Simplified version of Log4j in Java

Introduction

• In Eclipse or any IDE (Integrated development environment), the console has a limited memory to store all the logs or print the messages like errors, exceptions etc.. Therefore log4j was invented.

• Log4j is a logging tool.

• We can get and store the logs/messages in following formats:

1.File (name.log)

2.Database

3.Email (send mail)

4.Console

• Logs are usually used by support team or Dev team to read the errors and fix the issues.

Steps on how to check the console memory in Eclipse

Window->Preferences->Run/Debug->Console-see the memory i.e. 80000

Log4j framework components

• Logger

• Layout

• Appender

Picture courtesy: innovationm.co

Logger

• Logger must be created inside the class for which Log4j is required.

• Eg. There are 3 class, choose which class needs the Log4j where there are chances of highest errors.

Appender

• It is used to specify where to store the log message.

• Types of Appenders:

1. Console Appender: To print the log on console.

2. File Appender: Store the log in .log file.

3. JDBC Appender: To store the message in database table.

4. FTP/ Telnet Appender : Send the data from one server to another.

5. SMTP : Send the log using mail.

Layout

• We can indicate which format should be printed on Appender.

1. Simple Layout

2. HTML layout : Print the messages in HTML format.

3. XML Layout: Print the messages as XML output.