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.authz.aop;
020    
021    import org.apache.shiro.aop.AnnotationMethodInterceptor;
022    import org.apache.shiro.aop.MethodInvocation;
023    import org.apache.shiro.authz.AuthorizationException;
024    
025    
026    /**
027     * An <tt>AnnotationMethodInterceptor</tt> that asserts the calling code is authorized to execute the method
028     * before allowing the invocation to continue by inspecting code annotations to perform an access control check.
029     *
030     * @author Les Hazlewood
031     * @since 0.1
032     */
033    public abstract class AuthorizingAnnotationMethodInterceptor extends AnnotationMethodInterceptor
034    {
035        
036        /**
037         * Constructor that ensures the internal <code>handler</code> is set which will be used to perform the
038         * authorization assertion checks when a supported annotation is encountered.
039         * @param handler the internal <code>handler</code> used to perform authorization assertion checks when a 
040         * supported annotation is encountered.
041         */
042        public AuthorizingAnnotationMethodInterceptor( AuthorizingAnnotationHandler handler ) {
043            super(handler);
044        }
045    
046        /**
047         * Ensures the <code>methodInvocation</code> is allowed to execute first before proceeding by calling the
048         * {@link #assertAuthorized(org.apache.shiro.aop.MethodInvocation) assertAuthorized} method first.
049         *
050         * @param methodInvocation the method invocation to check for authorization prior to allowing it to proceed/execute.
051         * @return the return value from the method invocation (the value of {@link org.apache.shiro.aop.MethodInvocation#proceed() MethodInvocation.proceed()}).
052         * @throws org.apache.shiro.authz.AuthorizationException if the <code>MethodInvocation</code> is not allowed to proceed.
053         * @throws Throwable if any other error occurs.
054         */
055        public Object invoke(MethodInvocation methodInvocation) throws Throwable {
056            assertAuthorized(methodInvocation);
057            return methodInvocation.proceed();
058        }
059    
060        /**
061         * Ensures the calling Subject is authorized to execute the specified <code>MethodInvocation</code>.
062         * <p/>
063         * As this is an AnnotationMethodInterceptor, this implementation merely delegates to the internal
064         * {@link AuthorizingAnnotationHandler AuthorizingAnnotationHandler} by first acquiring the annotation by
065         * calling {@link #getAnnotation(MethodInvocation) getAnnotation(methodInvocation)} and then calls
066         * {@link AuthorizingAnnotationHandler#assertAuthorized(java.lang.annotation.Annotation) handler.assertAuthorized(annotation)}.
067         *
068         * @param mi the <code>MethodInvocation</code> to check to see if it is allowed to proceed/execute.
069         * @throws AuthorizationException if the method invocation is not allowed to continue/execute.
070         */
071        public void assertAuthorized(MethodInvocation mi) throws AuthorizationException {
072            ((AuthorizingAnnotationHandler)getHandler()).assertAuthorized(getAnnotation(mi));
073        }
074    }