package org.objectweb.celtix.common.annotation;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.objectweb.celtix.common.i18n.Message;
import org.objectweb.celtix.common.logging.LogUtils;
/** Process instance of an annotated class. This is a visitable
* object that allows an caller to visit that annotated elements in
* this class definition. If a class level annotation is overridden
* by a member level annotation, only the visit method for the member
* level annotation
*/
public class AnnotationProcessor {
private static final Logger LOG = LogUtils.getL7dLogger(AnnotationProcessor.class);
private static Method visitClassMethod;
private static Method visitFieldMethod;
private static Method visitMethodMethod;
static {
try {
visitClassMethod = AnnotationVisitor.class.getMethod("visitClass", Class.class, Annotation.class);
visitFieldMethod = AnnotationVisitor.class.getMethod("visitField", Field.class, Annotation.class);
visitMethodMethod = AnnotationVisitor.class.getMethod("visitMethod",
Method.class, Annotation.class);
} catch (NoSuchMethodException e) {
// ignore
}
}
private final Object target;
private List<Class<? extends Annotation>> annotationTypes;
public AnnotationProcessor(Object o) {
if (o == null) {
throw new IllegalArgumentException(new Message("INVALID_CTOR_ARGS", LOG).toString());
}
target = o;
}
/**
* Visits each of the annotated elements of the object.
*
* @param visitor a visitor
*
*/
public void accept(AnnotationVisitor visitor) {
if (visitor == null) {
throw new IllegalArgumentException();
}
annotationTypes = visitor.getTargetAnnotations();
visitor.setTarget(target);
processClass(visitor);
processFields(visitor);
processMethods(visitor);
}
private void processMethods(AnnotationVisitor visitor) {
visitAnnotatedElement(target.getClass().getDeclaredMethods(), visitor, visitMethodMethod);
}
private void processFields(AnnotationVisitor visitor) {
visitAnnotatedElement(target.getClass().getDeclaredFields(), visitor, visitFieldMethod);
}
private void processClass(AnnotationVisitor visitor) {
Class<?>[] classes = {target.getClass()};
visitAnnotatedElement(classes, visitor, visitClassMethod);
}
private <U extends AnnotatedElement> void visitAnnotatedElement(U[] elements,
AnnotationVisitor visitor,
Method visitorMethod) {
for (U element : elements) {
for (Class<? extends Annotation> clz : annotationTypes) {
Annotation ann = element.getAnnotation(clz);
if (ann != null) {
try {
visitorMethod.invoke(visitor, element, ann);
} catch (IllegalAccessException e) {
// ignore, we're invoking methods of a public interface
} catch (InvocationTargetException e) {
Throwable cause = e.getCause() == null ? e : e.getCause();
LogUtils.log(LOG, Level.SEVERE, "VISITOR_RAISED_EXCEPTION", cause, visitor);
}
}
}
}
}
}