Autowired, Resource, Inject

In chapter three, Introducing IoC and DI in Spring, of Pro Spring 5, I have read the example about Using Setter Injection in the annotation flavor, where for the "renderer" service the Autowired annotation was used in its setter to inject the "provider" bean in its parameter.
A note hints that other annotations, Resource and Inject, could be used, but no example is provided. I thought it was better to practice a bit on them too.

Autowired

The provided example is actually what we usually see in Spring code:

@Override
@Autowired
public void setMessageProvider(MessageProvider provider) {
    this.messageProvider = provider;
}

We should only be aware that Autowired is pure Spring, as its full name documents.

Inject

We could get the same result using the JSR standard annotation Inject:

@Override
@Inject
public void setMessageProvider(MessageProvider provider) {
    this.messageProvider = provider;
}

I had to change the provided build.gradle file for chapter three, setter-injection project, since it didn't have the compile dependency for injection, named misc.inject and defined in the main build.gradle file as

inject         : "javax.inject:javax.inject:1"

Autowired and Qualifier

Say that we have more than one Component implementing the MessageProvider interface. The default one is name "provider", and so it is chosen by Spring in the above examples. But what if I want to inject a different one, for instance "pro2":

@Component("pro2")
class MessageProvider2 implements MessageProvider {

    @Override
    public String getMessage() {
        return "Hello from Message Provider 2!";
    }
}

The Spring commonly used approach is using the Qualifier annotation.

@Override
@Autowired
@Qualifier("pro2")
public void setMessageProvider(MessageProvider provider) {
    this.messageProvider = provider;
}

Both Autowired and Qualifier are Spring specific annotations.

Resource

A JSR standard alternative to the couple Autowired + Qualifier is given by the Resource annotation.

@Override
@Resource(name = "pro3")
public void setMessageProvider(MessageProvider provider) {
    this.messageProvider = provider;
}

Here above, the Component named "pro3" is going to be injected in provider.

Inject and Named

Another JSR standard alternative to Autowired + Qualifier is provided by the couple Inject + Named.

@Override
@Inject
@Named("pro4")
public void setMessageProvider(MessageProvider provider) {
    this.messageProvider = provider;
}

I have pushed to GitHub my changes. You could see there the build.gradle file, my new Components, and the alternative setters.