Introducing Spring Framework

Chapter 8 ■ Give Advice to Your Spring Application
As you can see, aspect-oriented programming can help you modularize your concerns by using logging or maybe
caching to separate them from your business logic and thereby avoiding scattering and tangling.
But wait, how will caching use these advices? Well, let’s find out by reviewing Listing 8-14. You are going to use
the around advice type to achieve caching.
Listing 8-14. CachingModule.java
package com.apress.isf.spring.aop;
import java.util.HashMap;
import java.util.Map;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.apress.isf.java.model.Type;
public class CachingModule implements MethodInterceptor {
private static final Logger log = LoggerFactory.getLogger(CachingModule.class);
private static final Map cache = new HashMap();
public Object invoke(MethodInvocation invocation) throws Throwable {
Object result = null;
Type documentType = null;
log.debug("@@@(Caching) review if this call is cachable...");
if("findByType".equals(invocation.getMethod().getName()) &&
invocation.getArguments().length == 1 &&
invocation.getArguments()[0] instanceof Type){
documentType = (Type)invocation.getArguments()[0];
log.debug("@@@(Caching) Is cachable!!");
if(cache.containsKey(documentType.getName())){
log.debug("@@@(Caching) Found in Cache!");
return cache.get(documentType.getName());
}
log.debug("@@@(Caching) Not Found! but is cachable!");
result = invocation.proceed();
cache.put(documentType.getName(), result);
return result;
}
}
return invocation.proceed();
}
Listing 8-14 shows the implementation of the invoke method; here you are going to specialize your logic. You are
going to declare a Map class that will hold the values from different keys; these keys will be the document’s type. You
are going to cache only the findByType method, so if it is called you can see if the document’s type exists in the Map.
If not, you add it into the Map and return it; if it exists in the Map, then just return it.
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