/*
* Copyright 2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.util;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;
/**
* A {@link FieldCallback} that will inspect each field for a given annotation. Thie fields type can then be accessed
* afterwards.
*
* @author Oliver Gierke
*/
public class AnnotationDetectionFieldCallback implements FieldCallback {
private final Class<? extends Annotation> annotationType;
private Field field;
/**
* Creates a new {@link AnnotationDetectionFieldCallback} scanning for an annotation of the given type.
*
* @param annotationType must not be {@literal null}.
*/
public AnnotationDetectionFieldCallback(Class<? extends Annotation> annotationType) {
Assert.notNull(annotationType);
this.annotationType = annotationType;
}
/*
* (non-Javadoc)
* @see org.springframework.util.ReflectionUtils.FieldCallback#doWith(java.lang.reflect.Field)
*/
public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
if (this.field != null) {
return;
}
Annotation annotation = field.getAnnotation(annotationType);
if (annotation != null) {
this.field = field;
}
}
/**
* Returns the type of the field.
*
* @return
*/
public Class<?> getType() {
return field == null ? null : field.getType();
}
/**
* Retrieves the value of the field by reflection.
*
* @param source must not be {@literal null}.
* @return
*/
@SuppressWarnings("unchecked")
public <T> T getValue(Object source) {
Assert.notNull(source);
return field == null ? null : (T) ReflectionUtils.getField(field, source);
}
}