core/src/main/java/org/apache/ki/aop/AnnotationHandler.java

/*
 * 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.
 */
package org.apache.ki.aop;

import java.lang.annotation.Annotation;

import org.apache.ki.SecurityUtils;
import org.apache.ki.subject.Subject;


/**
 * Base support class for implementations that reads and processes JSR-175 annotations.
 *
 * @author Les Hazlewood
 * @since 0.9.0
 */
public abstract class AnnotationHandler {

    /**
     * The type of annotation this handler will process.
     */
    protected Class<? extends Annotation> annotationClass;

    /**
     * Constructs an <code>AnnotationHandler</code> who processes annotations of the
     * specified type.  Immediately calls {@link #setAnnotationClass(Class)}.
     *
     * @param annotationClass the type of annotation this handler will process.
     */
    public AnnotationHandler(Class<? extends Annotation> annotationClass) {
        setAnnotationClass(annotationClass);
    }

    /**
     * Returns the {@link org.apache.ki.subject.Subject Subject} associated with the currently-executing code.
     * <p/>
     * This default implementation merely calls <code>{@link org.apache.ki.SecurityUtils#getSubject SecurityUtils.getSubject()}</code>.
     *
     * @return the {@link org.apache.ki.subject.Subject Subject} associated with the currently-executing code.
     */
    protected Subject getSubject() {
        return SecurityUtils.getSubject();
    }

    /**
     * Sets the type of annotation this handler will inspect and process.
     *
     * @param annotationClass the type of annotation this handler will process.
     * @throws IllegalArgumentException if the argument is <code>null</code>.
     */
    protected void setAnnotationClass(Class<? extends Annotation> annotationClass)
            throws IllegalArgumentException {
        if (annotationClass == null) {
            String msg = "annotationClass argument cannot be null";
            throw new IllegalArgumentException(msg);
        }
        this.annotationClass = annotationClass;
    }

    /**
     * Returns the type of annotation this handler inspects and processes.
     *
     * @return the type of annotation this handler inspects and processes.
     */
    public Class<? extends Annotation> getAnnotationClass() {
        return this.annotationClass;
    }

}