001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.shiro.aop;
020    
021    import java.lang.annotation.Annotation;
022    
023    /**
024     * MethodInterceptor that inspects a specific annotation on the method invocation before continuing
025     * its execution.
026     * </p>
027     * The annotation is acquired from the {@link MethodInvocation MethodInvocation} via a
028     * {@link AnnotationResolver AnnotationResolver} instance that may be configured.  Unless
029     * overridden, the default {@code AnnotationResolver} is a
030     *
031     * @since 0.9
032     */
033    public abstract class AnnotationMethodInterceptor extends MethodInterceptorSupport {
034    
035        private AnnotationHandler handler;
036    
037        /**
038         * The resolver to use to find annotations on intercepted methods.
039         *
040         * @since 1.1
041         */
042        private AnnotationResolver resolver;
043    
044        /**
045         * Constructs an <code>AnnotationMethodInterceptor</code> with the
046         * {@link AnnotationHandler AnnotationHandler} that will be used to process annotations of a
047         * corresponding type.
048         *
049         * @param handler the handler to delegate to for processing the annotation.
050         */
051        public AnnotationMethodInterceptor(AnnotationHandler handler) {
052            this(handler, new DefaultAnnotationResolver());
053        }
054    
055        /**
056         * Constructs an <code>AnnotationMethodInterceptor</code> with the
057         * {@link AnnotationHandler AnnotationHandler} that will be used to process annotations of a
058         * corresponding type, using the specified {@code AnnotationResolver} to acquire annotations
059         * at runtime.
060         *
061         * @param handler  the handler to use to process any discovered annotation
062         * @param resolver the resolver to use to locate/acquire the annotation
063         * @since 1.1
064         */
065        public AnnotationMethodInterceptor(AnnotationHandler handler, AnnotationResolver resolver) {
066            if (handler == null) {
067                throw new IllegalArgumentException("AnnotationHandler argument cannot be null.");
068            }
069            setHandler(handler);
070            setResolver(resolver != null ? resolver : new DefaultAnnotationResolver());
071        }
072    
073        /**
074         * Returns the {@code AnnotationHandler} used to perform authorization behavior based on
075         * an annotation discovered at runtime.
076         *
077         * @return the {@code AnnotationHandler} used to perform authorization behavior based on
078         *         an annotation discovered at runtime.
079         */
080        public AnnotationHandler getHandler() {
081            return handler;
082        }
083    
084        /**
085         * Sets the {@code AnnotationHandler} used to perform authorization behavior based on
086         * an annotation discovered at runtime.
087         *
088         * @param handler the {@code AnnotationHandler} used to perform authorization behavior based on
089         *                an annotation discovered at runtime.
090         */
091        public void setHandler(AnnotationHandler handler) {
092            this.handler = handler;
093        }
094    
095        /**
096         * Returns the {@code AnnotationResolver} to use to acquire annotations from intercepted
097         * methods at runtime.  The annotation is then used by the {@link #getHandler handler} to
098         * perform authorization logic.
099         *
100         * @return the {@code AnnotationResolver} to use to acquire annotations from intercepted
101         *         methods at runtime.
102         * @since 1.1
103         */
104        public AnnotationResolver getResolver() {
105            return resolver;
106        }
107    
108        /**
109         * Returns the {@code AnnotationResolver} to use to acquire annotations from intercepted
110         * methods at runtime.  The annotation is then used by the {@link #getHandler handler} to
111         * perform authorization logic.
112         *
113         * @param resolver the {@code AnnotationResolver} to use to acquire annotations from intercepted
114         *                 methods at runtime.
115         * @since 1.1
116         */
117        public void setResolver(AnnotationResolver resolver) {
118            this.resolver = resolver;
119        }
120    
121        /**
122         * Returns <code>true</code> if this interceptor supports, that is, should inspect, the specified
123         * <code>MethodInvocation</code>, <code>false</code> otherwise.
124         * <p/>
125         * The default implementation simply does the following:
126         * <p/>
127         * <code>return {@link #getAnnotation(MethodInvocation) getAnnotation(mi)} != null</code>
128         *
129         * @param mi the <code>MethodInvocation</code> for the method being invoked.
130         * @return <code>true</code> if this interceptor supports, that is, should inspect, the specified
131         *         <code>MethodInvocation</code>, <code>false</code> otherwise.
132         */
133        public boolean supports(MethodInvocation mi) {
134            return getAnnotation(mi) != null;
135        }
136    
137        /**
138         * Returns the Annotation that this interceptor will process for the specified method invocation.
139         * <p/>
140         * The default implementation acquires the annotation using an annotation
141         * {@link #getResolver resolver} using the internal annotation {@link #getHandler handler}'s
142         * {@link org.apache.shiro.aop.AnnotationHandler#getAnnotationClass() annotationClass}.
143         *
144         * @param mi the MethodInvocation wrapping the Method from which the Annotation will be acquired.
145         * @return the Annotation that this interceptor will process for the specified method invocation.
146         */
147        protected Annotation getAnnotation(MethodInvocation mi) {
148            return getResolver().getAnnotation(mi, getHandler().getAnnotationClass());
149        }
150    }