Question

Little confused, the basic spring mvc app has this:

app-config.xml

<context:component-scan base-package="org.springframework.samples.mvc.basic" />

and the mvc-config.xml has:

<!-- Configures the @Controller programming model -->
    <mvc:annotation-driven />

1. Do you really need both?

2. for component-scan, does this mean if I don’t put the correct package path my @Controller and @Service markers will have no effect?
   If I need more than one package, do I just duplicate the entry?

I tried using just the mvc:annotation-driven but that didn’t work, I had to put com.example.web.controllers in the component-scan xml node to make it work.

Answer 1

context:component-scan is clear

Scans the classpath for annotated components that will be auto-registered as Spring beans. By default, the Spring-provided @Component, @Repository, @Service, and @Controller stereotypes will be detected.

So @Controller is just a Spring bean. Nothing else.

And

mvc:annotation-driven

registers the HandlerMapping and HandlerAdapter required to dispatch requests to your @Controllers

Which is similar to

<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/>
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>

If I need more than one package, do I just duplicate the entry?

You can if you want. context:component-scan is just a bean post-processor.

<context:component-scan base-package="br.com.app.view.controller"/>
<context:component-scan base-package="br.com.app.service"/>

Or

Use a comma-separated list of packages to scan for annotated components.

<context:component-scan base-package="br.com.app.view.controller,br.com.app.service"/>