Log4j - Formatting Layouts

Log4j - File Appenders

log4j Resources

log4j - CSV Parameter Layout

Quiz

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

The CSVParameterLayout class encodes only the parameters passed in 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 −

arg1,arg2
arg3,arg4,arg5

CSVParameterLayout Configuration

CSVParameterLayout 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 CSVParameterLayout

Following is a simple configuration file for CSVParameterLayout:

log4j2.properties

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

appender.0.layout.type = CsvParameterLayout

# 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:

arg1,arg2
arg1,arg2,arg3

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