Introducing Spring Framework

Chapter 8 ■ Give Advice to Your Spring Application
}
}
try{
engineProxy.findByLocation("/some/path/");
}catch(Exception ex){
log.error(ex.getMessage());
}
If you run this test with
gradle :ch08:test
you will have the following output:
2014-02-23 20:04:06,217 DEBUG [main] Using Spring AOP:
2014-02-23 20:04:06,404 ERROR [main] findByLocation not yet implemented.
Where are the logs? Well, you removed them from your implementation (see SearchEngineService.java, which
is shown in Listing 8-3). You also added a new method in your interface (see Listing 8-2). And in your implementation
you just throw an UnsupportedOperationException exception, that’s why you are seeing the error log.
Next, let’s learn more about each advice type: before, after, around, and after throw.
Before Advice
You are going to create your first advice type. Spring AOP provides a MethodBeforeAdvice interface, and it provides a
before method for its implementation. This method will be called before the object’s method execution (see Listing 8-6).
In other words, you are intercepting a method call before its execution.
Listing 8-6. BeforeLoggingModule.java
package com.apress.isf.spring.aop;
import java.lang.reflect.Method;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.aop.MethodBeforeAdvice;
public class BeforeLoggingModule implements MethodBeforeAdvice {
private static final Logger log = LoggerFactory.getLogger(BeforeLoggingModule.class);
}
96
public void before(Method method, Object[] args, Object target)
throws Throwable {
if(log.isDebugEnabled()){
log.debug("@@@@(BEFORE) Method called: " + method.getName());
if(args.length ==0 )
log.debug("@@@@(BEFORE) No arguments passed.");
for(Object arg:args)
log.debug("@@@@(BEFORE) Argument passed:" + arg);
}
}