Strange behaviour with Ordered.HIGHEST_PRECEDENCE

[gschmutz]

Hi

I have a strange behaviour when ordering advices with the Ordered inteface using Spring AOP. I have created a test project to reproduce it

I have two aspects, AspectA and AspectB, both the same, except of AspectA having HIGHEST_PRECEDENCE as a default value for order and AspectB having LOWEST_PRECEDENCE as the default.

AspectA:

@Aspect
public class AspectA implements Ordered {

	int order = HIGHEST_PRECEDENCE;
	
	public int getOrder() {
		return order;
	}
	
	public void setOrder(int order) {
		this.order = order;
	}

	@Around("execution(* *..*Service.*(..))")
	public Object advice(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
		Object o = null;
		
		System.out.println("AspectA: Before service call....");
		o = proceedingJoinPoint.proceed();
		System.out.println("AspectA: After service call....");
		
		return o;
	}

}

AspectB:

@Aspect
public class AspectB implements Ordered {

	int order = LOWEST_PRECEDENCE;
	
	public int getOrder() {
		return order;
	}
	
	public void setOrder(int order) {
		this.order = order;
	}

	@Around("execution(* *..*Service.*(..))")
	public Object advice(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
		Object o = null;
		
		System.out.println("AspectB: Before service call....");
		o = proceedingJoinPoint.proceed();
		System.out.println("AspectB: After service call....");
		
		return o;
	}

}

When I manually setup the order in the spring configuration (applicationContext-AB.xml)

	<aop:aspectj-autoproxy/>

	<bean id="targetService" class="app.TargetServiceImpl"/>

	<bean class="app.AspectA">
		<property name="order" value="1"/>
	</bean>
		
	<bean class="app.AspectB">
		<property name="order" value="2"/>
	</bean>

Then the chain is setup as expected:

AspectA: Before service call....
AspectB: Before service call....
executing target service ....
AspectB: After service call....
AspectA: After service call....

When I use the default ... by not specifying an order (applicationContext-Default.xml)

	<bean class="app.AspectA">
	</bean>
		
	<bean class="app.AspectB">
	</bean>

then the chain still setup as expected:

AspectA: Before service call....
AspectB: Before service call....
executing target service ....
AspectB: After service call....
AspectA: After service call....

if I only use the default for AspectA, which is HIGHEST_PRECEDENCE (applicationContext-DefaultAnd1.xml)

	<bean class="app.AspectA">
	</bean>
		
	<bean class="app.AspectB">
		<property name="order" value="1"/>
	</bean>

then I get the following interceptor chain

AspectB: Before service call....
AspectA: Before service call....
executing target service ....
AspectA: After service call....
AspectB: After service call....

where B is before A, which I don't understand.

what's even more confusing:if I use the MIN_VALUE constant (same as HIGHEST_PRECEDENCE) hardcoded in the config for the order value of AspectA (applicationContext-NegativeValue.xml)

	<bean class="app.AspectA">
		<property name="order" value="-2147483648"/>
	</bean>
		
	<bean class="app.AspectB">
		<property name="order" value="1"/>
	</bean>

then it again works as expected:

AspectA: Before service call....
AspectB: Before service call....
executing target service ....
AspectB: After service call....
AspectA: After service call....


Do I misunderstand something. Shouldn't HIGHEST_PRECEDENCE mean first in the interceptor chain ? Why is it working with the negative value hardcoded ?

Any suggestions ?

Thanks!