Spring Annotation

1. Special Annotation to mark beans provided by Spring.

@Component: To mark a class of ordinary Spring bean.
@Controller: To mark a class of controller component.
@Service: To mark a class of logic service. (usually under service package.)
@Repository: To mark a class of DAO component. (Usually under xxxDAO package.)

@Scope: To assign the scope for bean. @Scope("prototype") @Scope("singleton")

---

So you do not need to configurate them in Spring config file of applicationContext.xml.
But you should designate the path to search the beans in applicationContext.xml.

<!-- auto to san all the beans of the package and son-packages. -->
<context:conponent-scan base-package="com.bupt.huang"/>

Or you can also add elements like<include-filter>, <exclude-filter>.

<context:component-scan base-package="com.bupt.huang">
    <!-- All the classes end with Chinese will be included. -->
    <context:include-filter type="regex" expression=".*Chinese"/>
    <!-- All the classes end with Axe will be excluded. -->
    <context:exclude-filter type="regex" expression=".*Axe"/>
</context:component-scan>

    <!-- 
type: to point out the filter type. There 4 kind of types:
    annotation, regex, assignable(to specify a class name), aspectj.
     -->

---

4 kinds of Annotation.

//Or you can mark the name of the bean instance. @Component("chinese")
@Componnet
public class Chinese implements Person{
    private int year;   // class attributes.
    private Axe axe; // IoC, or dependency injection. Set way. Anther way is by constructor.
    public void setAxe(Axe axe){
        this.axe = axe;
    }
    /** skip other methods. */
}

@Repository
public class UseDAO{
    /** skip. */
}

@Service
public class UserService{
    /** skip. */
}

@Controller
public class LoginController {
    /** skip. */
}

---

@Resource(name="stoneAxe")
@PostConstruct
@PreDestroy

@Component
public class Chinese implements Person {
    // If you use @Resource annotation, then you don't need to realize setXXX() method.
    @Resource(name="steelAxe")  
    private Axe axe;
    public void useAxe(){
        System.out.println(axe.chop());
    }
    @PostConstruct
    public void init(){
        System.out.println("method before init bean..");
   }
    @PreDestroy
    public void close(){
        System.out.println("method before destroy bean.");
    }
}

---

@DependsOn({"aBean", "bBean"}) //to modify a class or method.
@Lazy(true) //true to not pre-init a bean class when Spring container inits.
@AutoWired // auto search and load to setXXX().
@Qualifer("student") // student is the name of bean instance.