Spring @Around用于异常处理

Question

The situation is the following: there is a framework that is extended by my application. So I have no main() or any other entry points declared by me (I override methods provided by that framework and it arranges everything else). This framework can be made secure; the security is built on top of apache mina.

When an unsecure connection is made to the app, mina throws an exception, here's the stack trace:

Caused by: javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?
        at sun.security.ssl.EngineInputRecord.bytesInCompletePacket(EngineInputRecord.java:171) ~[na:1.7.0_21]
        at sun.security.ssl.SSLEngineImpl.readNetRecord(SSLEngineImpl.java:845) ~[na:1.7.0_21]
        at sun.security.ssl.SSLEngineImpl.unwrap(SSLEngineImpl.java:758) ~[na:1.7.0_21]
        at javax.net.ssl.SSLEngine.unwrap(SSLEngine.java:624) ~[na:1.7.0_21]
        at org.apache.mina.filter.support.SSLHandler.unwrap0(SSLHandler.java:657) ~[mina-filter-ssl-1.1.7.jar:na]
        at org.apache.mina.filter.support.SSLHandler.unwrapHandshake(SSLHandler.java:613) ~[mina-filter-ssl-1.1.7.jar:na]
        at org.apache.mina.filter.support.SSLHandler.handshake(SSLHandler.java:493) ~[mina-filter-ssl-1.1.7.jar:na]
        at org.apache.mina.filter.support.SSLHandler.messageReceived(SSLHandler.java:306) ~[mina-filter-ssl-1.1.7.jar:na]
        at org.apache.mina.filter.SSLFilter.messageReceived(SSLFilter.java:392) ~[mina-filter-ssl-1.1.7.jar:na]
        ... 12 common frames omitted

I wanted to catch this using an AOP trick, so I can inform the user in a nice way, and can send an alert. I came up with this aspect:

@Aspect
public class SSLExceptionCatcherAdvice {

    private static final Logger LOG = LoggerFactory.getLogger(SSLExceptionCatcherAdvice.class);

    @Around("execution(* *.unwrap(..))")
    public void catchException(ProceedingJoinPoint pjp) {
        try {
            pjp.proceed();
        } catch (Throwable exception) {
            LOG.info("########################################");
        }
    }

}

But, it does not get invoked at all. The aspect is fine, btw, it can catch other method invocations from my codebase.

Any advice on this? Thx in advance.

Answer 1

Spring by default uses a proxy based AOP solution and as a result of that only Spring managed beans will be able to have those aspects applied. It will not work on non-spring managed beans. See this section of the reference guide .

You are trying to intercept the exection on a javax. package which is a special case and will only work in a load-time weaving environment and not with a proxy-based or compile-time based solution. Also weaving them with loadtime weaving might also be tricky as those classes are probably already loaded before loadtime-weaving kicks in.

The aspect is fine, btw, it can catch other method invocations from my codebase.

Actually your aspect is flawed, an @Around advice should always return Object and should always return the result of calling the proceed() method (unless you are rethrowing the Exception . Your aspect breaks properly returning the result and now effectivly every method returns null .

Links:

1. Proxying Mechanisms | reference guide
2. Load-time weaving with AspectJ in the Spring Framework | reference guide
3. Around advice | reference guide