com.jdon.annotation

注释类型 Singleton

@Target(value=TYPE)
 @Retention(value=RUNTIME)
 @Documented
public @interface Singleton

the @Component is equals to: <component name="abc" class="com.sample.Abc" /> the @Component's name will be the class's getClass.getName(); Component not open for the client, so default no need name, but if you call the component from the client, you can use the @Component's name(class's getClass.getName()).