Introducing Spring Framework

Chapter 1 ■ Your First Spring Application
Listing 1-2 shows a simple Interface with only one method.
Listing 1-2. MessageService.java
package com.apress.isf.spring;
public interface MessageService {
public String getMessage();
}
Next, let’s create the HelloWorldMessage that will return just the simple “Hello World” (see Listing 1-3).
Listing 1-3. HelloWorldMessage.java
package com.apress.isf.spring;
public class HelloWorldMessage implements MessageService {
}
public String getMessage(){
return "Hello World";
}
Listing 1-3 shows the implementation of the interface in Listing 1-2. You can make any implementation you want
if you keep following the contract that your interface provides. For example, right now you just return a string, but you
can actually call a service or go into a database and pick a random message.
■ ■Note All of these examples can be edited using any text editor or any favorite IDE (integrated development
environment).
Now you are ready to test your implementation, but you need to add a starting point.
Running the Hello World Application
Listing 1-4 shows the main class where you are going to test your MessageService class implementation (Listing 1-3,
the HelloWorldMessage class). Now you need to take a look at Listing 1-4, because I am introducing some annotations
(annotations were introduced as a new feature in Java 5). These annotations are markers for the Spring Framework to
help understand your classes and they collaborate together. But wait! Spring Framework? Right now you are going to
run this example as it is; later in this and the following chapter, you will learn what the Spring Framework is and how it
can help you to deliver enterprise-ready applications.
Listing 1-4. Application.java
package com.apress.isf.spring;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation. AnnotationConfigApplicationContext;
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