I am trying to implement one of the suggestion given by our stackoverflow member here Logging entry, exit and exceptions for methods in java using aspects . Since this is different question in itself, posting here again.
I have tried to search but looks like different versions have different ways of doing it and unable to figure out an example online. I have tried the following simple example since I am new to aspect oriented programming and couldn't figure out how to implement. This example is throwing NPE. Please help me understand where I am doing it wrong.
==== Exception
Exception in thread "main" java.lang.NullPointerException at aoplogging.SimpleCall.call(SimpleCall.java:13) at aoplogging.App.main(App.java:18) Exactly at SimpleService.simpleCall();
ApplicationContext:
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:task="http://www.springframework.org/schema/task" xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd"> <aop:aspectj-autoproxy /> <bean id="simpleCall" class="aoplogging.SimpleCall" /> ================== App.java
package aoplogging; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class App { public static void main(String[] args) { ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml"); SimpleCall call =(SimpleCall) context.getBean("simpleCall"); call.call(); context.close(); } ============ SimpleCall.java package aoplogging;
import org.springframework.beans.factory.annotation.Autowired; public class SimpleCall { @Autowired private SimpleService SimpleService; public void call(){ SimpleService.simpleCall(); try { SimpleService.processingOperator(); } catch (SMSProcessingException | SMSSystemException e) { e.printStackTrace(); } } }
=====Logging.java
package aoplogging; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.AfterThrowing; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; @Aspect public class Logging { @Pointcut("execution(* aoplogging.*.*(..))") private void selectAll(){} /** * This is the method which I would like to execute * before a selected method execution. */ @Before("selectAll()") public void beforeAdvice(){ System.out.println("Going to setup student profile."); } /** * This is the method which I would like to execute * after a selected method execution. */ @After("selectAll()") public void afterAdvice(){ System.out.println("Student profile has been setup."); } /** * This is the method which I would like to execute * when any method returns. */ @AfterReturning(pointcut = "selectAll()", returning="retVal") public void afterReturningAdvice(Object retVal){ System.out.println("Returning:" + retVal.toString() ); } /** * This is the method which I would like to execute * if there is an exception raised by any method. */ @AfterThrowing(pointcut = "selectAll()", throwing = "ex") public void AfterThrowingAdvice(IllegalArgumentException ex){ System.out.println("There has been an exception: " + ex.toString()); } }