Spring MVC - Integrate LOG4J Example

Step	Description
1	Create a project with the name TestWeb under a package com.howcodex as explained in the Spring MVC - Hello World chapter.
2	Create a Java class HelloController under the com.howcodexpackage.
3	Download the log4j library LOG4J from the maven repository page. Put it in your CLASSPATH.
4	Create a log4j.properties under the SRC folder.
5	The final step is to create the content of the source and configuration files and export the application as explained below.

HelloController.java

package com.howcodex;

import org.apache.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.ui.ModelMap;

@Controller
@RequestMapping("/hello")
public class HelloController{
   private static final Logger LOGGER = Logger.getLogger(HelloController.class);
   @RequestMapping(method = RequestMethod.GET)
   public String printHello(ModelMap model) {
      LOGGER.info("printHello started.");

      //logs debug message
      if(LOGGER.isDebugEnabled()){
         LOGGER.debug("Inside:  printHello");
      }
      //logs exception
      LOGGER.error("Logging a sample exception", new Exception("Testing"));

      model.addAttribute("message", "Hello Spring MVC Framework!");
      LOGGER.info("printHello ended.");
      return "hello";
   }
}

log4j.properties

# Root logger option
log4j.rootLogger = DEBUG, stdout, file

# Redirect log messages to console
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

# Redirect log messages to a log file
log4j.appender.file = org.apache.log4j.RollingFileAppender
#outputs to Tomcat home
log4j.appender.file.File = ${catalina.home}/logs/myapp.log
log4j.appender.file.MaxFileSize = 5MB
log4j.appender.file.MaxBackupIndex = 10
log4j.appender.file.layout = org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

TestWeb-servlet.xml

<beans xmlns = "http://www.springframework.org/schema/beans"
   xmlns:context = "http://www.springframework.org/schema/context"   
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xmlns:mvc = "http://www.springframework.org/schema/mvc"
   xsi:schemaLocation = "
   http://www.springframework.org/schema/beans     
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
   http://www.springframework.org/schema/mvc
   http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
   <context:component-scan base-package = "com.howcodex" />

   <bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver">
      <property name = "prefix" value = "/WEB-INF/jsp/" />
      <property name = "suffix" value = ".jsp" />
   </bean>
</beans>

hello.jsp

<%@ page contentType = "text/html; charset = UTF-8" %>
<html>
   <head>
      <title>Hello World</title>
   </head>
   <body>
      <h2>${message}</h2>
   </body>
</html>

Here, we have configured the LOG4J to log details on the Tomcat console and in the file present in &t; tomcat home → logs as myapp.log.

Once you are done with creating source and configuration files, export your application. Right click on your application, use Export → WAR File option and save your TestWeb.war file in Tomcat's webapps folder.

Now, start the Tomcat server and make sure you are able to access other webpages from the webapps folder using a standard browser. Try a URL −http://localhost:8080/TestWeb/hello and we will see the following screen on Tomcat's log.

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