    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.beanutils;
    018
    019import java.beans.IntrospectionException;
    020import java.util.Collection;
    021import java.util.Collections;
    022import java.util.HashSet;
    023import java.util.Set;
    024
    025/**
    026 * <p>
    027 * A specialized {@code BeanIntrospector} implementation which suppresses some properties.
    028 * </p>
    029 * <p>
    030 * An instance of this class is passed a set with the names of the properties it should
    031 * process. During introspection of a bean class it removes all these properties from the
    032 * {@link IntrospectionContext}. So effectively, properties added by a different
    033 * {@code BeanIntrospector} are removed again.
    034 * </p>
    035 *
    036 * @version $Id$
    037 * @since 1.9.2
    038 */
    039public class SuppressPropertiesBeanIntrospector implements BeanIntrospector {
    040    /**
    041     * A specialized instance which is configured to suppress the special {@code class}
    042     * properties of Java beans. Unintended access to the property {@code class} (which is
    043     * common to all Java objects) can be a security risk because it also allows access to
    044     * the class loader. Adding this instance as {@code BeanIntrospector} to an instance
    045     * of {@code PropertyUtilsBean} suppresses the {@code class} property; it can then no
    046     * longer be accessed.
    047     */
    048    public static final SuppressPropertiesBeanIntrospector SUPPRESS_CLASS =
    049            new SuppressPropertiesBeanIntrospector(Collections.singleton("class"));
    050
    051    /** A set with the names of the properties to be suppressed. */
    052    private final Set<String> propertyNames;
    053
    054    /**
    055     * Creates a new instance of {@code SuppressPropertiesBeanIntrospector} and sets the
    056     * names of the properties to be suppressed.
    057     *
    058     * @param propertiesToSuppress the names of the properties to be suppressed (must not
    059     * be <b>null</b>)
    060     * @throws IllegalArgumentException if the collection with property names is
    061     * <b>null</b>
    062     */
    063    public SuppressPropertiesBeanIntrospector(final Collection<String> propertiesToSuppress) {
    064        if (propertiesToSuppress == null) {
    065            throw new IllegalArgumentException("Property names must not be null!");
    066        }
    067
    068        propertyNames = Collections.unmodifiableSet(new HashSet<String>(
    069                propertiesToSuppress));
    070    }
    071
    072    /**
    073     * Returns a (unmodifiable) set with the names of the properties which are suppressed
    074     * by this {@code BeanIntrospector}.
    075     *
    076     * @return a set with the names of the suppressed properties
    077     */
    078    public Set<String> getSuppressedProperties() {
    079        return propertyNames;
    080    }
    081
    082    /**
    083     * {@inheritDoc} This implementation removes all properties from the given context it
    084     * is configured for.
    085     */
    086    public void introspect(final IntrospectionContext icontext) throws IntrospectionException {
    087        for (final String property : getSuppressedProperties()) {
    088            icontext.removePropertyDescriptor(property);
    089        }
    090    }
    091}