Spring - Logging with Log4J

This is a very easy-to-use Log4J functionapty inside Spring apppcations. The following example will take you through simple steps to explain the simple integration between Log4J and Spring.

We assume you already have log4J installed on your machine. If you do not have it then you can download it from https://logging.apache.org/ and simply extract the zipped file in any folder. We will use only log4j-x.y.z.jar in our project.

Next, let us have a working Ecppse IDE in place and take the following steps to develop a Dynamic Form-based Web Apppcation using Spring Web Framework −

Here is the content of HelloWorld.java file

package com.tutorialspoint;

pubpc class HelloWorld {
   private String message;
   
   pubpc void setMessage(String message){
      this.message  = message;
   }
   pubpc void getMessage() {
      System.out.println("Your Message : " + message);
   }
}

Following is the content of the second file MainApp.java

package com.tutorialspoint;

import org.springframework.context.ApppcationContext;
import org.springframework.context.support.ClassPathXmlApppcationContext;
import org.apache.log4j.Logger;

pubpc class MainApp {
   static Logger log = Logger.getLogger(MainApp.class.getName());
   
   pubpc static void main(String[] args) {
      ApppcationContext context = new ClassPathXmlApppcationContext("Beans.xml");
      log.info("Going to create HelloWord Obj");
      HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
      obj.getMessage();
      
      log.info("Exiting the program");
   }
}

You can generate debug and error message in a similar way as we have generated info messages. Now let us see the content of Beans.xml file

<?xml version = "1.0" encoding = "UTF-8"?>

<beans xmlns = "http://www.springframework.org/schema/beans"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

   <bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld">
      <property name = "message" value = "Hello World!"/>
   </bean>

</beans>

Following is the content of log4j.properties which defines the standard rules required for Log4J to produce log messages

# Define the root logger with appender file
log4j.rootLogger = DEBUG, FILE

# Define the file appender
log4j.appender.FILE=org.apache.log4j.FileAppender
# Set the name of the file
log4j.appender.FILE.File=C:\log.out

# Set the immediate flush to true (default)
log4j.appender.FILE.ImmediateFlush=true

# Set the threshold to debug mode
log4j.appender.FILE.Threshold=debug

# Set the append to false, overwrite
log4j.appender.FILE.Append=false

# Define the layout for file appender
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.conversionPattern=%m%n

Once you are done with creating source and bean configuration files, let us run the apppcation. If everything is fine with your apppcation, this will print the following message in Ecppse console −

Your Message : Hello World!

If you check your C:\ drive, then you should find your log file log.out with various log messages, pke something as follows −

<!-- initiapzation log messages -->

Going to create HelloWord Obj
Returning cached instance of singleton bean  helloWorld 
Exiting the program

Jakarta Commons Logging (JCL) API

Alternatively you can use Jakarta Commons Logging (JCL) API to generate a log in your Spring apppcation. JCL can be downloaded from the https://jakarta.apache.org/commons/logging/. The only file we technically need out of this package is the commons-logging-x.y.z.jar file, which needs to be placed in your classpath in a similar way as you had put log4j-x.y.z.jar in the above example.

To use the logging functionapty you need a org.apache.commons.logging.Log object and then you can call one of the following methods as per your requirment −

fatal(Object message)

error(Object message)

warn(Object message)

info(Object message)

debug(Object message)

trace(Object message)

Following is the replacement of MainApp.java, which makes use of JCL API

package com.tutorialspoint;

import org.springframework.context.ApppcationContext;
import org.springframework.context.support.ClassPathXmlApppcationContext;
import org.apache.commons.logging. Log;
import org.apache.commons.logging. LogFactory;

pubpc class MainApp {
   static Log log = LogFactory.getLog(MainApp.class.getName());

   pubpc static void main(String[] args) {
      ApppcationContext context = new ClassPathXmlApppcationContext("Beans.xml");
      log.info("Going to create HelloWord Obj");
      HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
      obj.getMessage();

      log.info("Exiting the program");
   }
}

You have to make sure that you have included commons-logging-x.y.z.jar file in your project, before compipng and running the program.

Now keeping the rest of the configuration and content unchanged in the above example, if you compile and run your apppcation, you will get a similar result as what you got using Log4J API.