java code for Aspect Hello World Example

/*
Pro Spring
By Rob Harrop
Jan Machacek
ISBN: 1-59059-461-4
Publisher: Apress
*/



///////////////////////////////////////////////////////////////////////////////////////

public interface IMessageWriter {

public void writeMessage();
}


///////////////////////////////////////////////////////////////////////////////////////


public class MessageWriter implements IMessageWriter{

public void writeMessage() {
System.out.print("World");
}

}
///////////////////////////////////////////////////////////////////////////////////////

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;


public class MessageDecorator implements MethodInterceptor {

public Object invoke(MethodInvocation invocation) throws Throwable {
System.out.print("Hello ");
Object retVal = invocation.proceed();
System.out.println("!");
return retVal;
}

}

///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.aop.framework.ProxyFactory;

public class HelloWorldAOPExample {

public static void main(String[] args) {
MessageWriter target = new MessageWriter();

// create the proxy
ProxyFactory pf = new ProxyFactory();

pf.addAdvice(new MessageDecorator());
pf.setTarget(target);


MessageWriter proxy = (MessageWriter) pf.getProxy();

// write the messages
target.writeMessage();
System.out.println("");
proxy.writeMessage();
}
}