AOP for Logging without changing code

[mittalramsharan]

Hi Springians

we have a big project in Spring and in next phase we are going to adding logging functionality, Old existing code is working fine after a rigirous testing so without chaning any code can it be log it in between of some existing. Please suggest some mature and quality suggestion. with sample code if possible.

[ChetanAggarwal]

Hi,

You can use Spring's AOP to write a generic around advice and log method signatures, parameters and return values.

I tried following as examples:

LoggingAspect is simple POJO aspect.

public class LoggingAspect {

	Logger logger = Logger.getLogger(LoggingAspect.class);


	public Object log(ProceedingJoinPoint pjp) throws Throwable {
		
		//Log method name, input
		Signature sig = pjp.getSignature();
		String sigName = sig.getDeclaringTypeName() + "." + sig.getName();
		String arguments = "(";
		Object[] args = pjp.getArgs();
		if (args != null) {
			for (int i = 0; i< args.length ; i++) {
				arguments += args[i] + ",";
			}
		}
		arguments += ")";
		System.out.println(sigName + arguments);
		
		Object ret = pjp.proceed();
		System.out.println("Returned:[" + (ret) + "]");
		return ret;
		
	}
}

	<aop:config>
		<aop:pointcut id="loggerMethods"
			expression="execution(* com.examples..*.*(..))"/>

		<aop:aspect id="logger" ref="loggerAspect">

			<aop:around pointcut-ref="loggerMethods" method="log"/>
		</aop:aspect>

	</aop:config>


	<bean id="loggerAspect" class="com.examples.aop.logging.LoggingAspect" />

Above aspect is logging method signature with parameters and return values for all methods in "com.examples" package classes and sub packages.

Regards
Chetan

[nicolas.loriente]

From Spring Documentation [ http://static.springsource.org/sprin...rence/aop.html ]:

"Spring AOP currently supports only method execution join points (advising the execution of methods on Spring beans)."

So, if what you are trying to intercept with Spring AOP is a Spring bean then yes, it will work. But if it is not, then you'll need a full blown AOP solution such as AspectJ.

The reason for this is that Spring AOP is a proxy-based AOP framework.

For more information on Spring AOP check the documentation (link above).

I hope it helps.