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

License

Declaration

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

Method Source Code

//package com.java2s;
/*/*ww w  . ja  v  a2s. c  o m*/
*  Copyright Beijing 58 Information Technology Co.,Ltd.
*
*  Licensed to the Apache Software Foundation (ASF) under one
*  or more contributor license agreements.  See the NOTICE file
*  distributed with this work for additional information
*  regarding copyright ownership.  The ASF licenses this file
*  to you 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.
*/

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import com.google.common.base.Preconditions;

public class Main {

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

        Preconditions.checkNotNull(clazz, "Class must not 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);
    }

    public static <A extends Annotation> A findAnnotation(Method method, Class<A> annotationType) {

        return method.getAnnotation(annotationType);
    }
}

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