src/org/jsecurity/aop/AnnotationMethodInterceptor.java

/*
 * Copyright 2005-2008 Les Hazlewood
 *
 * 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.jsecurity.aop;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;

/**
 * MethodInterceptor that inspects a specific annotation on the method invocation before continuing
 * its execution.
 * 
 * @since 0.9
 * @author Les Hazlewood
 */
public abstract class AnnotationMethodInterceptor extends MethodInterceptorSupport {

    protected Class<? extends Annotation> annotationClass;

    public void init() {
        super.init();
        if (annotationClass == null) {
            String msg = "annotationClass property must be set";
            throw new IllegalStateException(msg);
        }
    }

    public void setAnnotationClass(Class<? extends Annotation> annotationClass) {
        this.annotationClass = annotationClass;
    }

    public Class<? extends Annotation> getAnnotationClass() {
        return this.annotationClass;
    }

    public boolean supports(MethodInvocation mi) {
        return getAnnotation( mi ) != null;
    }

    protected Annotation getAnnotation(MethodInvocation mi) {
        if (mi == null) {
            throw new IllegalArgumentException("method argument cannot be null");
        }
        Method m = mi.getMethod();
        if (m == null) {
            String msg = MethodInvocation.class.getName() + " parameter incorrectly " +
                    "constructed.  getMethod() returned null";
            throw new IllegalArgumentException(msg);

        }
        return m.getAnnotation(getAnnotationClass());

    }

}