자바 리플렉션을 사용함으로서 런타임에 자바클래스에 정의되있는 어노테이션 정보에 접근할수있다.
클래스 어노테이션
Class aClass = TheClass.class;
Annotation[] annotations = aClass.getAnnotations();
for(Annotation annotation : annotations){
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
}
요렇게 접근가능하다:
Class aClass = TheClass.class;
Annotation annotation = aClass.getAnnotation(MyAnnotation.class);
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
Method 어노테이션
public class TheClass {
@MyAnnotation(name="someName", value = "Hello World")
public void doSomething(){}
}
요렇게 접근가능하다:
Method method = ... //obtain method object
Annotation[] annotations = method.getDeclaredAnnotations();
for(Annotation annotation : annotations){
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
}
요렇게도 접근가능하다:
Method method = ... // obtain method object
Annotation annotation = method.getAnnotation(MyAnnotation.class);
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
Parameter 어노테이션
public class TheClass {
public static void doSomethingElse(
@MyAnnotation(name="aName", value="aValue") String parameter){
}
}
요렇게 접근가능하다:
Method method = ... //obtain method object
Annotation[][] parameterAnnotations = method.getParameterAnnotations();
Class[] parameterTypes = method.getParameterTypes();
int i=0;
for(Annotation[] annotations : parameterAnnotations){
Class parameterType = parameterTypes[i++];
for(Annotation annotation : annotations){
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("param: " + parameterType.getName());
System.out.println("name : " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
}
}
Method.getParameterAnnotations() 메소드는 2차원 배열을 리턴한다는걸 주목하라.
그것은 메소드파라미터 각각의 어노테이션 배열을 포함한다.
Field 어노테이션
public class TheClass {
@MyAnnotation(name="someName", value = "Hello World")
public String myField = null;
}
요렇게 접근가능하다:
Field field = ... //obtain field object
Annotation[] annotations = field.getDeclaredAnnotations();
for(Annotation annotation : annotations){
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}
}
요렇게도 접근가능하다:
Field field = ... // obtain method object
Annotation annotation = field.getAnnotation(MyAnnotation.class);
if(annotation instanceof MyAnnotation){
MyAnnotation myAnnotation = (MyAnnotation) annotation;
System.out.println("name: " + myAnnotation.name());
System.out.println("value: " + myAnnotation.value());
}