jodd.util.AnnotationDataReader Maven / Gradle / Ivy
// Copyright (c) 2003-2011, Jodd Team (jodd.org). All Rights Reserved.
package jodd.util;
import jodd.typeconverter.Convert;
import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
/**
* Annotation reader that reads an annotation and returns annotation data object filled
* with annotation element values. May be used when having two or more annotations with
* same elements - since java doesn't support annotation inheritance.
*/
public abstract class AnnotationDataReader> {
protected final Class annotationClass;
// ---------------------------------------------------------------- ctor
/**
* Creates new annotation data reader using annotation definition
* from class generics.
*/
@SuppressWarnings( {"unchecked"})
protected AnnotationDataReader() {
annotationClass = ReflectUtil.getGenericSupertype(this.getClass());
if (annotationClass == null) {
throw new IllegalArgumentException("Unable to resolve annotation from generic supertype.");
}
}
/**
* Creates new annotation data reader using provided annotation class.
*/
protected AnnotationDataReader(Class annotationClass) {
this.annotationClass = annotationClass;
}
// ---------------------------------------------------------------- methods
/**
* Returns annotation class.
*/
public Class getAnnotationClass() {
return annotationClass;
}
/**
* Returns true if annotation is present on
* given accessible object.
*/
public boolean hasAnnotation(AccessibleObject accessibleObject) {
return accessibleObject.isAnnotationPresent(annotationClass);
}
/**
* Reads {@link AnnotationData annotation data} on provided accessible object.
* If annotation is not presented, null is returned.
*/
public D readAnnotationData(AccessibleObject accessibleObject) {
A annotation = accessibleObject.getAnnotation(annotationClass);
if (annotation == null) {
return null;
}
return createAnnotationData(annotation);
}
/**
* Creates annotation data from given annotation.
*/
protected abstract D createAnnotationData(A annotation);
// ---------------------------------------------------------------- read
/**
* Reads non-empty, trimmed, annotation element value. If annotation value is
* an empty string, returns null.
*/
protected String readStringElement(A annotation, String name) {
String value = Convert.toString(ReflectUtil.readAnnotationValue(annotation, name));
if (value != null) {
value = value.trim();
if (value.length() == 0) {
value = null;
}
}
return value;
}
/**
* Reads annotation element as an object.
*/
protected Object readElement(A annotation, String name) {
return ReflectUtil.readAnnotationValue(annotation, name);
}
// ---------------------------------------------------------------- annotation data
/**
* Base class for annotation data, for holding annotation elements values.
*/
public abstract static class AnnotationData {
protected final N annotation;
protected AnnotationData(N annotation) {
this.annotation = annotation;
}
/**
* Returns annotation.
*/
public N getAnnotation() {
return annotation;
}
}
}