (formatted, hence including parameters)
Logger FQCN
Logger name
Marker
Throwable
Source
Thread context map
Thread context stack

CSVLogEventLayout Configuration

CSVLogEventLayout can be configured with following parameters:

Parameter	Type	Description
format	String	A predefined format name (Default, Excel, MySQL, RFC4180, TDF, etc.) accepted by CSVFormat
delimiter	Character	The field delimiter character
escape	Character	The escape character
quote	Character	The quote character
quoteMode	String	A quote mode name (ALL, ALL_NONE_NULL, MINIMAL, NON_NUMERIC, NONE, etc.) accepted by QuoteMode
nullString	String	The string to denote null values
recordSeparator	String	The record separator string
charset	Charset	The character encoding
header	String	The header to include when the stream is opened
footer	String	The footer to include when the stream is closed

We need following jars in the classpath −

commons-csv-1.14.1.jar

commons-codec-1.19.0.jar

Example - Usage of CSVLogEventLayout

Following is a simple configuration file for CSVLogEventLayout:

log4j2.properties

# Define the appender
appender.0.type = Console
appender.0.name = CONSOLE

appender.0.layout.type = CSVLogEventLayout

# Define the root logger with appender Console
rootLogger.level = DEBUG
rootLogger.appenderRef.0.ref = CONSOLE

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("Record 1 {} {}", "arg1", "arg2");
      LOGGER.info("Record 2 {} {} {}", "arg1", "arg2", "arg3");
   }
}

Output

Compile and run the above program. Console will print the following log information:

0,1757242265192,DEBUG,1,main,5,Record 1 arg1 arg2,org.apache.logging.log4j.spi.AbstractLogger,com.tutorialspoint.Log4jDemo,,,com.tutorialspoint.Log4jDemo.main(Log4jDemo.java:12),{},[]
0,1757242265199,INFO,1,main,5,Record 2 arg1 arg2 arg3,org.apache.logging.log4j.spi.AbstractLogger,com.tutorialspoint.Log4jDemo,,,com.tutorialspoint.Log4jDemo.main(Log4jDemo.java:13),{},[]

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