Java Reflection Annotation Find findAnnotation(Class clazz, Class annotationType)

License

Parameter

Return

Declaration

public static <A extends Annotation> A findAnnotation(Class<?> clazz, Class<A> annotationType) 

Method Source Code

//package com.java2s;
/**//from   w ww.j  a v a2 s.com
 * Copyright (c) 2013 Andre Ricardo Schaffer
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

import java.lang.annotation.Annotation;

public class Main {
    /**
     * Finds an annotation in a class type hierarchy. <br/>
     * Code removed from spring-core.
     * 
     * @param <A> The annotation type.
     * @param clazz The class.
     * @param annotationType The annotation.
     * @return The annotation found or null.
     * @since 0.3.0
     */
    public static <A extends Annotation> A findAnnotation(Class<?> clazz, Class<A> annotationType) {
        if (clazz == null)
            throw new IllegalArgumentException("Clazz parameter can't be null");

        A annotation = clazz.getAnnotation(annotationType);
        if (annotation != null)
            return annotation;

        for (Class<?> ifc : clazz.getInterfaces()) {
            annotation = findAnnotation(ifc, annotationType);
            if (annotation != null)
                return annotation;
        }

        if (!Annotation.class.isAssignableFrom(clazz))
            for (Annotation ann : clazz.getAnnotations()) {
                annotation = findAnnotation(ann.annotationType(), annotationType);
                if (annotation != null)
                    return annotation;
            }

        Class<?> superClass = clazz.getSuperclass();
        if (superClass == null || superClass == Object.class)
            return null;
        return findAnnotation(superClass, annotationType);
    }
}

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