    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.collections4.functors;
    018
    019import java.lang.reflect.Constructor;
    020import java.lang.reflect.InvocationTargetException;
    021
    022import org.apache.commons.collections4.FunctorException;
    023import org.apache.commons.collections4.Transformer;
    024
    025/**
    026 * Transformer implementation that creates a new object instance by reflection.
    027 * <p>
    028 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore
    029 * in order to prevent potential remote code execution exploits. Please refer to
    030 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
    031 * for more details.
    032 * </p>
    033 *
    034 * @since 3.0
    035 */
    036public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {
    037
    038    /** Singleton instance that uses the no arg constructor */
    039    @SuppressWarnings("rawtypes")
    040    private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
    041
    042    /**
    043     * Gets a typed no-arg instance.
    044     *
    045     * @param <T>  the type of the objects to be created
    046     * @return Transformer&lt;Class&lt;? extends T&gt;, T&gt;
    047     */
    048    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() {
    049        return NO_ARG_INSTANCE;
    050    }
    051    /**
    052     * Transformer method that performs validation.
    053     *
    054     * @param <T>  the type of the objects to be created
    055     * @param paramTypes  the constructor parameter types
    056     * @param args  the constructor arguments
    057     * @return an instantiate transformer
    058     * @throws IllegalArgumentException if paramTypes does not match args
    059     */
    060    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes,
    061                                                                                final Object[] args) {
    062        if (paramTypes == null && args != null
    063            || paramTypes != null && args == null
    064            || paramTypes != null && args != null && paramTypes.length != args.length) {
    065            throw new IllegalArgumentException("Parameter types must match the arguments");
    066        }
    067
    068        if (paramTypes == null || paramTypes.length == 0) {
    069            return new InstantiateTransformer<>();
    070        }
    071        return new InstantiateTransformer<>(paramTypes, args);
    072    }
    073
    074    /** The constructor parameter types */
    075    private final Class<?>[] iParamTypes;
    076
    077    /** The constructor arguments */
    078    private final Object[] iArgs;
    079
    080    /**
    081     * Constructor for no arg instance.
    082     */
    083    private InstantiateTransformer() {
    084        iParamTypes = null;
    085        iArgs = null;
    086    }
    087
    088    /**
    089     * Constructor that performs no validation.
    090     * Use {@code instantiateTransformer} if you want that.
    091     * <p>
    092     * Note: from 4.0, the input parameters will be cloned
    093     *
    094     * @param paramTypes  the constructor parameter types
    095     * @param args  the constructor arguments
    096     */
    097    public InstantiateTransformer(final Class<?>[] paramTypes, final Object[] args) {
    098        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
    099        iArgs = args != null ? args.clone() : null;
    100    }
    101
    102    /**
    103     * Transforms the input Class object to a result by instantiation.
    104     *
    105     * @param input  the input object to transform
    106     * @return the transformed result
    107     */
    108    @Override
    109    public T transform(final Class<? extends T> input) {
    110        try {
    111            if (input == null) {
    112                throw new FunctorException(
    113                    "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
    114            }
    115            final Constructor<? extends T> con = input.getConstructor(iParamTypes);
    116            return con.newInstance(iArgs);
    117        } catch (final NoSuchMethodException ex) {
    118            throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
    119        } catch (final InstantiationException ex) {
    120            throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
    121        } catch (final IllegalAccessException ex) {
    122            throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
    123        } catch (final InvocationTargetException ex) {
    124            throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
    125        }
    126    }
    127
    128}