AspectJ Load Time Weaving in Spring web application

What is LTW?

Load-time weaving (LTW) is simply binary weaving defered until the point that a class loader loads a class file and defines the class to the JVM. To support this, one or more "weaving class loaders", either provided explicitly by the run-time environment or enabled through a "weaving agent" are required.

Following the below mentioned steps to enabled AspectJ LTW in any web based application.

Step 1: Create Aspect class

Create ProfilingAspect like below

package com.test.peek.agent;

import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Pointcut;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

@Aspect

public class ProfilingAspect {

private static Logger logger = LoggerFactory.getLogger(ProfilingAspect.class);

@Around("methodsToBeProfiled()")

    public Object profile(ProceedingJoinPoint pjp) throws Throwable {        

        try {        

           

            logger.info("****************************************************Going to call the method.**************************************");

            return pjp.proceed();

        } finally {

            logger.info("****************************************************Method Execution completed.**************************************");

        }

       

    }

    @Pointcut("execution(public * com.test.peek..*.*(..))")

    public void methodsToBeProfiled(){}

   

}

Step 2:  Creat aop.xml in META-INF folder

Create aop.xml in META-INF folder with the following content.

<!DOCTYPE aspectj PUBLIC

        "-//AspectJ//DTD//EN" "http://www.eclipse.org/aspectj/dtd/aspectj.dtd">

<aspectj>

    <weaver>

       <exclude within="*..*CGLIB*" />

        <!-- only weave classes in our application-specific packages -->

        <include within="com.test.peek.web.service.SearchService"/>

         <!-- Package name of Aspect class -->

        <include within="com.test.peek.agent.*"/>
        <include within="com.test.peek.agent.ProfilingAspect"/>

    </weaver>

    <aspects>

        <!-- weave in just this aspect -->        

        <aspect name="com.test.peek.agent.ProfilingAspect"/>

    </aspects>

  </aspectj>

Step 3: Passing spring-instrument jar path as a VM -javaagent argument

The below mentioned argument should be passed as an VM argument while starting tomcat server.

-javaagent:/Users/test.m2/repository/org/aspectj/aspectjweaver/1.7.2/aspectjweaver-1.7.2.jar

Step 4: Maven Dependency

  <dependency>

  <groupId>org.aspectj</groupId>

  <artifactId>aspectjweaver</artifactId>

  <version>1.7.0</version>

  </dependency>

Just follow the above mentioned step to enable LTW in any web based application.

For more details refer : http://www.eclipse.org/aspectj/doc/released/devguide/ltw-configuration.html.